AVBS4004 | Food Safety Assessment & Management
8th August 2019
- Disease status, microbes, drugs and contaminants in the animal and their
environment can pose risks to the consumers
Introduction to food safety
Safe food production
- Involves the whole food chain → food safety can be compromised at any
stage on the ‘gate to plate’ continuum
Importance of food safety
- Includes on-farm and off-farm, pre-harvest, harvest and post-harvest
- Protecting consumers against food-borne illness
- Concerns the animal, the farm, the product, handling, processing and storage
- The avoidance of food-borne pathogens, chemical toxicants and physical
hazards via:
Modern food safety challenges
- Nutrition
- High demand due to ↑ population and wealth
- Food quality
- Labelling
- Trade and industries → global food safety standards (developing versus
developed)
- Education
- Climate change
Quality → Standards, nutritional or other attributes and appropriate labelling.
- Intensification of farming
Security → Enough food of appropriate quality.
- Consumers → lifestyle & eating habits, population dynamics and travel
Safe food → Reduce the chance of hazards entering the food chain - Prevention
of hazards reaching harmful levels.
When food safety is compromised…
- Has serious consequences
Five keys to safer food (WHO):
- Can cause mass morbidity and sometimes mortality
1. Cleanliness
- The media plays a large role
2. Separation of raw and cooked
- It is important that the stage where the breakdown occurred is correctly
identified in order to protect the industry
3. Cook thoroughly
4. Store at a safe temperature
Food borne disease
5. Safe raw sources
- Mostly sporadic and often not reported → reported cases of food-borne
disease are merely the ‘tip of the iceberg’
Why we need safe food
- Survival, growth, productivity, health and happiness
- Ingestion of hazardous substance: microbial (biological), chemical or physical
- Food of animal origins → inedible to edible proteins; total complement of
essential proteins
- More severe in developing world → poor food safety; less developed
farming practices and resources; inadequate cleaning and sanitation; poverty
- Healthy and happy animals = good quality and safe food = happy, healthy
consumers
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AVBS4004 | Food Safety Assessment & Management
and poor governance selling of diseased animals; use of dangerous
additives/chemicals; lack of refrigeration
Salmonella cases linked to recalled Honey Smack (USA, March 2018)
- 1.8 million people die from diarrhoeal illness → majority associated with
- Product recall completed in June
- 135 cases, 24 hospitalisations, in 36 states
contaminated food or drinking water
- Unopened cereal +ve for Salmonella
McDonald’s salads tainted with faeces (May 2018)
- 511 people in 16 states
- Cyclospora (protozoan) infection
- Source tainted lettuce blend → not cleaned properly OR contaminated by
workers
Food-borne illness on the rise?
- Even with progress and advancement in medicine, food science, food
technology, biosecurity & regulations and standards, food-borne illnesses are
still on the rise
- Enhanced and improved surveillance
- Improved diagnostics and food testing technology
Pathogen factors
- New and emerging food-borne pathogens → adaptation (e.g. acid tolerant
Notable cases
strains, antimicrobial resistant strains)
Salmonella Enteritidis in Shwan’s ice cream (U.S. 1994) → Estimated 224, 000
Environment factors
cases
- Changes in food production and processing → intensification,
globalisation, packaging
- Cross-contamination → ice-cream tanker that carried unpasteurised liquid
eggs containing S. Enteritidis
- ‘Time buffer’ between preparation and consumption
Hepatitis A in clams (Shanghai, 1988) → 300,000 cases, 11 deaths
Host factors
- Undercooked contaminated clams sourced from heavily polluted (sewage)
coastal waters
- Changes in food consumption patterns e.g. pre-packaged and microwave
foods
E. coli O104:H4 in sprouts (Europe, 2011) → 873 HUS cases, 45 deaths
- Changes in consumer requirements → convenience foods, low fat, salt, sugar
and preservative
- 13 European countries and U.S. and Canada
- Contaminated sprout farm employees that worked with a contaminated
imported fenugreek seeds
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AVBS4004 | Food Safety Assessment & Management
- Increase in ‘at risk’ population → ageing population = more people with
compromised health, poor knowledge, understanding and compliance of
safe food preparation and hygiene
- 2.7 million visits to doctors → >500,000 antibiotics prescriptions = $1.2
billion (reality ~ $2.6 billion)
Costs of food-borne illness
- Lost productivity
- Health costs
- Industry costs
Socio-economic consequences
- Government costs
- Individual → families, medical costs, income loss, pain and suffering,
rehabilitation
Food-borne illness in Australia
- Employer → sick days, productivity
Why
Consequences for food industry
- Lack of effective food safety practices
- Product recall, factory closures, liability costs and victim claims, loss of market
share, effect on the brand reputation, increased scrutiny, costs of introducing
- Pre-harvest, harvest and post-harvest
- Animals and workers
procedures to avoid recurrence
Public health and government
- Handling and storage
- Disease surveillance
- Food preparation and hygiene
- Cooking
- Outbreak investigation
- Clean up costs
Who
- Public education
- Elderly → esp. in nursing homes and hospital
- Implementation and enforcement of food safety regulations and preventative
activities (i.e. HACCP implementation and validation)
- Children → schools
- Food hygiene regulatory system costs the Australian government $18.6
million to enforce
- Festive season and celebration
When
- Parties/BBQ/seafood → increased chance for cross-contamination, poor
hygiene and undercooking
- Small business costs $337 million in compliance
- State/Territory responsibility
Australian examples
- Food Regulation Standing Committee (FRSC)
- 1995 — Garibaldi Enterohaemorrhagic E. Coli → killed 1 child
- Implementation Sub-Committee (ISC)
- 1996 — Kraft Peanut Butter Salmonella → 500 ill
Costs for Australia
- 1997 — Wallis Lake oysters (NSW) Hepatitis A → 1 death (77 year old man)
and >1500 sick
- 12 million days off work
- 2007 — Pork rolls (NSW) Salmonella Typhimurium → 319 cases
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AVBS4004 | Food Safety Assessment & Management
- Sites to implement control measures to prevent, reduce to an acceptable
level or eliminate hazards in food
- 2005-2010 — Raw eggs Salmonella Typhimurium → 100’s ill
- 2013 — Soft cheeses Listeria monocytogenes → 3 deaths, 2 miscarriages, 20+
cases
Quality assurance
- 2015 — Frozen Berries Hepatitis A → 18 cases
- Application and verification of control measures
Prevention
- “Insuring” safe food production through compliance with regulatory or
customer requirement
- NSW Food Authority → educational awareness campaign
- Quality is planned and obtained by implementing Standard Operating
Procedures (SOPs) at various steps along the food chain
- “Whole of food chain” → inspectorial and end-product approaches to hazard
control
- HACCP-based system
- Hazard identification and control through the application of science-based
- Good Hygiene Practices (GHPs)
structured activities throughout the food chain — i.e. recognise events or
practices at critical points in the food chain; influence the chance of hazards
- Good Management Practices (GMPs)
entry and/or proliferation in food
- Quality control = testing
- Establish critical food safety limits → temperature, time, moisture level, pH
and salt
‘Gate to plate’ philosophy
- Safe microbiological contamination levels
There are many risks throughout the food chain. These are managed using the
‘gate to plate’ wholistic approach.
Risk → Probability of an adverse health effect and the severity of that effect,
consequential to a hazard(s) being present in a food
Risk assessment → science of risk analysis: identify of the hazard, characterise
the hazard, knowledge of the consequences, likelihood of exposure,
characterises the risk → Feed into HACCP (establish critical limits, monitor and
implement scientific based control measures at CCPs, prevent, reduce to an
acceptable level or eliminate a hazard
Hazard Analysis Critical Control Point (HACCP)
- Powerful risk management tool
- Structured preventative system
- Safety through identification of hazards, assessment and control measures
Critical Control Point (CCP)
- Monitor of hazard entry and levels at various key points in the food chain
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AVBS4004 | Food Safety Assessment & Management
- Application of standards and appropriate preventative measures throughout
the chain
Principles of food safety
- Greatest hazard control
- Greatest quality assurance
Categories of food-borne hazards
- Greatest confidence
Biological
- Easy to identify violation and correct
Bacteria
- Holistic approach to food safety
- Replicate in food
- Evaluates all elements of the food chain › Interaction, communication and
standardisation within and between elements of the food chain
- Most important food hazards
- Salmonella spp. → meats (esp. poultry) and eggs
- Reducing the risk of food-borne disease
- Campylobacter jejuni → eats (esp. poultry)
- Enhances the effectiveness of food safety systems
- Escherichia coli → meats
- Provides consumers with the highest assurance of safe food production
- Vibrio spp. → seafood
- Industry and government confidence and assurance of safe food production
- Listeria monocytogenes → Dairy
→ good for business and public health
- Staphylococcus aureus → Dairy
Scientists’ role
- Clostridium spp. → Dairy, meats, eggs and honey
- Surveillance and monitoring
Viruses
- Investigating outbreaks
- Can’t replicate in food
- Laboratory testing
- Contaminate food, usually from human origin (faeces, vomit)
- Food safety research
- Human origin → Norovirus, Rotavirus, Hepatitis A and E
- Advising decision makers and policy development
- Seafood origin
- Developing recommendation and strategies for industries and governments
Parasites
- Communication and education
- CANNOT replicate in food
- Humans are often intermediate host
- Metazoan parasites (worms)
- Multicellular
- Cestodes (tapeworms)
- Nematodes (roundworms) — e.g. Trichinella spiralis
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AVBS4004 | Food Safety Assessment & Management
- Trematodes (flukes)
- Hormones and Hormone-like growth promoters
- Protista (Protozoa)
- Food additives (perceived as high risk)
- Organised and complex single cells
- Dyes
- Water and faecal material
- Flavour enhancers
- Flagellates — e.g. Giardia spp.
- Nitrites and nitrates
- Coccidians — e.g. Cryptosporidium parvum, Toxoplasmsa gondii,
Cyclospora cayetanesis
- Polyphosphate
- Smoke
Chemical
- Packaging compounds
- Allergens → e.g. Peanuts, shellfish, gluten, antimicrobials
- Industrial pollutants
- Natural toxins
- Heavy metals (lead, mercury (in fish), arsenic)
- Mycotoxins — e.g. aflatoxins = cirrhosis of the liver
- Halogenated hydrocarbons (polychlorinated biphenyls (PCBs), and dioxins
(chlorinated wastes) are carcinogenic and teratogenic
- Algal toxins — marine phycotoxins
- Plant toxins — pyrrolizidine alkaloids in honey = liver damage
- Agricultural chemicals
- Insecticides
- Shellfish toxins — cyanobacteria and algal marine phycotoxins
- Herbicides
- Scombroid — histamine in fish
- Fungicides
- Chemical hazards can accumulate in animal tissue over time → continues
small levels over a life time in animal
- Fertiliser
Physical
- Rodenticides
- Detergents and disinfectants
- Antibiotics
- Any potentially harmful extraneous matter not normally found in food → e.g.
glass, wood, stones, metal, plastic, bandages, human hair, bone fragments,
feathers, insects
- Anti-parasitics
Prevention
- Tranquilisers
- Separate and controlling physical hazards
- Anaesthetics
- Filter or sieve (ground meat)
- Anti-inflammatory drugs
- Metal detector (all foods)
- Vaccines and immuno-enhancers
- Good employee practices (jewellery)
- Veterinary medicines
- Good sanitation and quality control programs (hygiene)
- Medicated premixes
- Antimicrobial growth promoters
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AVBS4004 | Food Safety Assessment & Management
Dynamics and risk
Risk
Risk → Likelihood and consequence
- Food → consequences vary
- Infectious dose
- Likelihood of consequential event
- Effects — illness and severity
- Wider ramification e.g. release of exotic pathogens
E. coli O157:H7 (high risk)
- Low infectious dose ~10 CFU
- Severe gastroenteritis → bloody diarrhoea → systemic consequences →
Hemolytic uremic syndrome (HUS) → need for medical attention
- Integral in HACCP design → risk management and risk communication
- Specific to given hazards or cover a range of hazards, e.g. pasteurisation
design
Bacillus cereus (low risk)
- High number to cause illness → >1 million colony forming units (CFU)
needed to produce enough toxins
- Goal → food chain management and control of hazards using science,
practices and informing
- Illness is mild and short lasting (<24 hours)
- Food activities that reduce risk of food-borne disease - Consumer confidence
and well-being to acceptable levels
- Few need medical assistance, with few having any complications
Risk analysis
Host-Hazard-Environment interaction
- Food is a vehicle for hazards
- Nature of food → pH, water, composition
- Food environment → on-farm (animal) and off-farm (food product) influence
hazard types & levels, and the dynamics & risk of disease
- Animal husbandry will influence disease risks → management of disease
- Food processing will influence disease risks → handling of animals at
slaughter; harvesting conditions; temperature and handling of foods;
cooking and preparing of foods
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AVBS4004 | Food Safety Assessment & Management
Introduction to food
microbiology
The role of epidemiology in food safety
The study of microbes (bacteria, viruses, parasites, yeasts, moulds, toxins they
produce) and their interaction in food.
Categories of food microbes
Desirable organisms
- Change food property and alter preservation
- Identify hazards in food poisoning outbreaks
- Bacteria, yeast or moulds — e.g. Lactobacillus and Bifidobacterium → ‘Starter
cultures’
- Trace back to the source
- Fermented foods
- Provide information on factors associated with diseases outbreak
- Used for:
- Identify food safety faults
- Acid and alcohol production
- HACCP, standards, regulations and policy
- Production of bacteriocins
- Feedback on food safety efficacy
- Removal of toxic components
- Disease surveillance
- Improved digestibility
- Monitoring hazards
- Retention of micronutrients
- Monitoring population dynamics and host activity
- Flavour enhancers
- “At risk” activities and groups
Spoilage organisms
- Well-being and economic affects
Spoilage → damage that causes the food to become unpalatable to the
- Implement proactive corrections
consumer; “off-smelling or tasting”.
- Recommendations to decision makers
- Proteolysis and putrefaction → spoiled foods often harbour pathogens due to
protein breakdown
- Unsafe food will not always smell or taste spoiled
- Spoilage organisms usually aren’t harmful, but allow for harmful organisms to
proliferate
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AVBS4004 | Food Safety Assessment & Management
How they cause disease
- Moulds and yeasts
- Souring bacteria
Food source → Gut survival and/or attachment → Compete and evade →
Indicator organisms
Replicate and/or invade → Damage, spread and symptoms
Invasive organsims
- Non-pathogens associated with pathogens
- Attach and penetrate tissue
- Used an indicator of faecal contamination or unhygienic conditions
- Replicate (some intracellularly)
- Easier and cheaper to test
- Local and systemic affects → inflammation, cellular invasion, tissue
destruction
- An ideal indicator will behave in a similar way to pathogens
- E.g. → Coliforms indicate for Gram –ve’s, Enterobacteriaceae, Lactose
fermenters and E. coli (faecal coliform)
- Intracellular pathogens: Enteroinvasive Escherichia coli (EIEC), Salmonella
spp. and Listeria monocytogenes
- Important for food safety, quality and sanitation as it detects:
Non-invasive organsims
- Excessive contamination of raw food
- Attach to gut tissue using adhesins or fimbriae/pili (F antigens)
- Failure of food preservation and protection
- Colonises or replicates in the gut with NO invasion
- Alternatives?
- Leads to malabsorption, diarrhoea and local inflammation
- Total aerobic counts (general contamination)
- E.g. Giardia lamblia uses adhesion cups
- Spore counts (environmental contamination) → e.g. Bacillus spp. or
Clostridium spp.
Toxico-infectious
Pathogenic organisms
- Ingestion of microbe → replication (can be invasive or nononvasive) →
production of toxins (e.g. EHEC, ETEC, Vibrio cholerae)
Pathogen → a microbe that can cause disease in the host -
- Toxico-infectious botulism
Infection → growth and/or invasion within a host
Intoxication from preformed toxins
Poisonings → toxin productions
- Just need to ingest the toxin in food → no microbial ingestion
- Food is the vehicle: entry at various points
- Kill the microbe but the toxin is still viable
- Critical Control Points CCPs
- E.g. → Staphylococcal food poisoning from heat-stable enterotoxins
- Ingestion of contaminated food
- E.g. → Shellfish toxins — Phytoplankton toxins (algal blooms)
- Food Safety: Prevent, eliminate or reduce to acceptable levels (negligible
risk)
Survival and replication in food
Intrinsic factors (nature of the food)
Food-borne pathogens
Acidity / pH
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AVBS4004 | Food Safety Assessment & Management
- Growth from pH 4-8
- Psychrotrophs → grow in the fridge e.g. Listeria monocytogenes (<5ºC)
- Growth decreases when too acidic (low pH) or caustic (high pH)
- Mesophils → optimum growth ~37 ºC e.g. large range of bacteria, moulds
and yeasts
- Large pH changes disrupt microbial cell membranes and enzyme activity
- Thermophils → grow > 45ºC e.g. resistant spore formers (Bacillus spp. and
Clostridium spp.)
- Organic acids used in preservation → e.g. propionic acid for cheese
- Organisms used to alter pH → e.g. lactobacillus in fermented foods
- Temperature ‘Danger zone’ → 5-60 ºC
Oxidative-reductive potential
- More time in the danger zone → More proliferation → More toxins → More
- +Eh → oxidising i.e. aerobic microbes (including yeast and moulds)
risk
- —Eh → reducing i.e. anaerobic microbes (e.g. Clostridium)
Relative humidity
Biological and physical structure
- Relation to aw
- Ground beef and cracked eggs are high risk
- High relative humidity → rapid microbial growth
Nutrient composition
- Dry foods stored in moist environments → surface slime and mould
- Most animal based foods products are full of essential nutrients
- Higher the storage temperature → lower relative humidity
- Bacterial growth ✓ → Raw animal derived foods are classified as hazardous
- Warmth and moisture = bacterial proliferation
Antimicrobial composition
Improper wrapping of refrigerated foods
- Natural substances in cows milk and eggs
- High humidity of the fridge
- Lysosyme and lactoferrin → Can be used on carcasses as microbial blockers
- Aerobic atmosphere due to poor wrapping
- Prudent antibiotics usage in animals needed → reduce antimicrobial
resistance development in food-borne pathogens
- No gaseous atmospheric control = bacterial proliferation
Modified atmospheric packaging (MAP)
Water activity (aw)
- Prolonged shelf-life
- Measure of ‘available water’
- Gas flushing with high CO2 → Inhibit Gram negative bacteria, prolong meat
preservation — esp. raw meat, processed and fermented meats (salami and
- Ratio relating vapours of food to vapour of distilled water
- Closer the aw is to 1 the more moist the food
cured hams)
- Needs to be > 0.6 for microbial growth
Biocontrols
- Lowering aw with salt/sugar/drying reduces microbial growth
- ‘Starter cultures’
Extrinsic factors (environment)
- Control fermentation in foods e.g. cheese, salami
Temperature
Food preservation, protection and hygiene
- Microbes of interest in food microbiology grow in the range of 8 – 42ºC
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AVBS4004 | Food Safety Assessment & Management
Dehydration
- Stops microbial growth and enzymatic activity
- Post slaughter meat temperature
- Prevents rotting meat
- Cold chain in milk production important
- Longer shelf-life
- Benefit from refrigeration (large meat sizes)
Fermentation
- Inhibits germination and growth of microbes
- Gradual chemical change caused by the enzymes and acidic microbial byproducts → ‘Starter cultures’
- Modern facilities → fans and heaters in controlled environments
- E.g. beef jerky
- Cheeses using lactic acid producing bacteria have long-shelf lives
- Adding sugar and salt has the same affect
- Pickling foods with vinegar or other acids works in a similar fashion — i.e. pH
lowering
Heating
Chemical preservatives
- Important to consider temperature and time
- Destroys pathogens and spoilage microbes
- Allowable additives (FSANZ Standard 1.3.1)
- D value = decimal reduction time
- “Natural” chemicals
- Thermal Death Time (TDT)
- Acetic acid carcasse washing
- Control activities
- Smoking
- Phenols (anti-microbial)
- Pasteurisation → High temperature-short time (HTST)
- Heating at 72ºC for 15 seconds (Flash method)
Irradiation
- Milk passes through heated plates or tubes
- Destroys pathogens and spoilage organisms
- Wide safety margin for many other milk pathogens (Listeria, E. coli,
Campylobacter, Salmonella, Brucella)
- Not used for animal derived foods in Australia
- 40 countries worldwide & NASA
- Effective against coccidians (oocytes) and Giardia
- Gamma ray emission: 60Co or 137Cs
- Canned food sterilisation
- Some microbes are resistant
What can survive pasteurisation?
- Degrees of sterilisation similar to heat
- Spore-formers → e.g. Clostridium spp., Bacillus spp.
Food hygiene and sanitation
- Thermophilic Gram +ve bacteria
- Toxins
- Minimise the chance of build up and transferring contaminates and
pathogens from a source (food or human) to a food through proper cleaning
and sanitation of equipment used in food processing and preparation
Freezing/refrigeration
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AVBS4004 | Food Safety Assessment & Management
- Wash cutting boards, knives, utensils and counter tops in hot soapy water or
run through the dishwasher after each food item
- Direct or indirect contact
- Direct cross-contamination
- Plastic or other non-porous cutting boards
- Involves the transfer of a harmful agent from a contaminated food to a non
- Use disposable paper towels
contaminated food by direct physical contact or by contact with liquids
without the aid of a vehicle.
- Reduce microbe accumulation
- Reduce the chance of cross-contamination
- Raw foods mix with cooked or ready-to-eat foods
Basic steps:
- Blood from thawing meat dropping onto fresh vegetables stored on a shelf
below
- Clean – free of visible soil
- Indirect cross-contamination
- Sanitise – reduce the number of microbes to a safe level using heat or
chemical
- Involves the transfer of a harmful agent from a contaminated food to a non
contaminated food by a vehicle, such as a hands, utensils or other
- Sterilise – to make free of microbes
equipment
- “Commercial sterilise” → no viable organisms can be detected
- Raw meats prepared with a knife and cutting board which are not cleaned
- Canned solid foods can’t go above ~140ºC without degrading the food
quality
after use → most common type of cross contamination
Prevention of cross-contamination
Personal hygiene
- Keep raw meat, poultry and seafood separate from each other and other food
- Key to reducing microbial disease risk
- Store raw meat, poultry and seafood on the bottom of the refrigerator
- Reducing the chance of transferring pathogens and contaminates from one
source to another
- Use one cutting board for raw meats and another for salads and other ready
- Personal hygiene and sanitation practices throughout the food chain
- Wash cutting boards and utensils with hot soapy water after contact with raw
meat products
to eat food
Handwashing
- NEVER place cooked food on a plate that previously held raw meats
- Reduces faecal-oral transmission
Cooking and storage of food
- Single use gloves
- Washing between glove change
- Inadequate cooking and/or cooling of food
- FSANZ standard 3.2.2
- Incorrect storage temperature
- Personal hygiene requirement → business can be liable if they fail to
enforce this code
- Temperature abuse
- Long time lapses between stages of food preparation (in kitchen, delivery of
foods, uneven refrigerated trucks and tankers, shops to fridge/freezer)
Cross contamination
- On-farm
- Transfer of a harmful substance from one food to another
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AVBS4004 | Food Safety Assessment & Management
- Opportunities to survive and/or proliferate
- Influencing risk
- Cooking won’t kill everything
- Heat-stable toxins → e.g. Staphylococcal toxins and heat resistant spores
15th August 2019
Food safety regulation
Introduction
Global food safety trends
The NSW Food Authority
- A safe food supply is one of life’s fundamental necessities, essential for health
and well-being – and, in turn, economic growth and development.
- The NSW Food Authority is a through-chain food safety agency that works to
ensure food produced, manufactured and sold in NSW is monitored and safe
at each step — from paddock to plate
- The production and consumption of safe food are central to any society
- It has a wide range of economic, social and, in many cases, environmental
consequences
- Provides certainty in the safety and integrity of the food supply chain in NSW
by regulating and measuring food safety across the food industry
- Food production and distribution are globalised and even more complex
- The NSW Food Authority is a State Government agency, established in 2004,
to provide New South Wales with an integrated food regulation system
- The advent of emerging pathogens and the impacts of climate change on
food safety are adding to this complexity
- The Food Authority provides the regulatory framework for the food industry
in New South Wales by administering and enforcing State and national food
legislation
- An increasing population of at-risk (immunocompromised and ageing)
consumer
- Changing patterns of human consumption as fresh and minimally
processed foods are preferred
- The authority has a “mission” with 3 main goals:
- Safer food
- Increased affluence shifts food consumption patterns from basic staples
towards more appetising, nourishing and safe food
- Clearer choices
- Protect the community
Annual food-borne disease burden in Australia
- 5.4 million cases foodborne gastroenteritis → 18,000 hospitalisations → 120
deaths
- Costs over $2.6 billion per year
- 2.1 million days off work
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- 1.2 million doctor visits
What happens if SE is detected on a poultry farm or facility?
- 300,000 prescriptions
- If a poultry farm or facility has confirmed positive tests for SE it is quarantined
under an Individual Biosecurity Direction (IBD) that is issued by NSW DPI
- 42,000 chronic symptoms
- The IBD puts legal restrictions on the farm so that eggs, birds, other livestock,
equipment and litter are only able to be removed under a permit to a
licensed or approved facility
Case study: Salmonella Enteritidis (SE) and eggs
- SE is present in most international egg industries and is associated with
human illness and egg consumption
- Tracing of facilities or other businesses with recent contact with the affected
premises will be undertaken and samples from those properties will be
collected and investigated
- Until recently, SE had not been detected in NSW poultry
- Usually human illness linked to SE in NSW is associated with recent overseas
travel; people getting infected overseas before returning home
- A DPI liaison officer will be available for the affected premises to provide
advice and support
- Since May 2018, there has been an emergence of cases where people
- Affected poultry farms or facilities are required to undergo full
decontamination and undertake testing for SE before they can start operating
again
became infected from consuming food locally in NSW
- NSW government agencies have worked collaboratively to identify the
sources of these cases
Case study: 2x milk recalls in Victoria
- 13 NSW poultry egg facilities and one Victorian poultry egg facility have had
detections of SE
Milk recall relating to chemical contamination
- The first detection was in NSW in September 2018 more detections have
been occurring as a targeted program of increased testing and surveillance
continues across a number of properties
- On 13 June 2019 Lactalis Australia Pty Ltd initiated a food recall to remove a
number of Pauls and Coles branded milks from the marketplace, due to
chemical contamination
- All the properties confirmed to have had SE present are interconnected in that
people, eggs or equipment were moving between them
- The chemical is a food grade cleaning solution used for cleaning milk plant
equipment
- Steps taken to minimise consumer exposure to SE include movement
restrictions, decontamination and improvements to biosecurity, consumer
level and trade level recalls, product withdrawals, consumer advisories, media
and surveillance
- It poses a low public health risk and there have been no reports of illness
- Affected milk products may have a yellowish colouring and/or metallic
chemical taste
- Lactalis advised that all potentially contaminated product was recalled and
the source of the problem had been identified
How is NSW DPI responding?
- NSW DPI is working closely with local and interstate agencies, affected
producers and peak industry bodies as part of the ongoing investigation
Milk recall relating to E. coli contamination
- On 20 June 2019 Lactalis Australia Pty Ltd initiated a food recall to remove a
number of different branded milks from the marketplace
- NSW DPI has increased surveillance and monitoring at poultry facilities and,
where necessary, biosecurity directions have been issued to individual
properties, including the quarantine of premises to stop movement of eggs
into the marketplace
- E. coli contamination was detected during routine company testing
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- The source of the problem was identified as a processing failure
- Due to the botulism scare that rocked the New Zealand dairy industry, the
Fonterra Shareholders' Fund units fell to its lowest level in 2013. More than
$NZ60 million were lost from the fund's market value.
- Lactalis advised that all products manufactured at the site would only be
released following microbiological testing to confirm product safety
- There were no reports of illness
International food safety scares
- Globally, the media and consumers have developed a much greater interest
in food safety issues owing to the continuing incidence of food scares
- In Germany in 2011, a new strain of E. coli linked to bean sprouts infected
more than 3,500 people and killed 53
- In the U.S.A in 2011, a Listeria outbreak resulted in 100 cases and 18 deaths,
Global Food Safety Regulation
leading to recalls of about 5 000 freshly cut rockmelons
- In the U.S.A in 2008-2009, a Salmonella outbreak linked to peanut butter
resulted in more than 500 cases in 43 states and led to recalls worth US$1
billion
- Food safety strategies in recent decades are taking a value chain approach
and introducing traceability requirements
Top 10 Chinese food scandals
Global regulatory frameworks
1. Melamine Milk scandal (2008)
- 6 babies died and 294,000 were made sick from the intentional addition of
melamine to various foodstuffs, mainly milk and infant formulas
World Trade Organisation (WTO)
- Under two binding agreements:
2. Toxic Bean-sprouts (2011)
1. Sanitary and Phytosanitary Measures [SPS Agreement]
3. Pesticide-drenched ‘yard-long’ beans (2010)
2. Technical Barriers to Trade [TBT Agreement]
4. Leather milk (2011)
Codex Alimentarius Commission (CAC)
5. ‘Aluminium’ dumplings
6. Glow-in-the-dark pork
- Uses various instruments, for example, the Code of Practice for Fish and
Fishery Products and the basics texts on Food Hygiene
7. ‘Lean meat powder’ pork
FAO Code of Conduct for Responsible Fisheries
8. Toxic take-away boxes (2010)
- Especially under Article 6 General principles, provisions 6.7 and 6.14 and
Article 11 (Post-harvest practices and trade), both of which are of particular
relevance to fish trade, safety and quality
9. ‘Sewer’ oil
10.‘Cadmium’ rice
Hazard Analysis and Critical Control Points (HACCP)
Economic impact on food businesses
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AVBS4004 | Food Safety Assessment & Management
- Based on the concept that traceability is only useful in investigations → by the
time an outbreak happens its too late → need to ensure each step in the
production process is done correctly before its progresses to the next stage
- Now been adopted by international bodies and trading countries and
regions to control food safety
International Organisation for Standardisation (ISO)
- Recently, the International Organization for Standardization (ISO) has
developed the ISO 22000 family of standards on food safety management
systems.
- It takes the approach of ISO 9001 as a management system, and incorporates
the hygiene measures of prerequisite programmes and the HACCP principles
and criteria
- In 2008, PAS 220:2008 was developed to cover what were seen to be
shortcomings in the prerequisite element of ISO 22000 at the time
Regional regulatory frameworks
Europe
- European Food Safety Authority is the principal agency in EU
- Regional agencies take responsibility to implement the regulations
- UK: Food Standards Agency
USA
HACCP principles
- Multiple agencies, two major are:
1. Conduct and hazard analysis
- Food and Drug Administration
2. Determine the Critical Control Points (CCPs)
- USDA Food Safety and Inspection Services
3. Establish critical limits
Canada
4. Establish monitoring procedures
- Canadian Food Inspection Agency
5. Establish corrective action
China
6. Establish verification procedures
- Chinese Food and Drug Administration works in collaboration with several
regional agencies and Authorities
7. Establish record-keeping and documentation
Singapore
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AVBS4004 | Food Safety Assessment & Management
- Agri-Food Veterinary Authority, Singapore
3. Standing Committee of China’s National People’s Congress revised the 2009
Food Safety Law (FSL) (2015)
UAE
- Responsible for reforming the FSL imposing more stringent controls on
food safety risks and ensuring greater government accountability towards
- Abu Dhabi Food Control Authority
Australia
consumers
- Several regional agencies
New Zealand Food Act 2014
- NSW Food Authority
- Food Standards Australia New Zealand (FSANZ)
- The Food Act 2014 came into force on 1 March 2016. It takes a new approach
to managing food safety
New Zealand
- The stated purpose of the Act is to improve food safety in New Zealand
- NZ Food Safety Authority (MPI)
- In this Act, there is more emphasis on managing risk than proscribing specific
policies and practices
- Food Standards Australia New Zealand (FSANZ)
FSANZ’s Compendium of Microbiological Criteria for Food (2016)
Recent initiatives in food safety
Safe Food for Canadians Act
- Microbiological testing can play an important role in food safety
management
- Canada approved its comprehensive food safety legislation known as the
Safe Food for Canadians Act (SFCA) in 2012
- The compendium is a guiding document to provide the reason for testing
clearly and the test applied is appropriate
- The legislation was developed to streamline Canada’s food safety regulations,
improve regulatory oversight, and increase international regulatory alignment
with its key trading partners, particularly the United States
Australian Food Safety
Regulation
The FDA’s Food Safety Modernisation Act (FSMA)
- Approved in 2011
National regulation
- The most sweeping reform of the US food safety laws in more than 70 years,
was signed into law on January 4, 201
Australia and New Zealand Food regulatory model
Australian New Zealand Forum on Food Regulation (ANZHFR) → responsible for
developing domestic food regulation policy in the form of policy guidelines.
- It aims to ensure the food supply is safe by shifting the focus from responding
to contamination to preventing it
Chinese food safety regulatory reforms
Food Regulation Standing Committee (FRSC) → responsible for coordinating
policy advice to the Forum and ensuring a nationally consistent approach to the
implementation and enforcement of food standards.
1. Food Safety Law of the People’s Republic of China (FSL)
2. The China Food and Drug Administration (CFDA) (2013)
Department of Health and Ageing (DoHA) → CEO of DoHA chairs the FRSC
- Oversees food manufacture, distribution and consumption, and to manage
regulation processes for food and drug safety
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AVBS4004 | Food Safety Assessment & Management
Through chain regulation
Implementation Sub-Committee for Food Regulation (ISFR) → aims to ensure
food standards are implemented and enforced consistently. ISFR is made up
of representatives from food regulation authorities
- Primary production and processing standards
- “whole of chain”
- “outcome-based standards
Nationally developed policy and standards
- Food policy development is the responsibility of the Australia New Zealand
Forum on Food Regulation (FoFR) (formerly called the Food Regulation
Ministerial Council)
- Development of national food safety standards is the responsibility of Food
Standards Australia New Zealand (FSANZ)
Implemented at a state and local level
- Enforcement is the responsibility of the relevant State or Territory department
- through state Food Acts
The food regulatory system in Australia
- Consumer affairs → deals with the appropriate and correct labelling of foods
(for nutritional content and health claims)
- Need to compromise with industry so as to not burden them with excessive
regulation
National Food Safety Regulations
Food regulatory system
National food regulatory system
- How food standards are created
- NSW Food Authority’s role
- Powers under the Food Act
- Liaison with Health, Primary Industries and Local Government
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AVBS4004 | Food Safety Assessment & Management
Food Standards Australia New Zealand
- Cereals, meat, dairy, eggs, fish, fruit and vegetables, alcoholic beverages
etc.
- Established under the FSANZ Act 1991 as a statutory agency
- Chapter 3 – Food Safety Standards
- previously Australia New Zealand Food Authority (ANZFA)
- Food safety programs
- National Food Authority (NFA)
- Food safety practices and general requirements
- Main responsibility is to administer the Australia New Zealand Food
Standards Code based on scientific/technical criteria, consistent with policy
guidelines
- Premises and equipment
- Chapter 4 – Primary Production Standards
- Seafood, poultry meat, meat, dairy products, eggs and egg products, seed
sprouts
- Formally review amendments to the Food Standards Code and decide on the
adoption of those standards
- New food standards or variations must be approved by the FSANZ Board and
Standards relating specifically to food safety
Ministers
- Food safety is covered by several standards in the Australia New Zealand
Food Standards Code
- Ministers have a power to refer back to FSANZ any newly adopted
standard, for review
Food Standards Code
- These standards aim to lower the incidence of food-borne illness by
strengthening food safety and traceability throughout the food supply chain,
- Food standards have the force of law and it is a criminal offence in Australia to
supply food that does not comply with the relevant food standards
- The standards are:
from paddock to plate
- Food Safety Standards (Chapter 3 – Australia only)
- It is also an offence to sell food that is unsafe or adulterated (with
microbiological or chemical contamination) or unsuitable for human
consumption (damaged, deteriorated or perished)
- Primary Production and Processing Standards (Chapter 4 – Australia only)
- Microbiological Limits for Food (Standard 1.6.1)
Australia New Zealand Food Standards Code
Roles and responsibilities of food regulation
- Chapter 1 – General Food Standards
1. Set overarching food policy
- Part 1.2 – Labelling and other information requirements
2. Develop and administer the food standards code
- Part 1.3 – Substances added to foods (food additives, processing aids,
vitamins and minerals)
3. Enforce the code
- Part 1.4 - Contaminants and Residues (natural toxicants, MRLs)
- Part 1.6 – Microbiological and Processing Requirements
- Chapter 2 – Food Product Standards
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AVBS4004 | Food Safety Assessment & Management
NSW Food Act (2003)
NSW food regulation
- Designates the NSW Food Authority as the enforcement agency responsible
for enforcing food standards in NSW
- Gives power to the regulations for the handling of food for sale and the sale
of food and to provide for the application of the Australia New Zealand
Food Standards Code in New South Wales; to repeal the Food Act 1989
- Ensures food for sale is safe and suitable for human consumption – prevents
misleading conduct in connection with the sale of food
- Provides power of entry to authorised officer to conduct inspections, seize
food, serve prohibition notices and issue Penalty Infringement Notices
(PINs)
NSW Food Authority
- Single agency responsible for enforcement of all food safety requirements
and labelling (for retail and primary production)
- Prior to the formation of the Authority, food regulation was divided among
various departments including:
- NSW Health
- NSW Dairy Corporation
- NSW Meat Industry Authority
- NSW Fisheries
Role of the NSW Food Authority
1. Conduct inspections of some retail premises
2. Investigate cases of food-borne illness
3. Investigate food-related complaints
4. Consumer and industry help line 1300 552 406
5. Surveys (e.g. kebabs, bakery, sushi, fresh noodles)
6. Input into National policy, work with Local councils
- The Food Standards Code is given legal effect by the laws of NSW, namely the
Food Act 2003 and the Food Regulation 2015
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AVBS4004 | Food Safety Assessment & Management
The NSW Food Authority’s approach
- The NSW Food Authority oversees areas involved in the processing and
manufacture of products
1. Risk assessment
2. Risk management
- Abattoirs, boning rooms, butcher shops
3. Risk communication
- Milk and dairy products
Risk analysis → is a process consisting of three components: risk assessment,
risk management, and risk communication. In relation to food safety, “risk”
means the probability of exposure to a hazard having a meaningful impact on
public health.
- Seed sprouts, pre-packed cut vegetables/fruit, unpasteurised juice
- Egg processing
- Secondary manufacture → Food Act and Food Standards Code
Australian Meat Hygiene Standards
Food safety ‘risk-based’ vs ‘hazards-based’ approach → Over last 20 years there
has been a gradual shift from a “hazards-based approach” to food safety (i.e.,
the mere presence of a hazard in a food was deemed unsafe) to a “risk-based
- AS4696:2007 Australian Standard for the Hygienic Production and
Transportation of Meat and Meat Products for human consumption
- AS4465:2005 Australian Standard for Construction of Premises and Hygienic
approach” (determination whether the exposure to a hazard has a meaningful
impact on public health).
Production of Poultry Meat for
Human Consumption
Risk assessment approach
- AS4464:2007 Australian
1. Botulism is a real risk (C. botulinum is anaerobic and is often found on the
surfaces of fruits and vegetables)
Standard for the Hygienic
Production of Wild Game
Meat for Human
Consumption
2. Severe outcomes rare (not in Australia) but have a high mortality rate (5–
10%)
3. Vegetables in oil remain a niche product (number of commercial
manufacturers of these products remains small)
Priority Classification System
- Classifies businesses/
industry according to level
of food safety risk
4. Regulations still applicable to manage risk (Standard 2.3.1 of the Code - this
class of product must not have a pH greater than 4.6. C. botulinum will not
grow at a pH<4.6)
- This makes priority setting
for regulation development
- Risk assessments need to be undertaken on a continuous basis
much easier
- Risk assessments provide a structured and transparent approach for
organising and evaluating data and information and a means of measuring
the uncertainty associated with the findings
- Hazards are dynamic in nature and their potential adverse effects on health
may change i.e. food habits and food composition
Examples of the NSW Food Authority’s actions
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22 August 2019
Disease and food safety:
ruminants
Ruminants
- ‘Cud chewing’ mammals = Ruminate
- Indigestible plant matter → digestible energy sources
- Microbial fermentation in the rumen
- Fermentation of ingested plant carbohydrates (cellulose and starch etc) into
volatile fatty acids (VFAs) which can be absorbed and utilised in respiration
*UCFM = Uncooked comminuted fermented meats
- 70% of ruminant energy → Gluconeogenesis (Propionate) and Ketogenesis
(Acetate and Butyrate)
Local Government
- A mandated role in food safety regulation
- Higher biological value microbial proteins made from low value plant
- Councils have nominated their degree of enforcement activity
proteins, non protein nitrogen and recycled products e.g. urea
- Enforcement activity publicly reported
- Vitamin B complex
- ‘Name and Shame’ list on the Authority’s website
- Nutritional meat and milk
Actions of the local government supported by the NSW Food Authority
- Inspections of facilities, packaging, food and preparation → search warrants
- Follow-up and investigations of food complaints
- Warning letters
- Power to administer improvement, penalty, seizure and prohibition orders
- Prosecution
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- Damaged tissue removed
Australian meat and dairy
- Quantitative and qualitative loss
- High local demand
- Withdrawal from the food chain
- Consumer confidence
- Good local quality
Milk safety
- Export leaders
On-farm actions to reduce risk
- Disease control
- Mastitis cases identified and milked last
- Free of FMD and BSE
- Mastitic milk not used for commercial milk production
- Eradicated of brucellosis & bovine TB
- Don’t transport sick animal to abattoir for commercial slaughter
- Johne’s disease control programs
- Diseased carcases will be condemned
- Good animal husbandry and farming
- Obey withholding periods for drugs used on animals
- Minimal use of antibiotics and hormones → less needed due to good
animal husbandry and management
- Hygiene, health management, housing, handling and feed
- Good animal husbandry
- Compliance with drug withholding periods
- Treat, quarantine/separate diseased/infected animals
- On-farm and off-farm, HACCP-based and industry support
- Monitor for disease, infected/contamination and food quality
- Dairy Australia → worked with FSANZ for a uniformed whole of chain dairy
standard
- Blood or tissue/fluid samples
- Milk samples
- MLA (SAFEMEAT)
- Local, state and national level of regulation and enforcement
- Faecal samples
- Food Standards Australia and New Zealand Code
- Environmental samples
- Meat quality
- Standard 4.2.3 – Meat
- Microbiological contamination
- Standard 4.2.4 – Dairy
Food safety
Mastitis
- Some infectious agents affect ruminants and humans
- Clinical mastitis → udder swollen, painful, clots and flakes in milk; often
chronic (long-term and recurrent, sub-clinical ! clinical)
- Transmitted in food → food-borne zoonosis
- Acute mastitis → Sudden inflamed mammary gland, abnormal milk, fever
- Food from diseased ruminants
- Sub-clinical mastitis → Subtle reduction in milk production, somatic cells
elevated
- Lower quality
- Reduced market price
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AVBS4004 | Food Safety Assessment & Management
- SCC (individual) , BMC (herd)
Mastitis pathogens
- Early stage of inflammation/infection → as significant or more so than
clinical mastitis = milk loss, milk composition and flavour, milk quality and
Streptococcus agalactiae
- 40 % of cases
safety, milk shelf-life, pathogen risk, chemical residues
- Sub-clinical common
- Contagious mastitis
Staphylococcus aureus
- 30-40% of cases
- Sub-clinical common
- Pockets of infection in the udder
- Recurrence common if not treated to cure
- Food safety
Environmental streptococci → S. dysgalactiae and S. uberis
- Poor hygiene and faecal contamination
- Teat dipping and milk parlour hygiene
Coliforms
- E. coli
- Environmental
- Food safety
Bacillus cereus
- Acute mastitis
- Environmental
- Food safety
Subclincial mastitis
- Somatic cell count (SCC) → Individual cow
- > 250,000 cells/ml (Bad)
- Bulk milk cell count (BMC) → Herd (bulk tank collection on farm)
- > 400,000 cells/ml (EU unsafe → cannot export)
Microbiological and chemical regulations for mastitis
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AVBS4004 | Food Safety Assessment & Management
- NSW food authority periodical testing and surveillance
- Wool length and rain — wet wool/dags provide the perfect environment for
pathogens → can be transferred from wool onto hide/meat during carcass
processing
- Twice a month, standard plate counts (SPC)
- >150,000 cfu / ml = Positive → REJECTION FROM FOOD CHAIN
- Feed can also influence gastrointestinal biota
- Factory testing of next pick-up
- Source of contamination / infection
- Failure of compliance note issued
- Can alter gut environment → microbial proliferation bias
- Testing until they make the grade
- Monensin → increase in % propionate producing bacteria
- Compliance and standard achieved to re-enter
- Antimicrobial resistant enteric microbes
- Antimicrobial residue
Risk reduction for enteric disease-causing pathogens
- Each tank
- Pasteurisation
- MRLs as per FSANZ
- Transport
- Standard 1.4.2 → REJECTED FROM FOOD CHAIN
- Meat inspection
- Notified Food Authority within 24 hrs → investigate farms
- Carcass washing and disinfection
- Withholding period abuse
- Evisceration and skinning → requires sanitised knives !!!!
Gastrointestinal disease
- GHP, SOP, QA
- Causes wasting, loss of energy, lower production yields
- Cold chain production, transport and storage of milk and meat
- Microbiological risk → infectious agents (i,e. Salmonella spp., EHEC and
- Recordkeeping and monitoring
ETEC)
- HACCP
- Chemical residues → from treatments
Johne’s disease
- Caused by a variety of non-infectious and infectious agents → some
infectious agents are harmful to human (e.g. E. coli - Rotavirus - Salmonella
spp. - Yersinia spp. - Giardia lamblia - Cryptosporidium parvum)
- Chronic inflammatory enteritis → wasting
- Mycobacterium avium subsp. paratuberculosis
- Many healthy ruminants carry these agents as part of their normal flora, or
because they have recovered from disease
- Link to Crohn’s disease?
- Difficult to diagnose and control: early exposure, long incubation period,
survives in soil
- Animal status can influence gastrointestinal health
- Age, pregnancy, stress, immunity and diseases
- Excreted in faeces and milk
- Susceptibility to GI disease → Proliferation of harmful microbes in the gut
- Notifiable disease
→ increased Excretion / shedding → Contamination of meat and milk and
risk
Food safety
- Crohn’s disease ???
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AVBS4004 | Food Safety Assessment & Management
- Pasteurisation (HTST) kills the pathogen in milk
- Heat resistant spores → proper disposal of carcass
Reproductive diseases
- If found at abattoir = CEASE OPERATION, destroy all meat, disinfect with
10% NaOH,
- Production importance: Number of animals → slaughter and harvest; Milk
production → cows need to give birth
Eradicated diseases
- Brucella abortus → brucellosis
- Q fever
- Pathogens can be transmitted in secretions
- Mycobacterium bovis (bovine TB)
- Milk
- Both where significant food-borne pathogens in unpasteurised milk
- Urogenital
Exotic diseases
- Contaminate meat
- Foot and mouth disease (FMD)
- Parasites can encyst in meat
- Not zoonotic
- e.g. Toxoplasma gondii and Sarcocystis hominis
- Transmissible spongiform encephalopathies (TSE)
Food safety
- Prion
- Management of feed: low silo pH = Listeria monocytogenes
- Long incubation period
- HTST for Q fever
- Always fatal
- Pest control: Cats (Toxoplasma) and ticks (Q fever)
- BSE, scrapie → Creutzfeldt Jakob’s Disease (CJD)
- Carcase inspection and handling
Pasteurisation of milk
- Freezing meats (many cysts are killed in meat below -20ºC)
- Cooking meats well
Staphylococcus aureus
- Eradication (Brucellosis)
- Strain variability in heat resistance ranging from 55°C - 68°C → require HT/ST
(High Temperature/Short Time)
Internal infectious diseases
- Enterotoxins are more heat stable than the cell
- Caseous lymphadenitis (CLA) → Abscess filled lymph nodes caused by
Corynebacterium pseudotuberculosis
- Pasteurisation will not inactivate the toxins
- Zoonosis risk in unpasteurised milk
- Infectious dose = 1 ng/ml of enterotoxin
- Management: avoid shearing when wet , disinfect shears, clean yards, avoid
dips, pasteurisation, meat inspection
Bacillus sp. (B. cereus)
- Toxins cause diarrhoea (diarrhoeagenic) and vomiting (emetic)
- Anthrax (Bacillus anthracis)
- Pasteurisation → vegetative cells destroyed but spores survive
- Sudden death and bleeding (toxins)
- Batch (LTLT) and HTST pasteurisation can trigger germination
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AVBS4004 | Food Safety Assessment & Management
- Diarrhoeagenic toxin is inactivated by pasteurisation
- Proliferative enteritis → Lawsonia intracellularis
- Emetic toxin is NOT (it is heat resistant)
- Malabsorption +/- diarrhoea
- Optimum temperature for toxin production is ~30°C
- Stress exacerbates
- Growth and toxin production can be prevented by maintaining milk at ≤
4°C → shock cooling milk at <4ºC.
- Faecal contamination of carcass
- Normal pig gut flora contains E. coli and Campylobacter
- Indirect public health risk
Disease and food safety: swine
and poultry
- Colibacillosis → Disease caused by E. coli
- Salmonellosis
- Campylobacterosis
- Yersiniosis
Pig and poultry disease control
- Can cause overt disease, often subclinical → Carried to slaughter
undiagnosed
- On-farm control methods
- Disease management and good husbandry
- Carriers → contamination
- Stocking rates, vaccination, worming and animal handling
- Yersinia enterocolitis → Pig tonsils primary source , take care in removing
during processing
- Animal movement (all-in/all-out)
- Feed, water and environmental controls
Control methods
- Biosecurity: workers
- At slaughter
- Growth promoters and antibiotics → withholding periods
- Separate overtly ill animals
- Off-farm control methods
- Do not allow entry to slaughter floor
- Transportation, handling and storage of food products
- Evisceration and hide treatment (washing or syncing)
- FSANZ standards 4.2.3 (pigs)
- Skin kept on most pigs
- Monitoring, testing and validating control measures
- Hot ‘knives’ and blowtorch
- On-farm and off-farm HACCP
- Meat and offal inspection
- Industry leadership: Australian Pork Limited → PigPass
- Carcass handling and chilling
Infectious disease in pork
- HACCP-based systems
Cook well and avoid cross-contamination
Gastroenteritis
- Control animal movement
- All-in/All-out, avoid overstocking
- Swine dysentery → Brachyspira hyodysenteriae
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- Health check in-coming pigs
- Withholding periods
- Vaccination and worming
- Biosecurity, disinfection and hygiene on farm
- Feed and stock biosecurity
- Don’t feed meat scraps to pigs
- Reduce stress and avoid overstocking
- Cook meat well or deep freezing
- Good hygiene practices
- AVOID EATING RAW MEAT
- Antibiotic use only when needed
Respiratory diseases
- Treat and isolated affected animals
- Major production issue
- Obey withholding periods
- Pathogens not a significant food-borne zoonotic issue
Parasites
- Management factors that predispose to respiratory disease:
- Giardia spp. and Cryptosporidium spp. → GI disease
- Indoor housing
- Poor ventilation
- Asymptomatic (carriers)
- Crowding
- Pig worms
- Causes:
- Often pigs appear healthy
- Mycoplasma spp.
- Pig tapeworm → Cystericercosis, Taenia solinum
- Encysted in meat
- Haemophilus parasuis
- Intestinal and non-intestinal disease in humans (def. host)
- Glasser’s disease
- Migrate to brain and encyst
- Actinobacillus pleuropneumonia → Often 2nd to viral infection → Lungs
condemned
- Pig roundworm → Trichinellosis, Trichinella spiralis
- Carcass condemned if extensive disease and involving other organs
- Encysted in meat
- Vaccines available for actinobacillus and mycoplasma infections
- Intestinal and then general disease in humans
Skin diseases
- Exotic to Australia
- Toxoplasma gondii → Cat invading pig sheds
Trimming and Bruising - Downgrading - Loss of carcase weight › Generally poor
grower - Lack fat › Pathogens not a significant food-borne zoonotic issue ›
Causes: - Pig pox - Staphylococcus hyicus - Greasy pig - Sarcoptic mange (is
zoonotic !) - Erysipelothrix rhusiopathiae - Diamond shaped skin lesions › Most
highly contagious - Spread rapidly
Control methods
- Meat inspection for tape and round worm
- Critical in EU and Asia where raw pork is consumed
- Antibody levels (ELISA, ante-mortem)
Control methods
- Worming pigs for tapeworms and roundworm ??
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Animal movement, hygiene and health, stocking density (avoid crowding) Vaccine for erysipelas
- Eviscerating bird involves removing all organs from an opening between
the legs = higher chance of contaminating carcass with faecal material
- Prophylaxis → Antimicrobial resistance significant public health risk
Poultry and food safety
- Off-farm control
Standards
- Carcase defeathering, evisceration, handling and storage
- The Australian Standard for Hygienic Production of Poultry Meat for Human
Consumption (AS 4465:2005)
- Eggs: harvesting, handling, cleaning, storage and processing
- Liquid eggs are pasteurised
- FSANZ 4.2.2 – Primary processing and production of poultry meat
- FSANZ 1.6.2 – Processing requirement standards
Salmonellosis
- FSANZ 2.2.2- Egg and Egg products standards
- Gastroenteritis in birds
- FSANZ 4.2.5 - Primary processing and production of eggs and egg
products
- Various Salmonella serovars including zoonotic serovars
- Salmonella Typhimurium (in Australia)
Colibacillosis
- Salmonella Enteritidis (Current outbreak in NSW!!)
- Asymptomatic carriers common
- E. coli → Gastrointestinal and respiratory disease
- Two principle routes of infection
- Reduced production value
- Increased contamination
- Trans-ovarian (vertical) → Salmonella Enteritidis phage type 4 (UK)
- Harbour strains that are harmful to humans - EHEC - ETEC - EIEC - APEC and
neonatal meningitis in children
- Trans-shell (horizontal) → Salmonella Typhimurium majority of egg-borne
illnesses
Control methods
Control methods
- Prevention on-farm
- On-farm
- Remove diseased birds
- Salmonella Enteritidis free status of hens
- All-in/All-out
- Bird movement, hygiene, feed, water, biosecurity
- Disinfect and re-stock with healthy birds
- Healthy happy birds
- Hygiene, drainage, ventilate, stocking and stress
- Minimise stress
- Reduce environmental burden
- Minimise faecal contamination
- Part of normal gut flora so can’t eliminate
- Prompt collection of eggs
- Diseased or stressed birds shed more
- Eliminate diseased animals
- Vaccine for S. Typhimurium serovar
- Vaccine → Poulvac
- Off-farm
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Other diseases
- Washing eggs with chlorinated water
- Ultraviolet treatment of eggs
- Chronic respiratory disease → Mycoplasma spp.
- Defeathering, evisceration, carcass washing, handling and storage
- Trans-ovarian and horizontal transmission
Egg pasteurisation
- All-in/All-out
- Cracked, small or misshaped eggs are used to produce egg pulp (liquid egg)
- Infectious coryza → Avibacterium paragallinarium
- They go through a pasteurisation process to reduce/eliminate microbial
contamination
- Poor hygiene, nutrition and ventilation
- All-in/All-out
- Pasteurised egg products must be free of Salmonella
- Improve management and housing
Salmonellosis egg outbreaks
- Fowl cholera → Pasteurella multocida
- Undercooked eggs or using raw eggs is the main reason we see egg
associated food-borne disease
- Older birds (layers)
- Vaccine – live atten. (VaxSafe® PM) is cross-protective
Campylobacteriosis
- Biosecurity (wild birds), animal and feed sources, hygiene
- Campylobacter jujuni
- Aspergillosis → Aspergillus spp.
- GI tract of birds
- Mouldy feed
- Most asymptomatic
- Respiratory disease
- Up to 90% infected in some flocks
- Mycotoxins can cause food-borne illness
- Most-common cause of chicken meat illness
- Control: Feed condition/security, Handling, washing/disinfecting, storage
Control methods
- Coccidiosis → Host specific Eimeria protozoa
- Control on-farm
- Difficult to be coccidia free flocks
- Hygiene and pest control
- Range of manifestations: diarrhoea
- Chlorinating drinking water → reduces gut burden
- Control: vaccine, prophylaxis in water, hygiene, stress, animal movement
and nutrition
- Control off-farm
- Minimise carcase and meat contamination
Bird flu — Avian influenza H5N1
- Defeathering, evisceration, handling, chlorinated washing → Minimise
microbial numbers
- Sudden death in birds (most of the time)
- Pathogenic enough to cause serious illness and death in humans: Mortality ~
- Temperature (cooking and cold chain)
50-70%
- Antimicrobial resistance is an issue
- Cannot be transmitted person to person
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AVBS4004 | Food Safety Assessment & Management
Control methods
- Hygienic production of ratite (emu/ostrich) meat for human consumption AS
5010 : 2001
- Manage wild bird vector
- Hygienic production of crocodile meat for human consumption AS
4467:1998
- Cook poultry meat
- Mass cull of infected flocks
Exotic food diseases and food safety
- Disinfecting cages, equipment, vehicles used to transport and clothing
- Notifying authorities BIOSECURITY
Rabbit
Botulism
- Q fever
- Clostridium botulinum → Ubiquitous spore forming Gram +ve anaerobe rod,
found in GI tract and soil
- Yersinia → Faecal or secretions on hide and carcase
- Causes acute diarrhea, mesenteric adenitis, terminal ileitis in humans →
sometimes sepsis and death
- Present in decaying vegetative materials (pH>5, moist, anaerobic)
- Protoxin released in feed by lysis of cell
- Tularaemia (Rabbit fever) → Francisella tularensis
- Protoxin ingested and activated by trypsin / proteolytic cleavage and
absorbed
- Insect vectors
- Systemic not in the gut
- Toxin binds to neuromuscular junctions → flaccid paralysis + death in birds
- Lethal
- Humans experience dizziness, abdominal pains, trouble breathing and
respiratory arrest
- Wild rabbits and other wildlife
Control measures
Control methods
- Cook meat well
- Low temperature storage (stop proliferation)
- DO NOT harvest sick looking rabbit
- Heating food to >80º for 15 minutes (inactivates the pre-formed toxin)
- One case in NT 2001 associated with tick transmission, second case in
Tasmania (2010) associated with a possum bite
Disease and food safety:
seafood and exotics
Frog
- Aeromonas hydrophila - “Red leg”
- Enterotoxins food hazard
Standards
- Bacteria is psychrotrophic (‘cold’ lovers)
- FSANZ Standard 4.2.1 (Seafood)
- Salmonella spp.
- Game meat for human consumption standards AS 4464:2007
- Faecal carriers
- Production of rabbit meat for human consumption AS 4466 : 1997
- Often present on skin
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AVBS4004 | Food Safety Assessment & Management
Control measures
- Snail meat regulations for composition and residue limits
- Chlorinated water
Kangaroo
- Irradiation of frozen frog meat for export
- Sarcocystis
- Water-borne pathogen control in food
- Intracellular protozoan parasites
Snails
- Muscle encysts and damage
- Edible snails → Helix spp.
- Unknown if definitive host is man → Food hazard ??
- Intensive or ‘free-range’ on pasture
- Salmonella
- Aeromonas hydrophila
- Caused Russia to ban imports
- Sloughing
- E. coli
- Enterotoxins food hazard
- Toxoplasma gondii
- Bacteria is psychrotrophic (‘cold’ lovers)
- Encysts in muscle tissue
- Carry salmonella and protozoa
- Pregnant women at risk
- Flukes (Trematodes) → Fasciolopsis buski
- Cook meat well
- Leptosporosis (L. interrogans) & Q fever
- Infects the duodenum and jejunum in humans
Control measures
- Contact transmission → Urine splashing, abattoir workers
- Good hygiene, especially water
- Possible contamination of meat through exposure to infectious secretions
- Feed and soil management: earthworms
- Urine main source and faecal
- Temperature and humidity
Crocodile
- Chlorinated water
- Salmonella
- Avoid overstocking
- Various serovars of human significance
- Pesticide control important → residues in snail meat an issue
- Enteritis
- Condemn diseased snails
- Hatchlings → Exudative and blockage, constipated croc
- Cook snails well → May not affect heat stabile enterotoxin
- Recovery and carrier status
- Irradiation of exported snails suggested
- Coccidiosis
- HACCP-based systems
- Malnutrition and diarrhoea
- Quality assurance
- Increase faecal shedding
- Farm management and food processing - “whole-of-chain” farming
- Stress and overcrowding
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AVBS4004 | Food Safety Assessment & Management
- Hygiene and prophylaxis medication
Zoonoses
- Trichinellosis
- Infectivity in human unknown
Definitions
- Difficult to detect at meat inspection (no diaphragm)
Zoonoses — Diseases caused by infectious agents that can be transmitted
between animal and human.
- Seen in PNG → import restrictions
Control measures
Anthropozoonoses — Pathogen transmitted from animal to human
- Water hygiene and treatment
Zooanthroponoses — Pathogen transmitted from a human to an animal
- Biosecurity
Amphixenoses — Pathogen transmitted in either direction or shared between
humans and animals
- Feed sources
- Skinning and evisceration
- Chlorinated washing of carcase or hot water washing
Pseudozoonoses — Disease that people believe can be transmitted from an
animal to a human but can’t
- Crocodile approved abattoirs
Host — Living thing capable of being infected
- Hygienic production of crocodile meat for human consumption
Carrier — Infected host who is a potential source of infection to others (can be
vectors, fomites etc.)
Seafood diseases and food safety
Definitive host — Maintains the infectious agents in nature
- Fish are far distant relatives to human
Intermediate host — harbours the infectious agents for a short period of time
undergoing limited development or multiplication
- Seafood pathogens do not present direct food safety concerns
Paratenic host — The infectious agents is transferred mechanically, without any
development
- Can accumulate pathogens excreted in human faeces
- Molluscs (Filter feeders)
Reservoir host — The infectious agent is naturally found and has no ill affect
- Sewage / pollutant waters → Presents the greatest food safety risk
Amplifier host — Concentration of the agent can suddenly increase
- Norovirus
Incidental (accidental) host — Does not transmit the infectious agent to other
- Hepatitis A & E
animals or man → often called a ‘dead end host’
- Cholera → Vibrio cholerae
Direct transmission — Susceptible individual has physical contact with infected
host or infectious secretions
- Marine phycotoxis → Variety of seafood toxins associated with ingested algae
and phytoplankton
Indirect transmission — No direct physical contact between susceptible
individual and infected host or infectious secretion (via vectors or fomites)
29 August 2019
Zoonotic agents
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AVBS4004 | Food Safety Assessment & Management
• Mainly viruses
• Inhaled
• Many human infectious agents have animal origins
• Localised disease → e.g. Gastroenteritis from ingestion
• Zoonoses represent ~ 80% of infectious diseases in humans
• Systemic disease → Spreading throughout the body - Blood and lymph
• Ones of economic importance: Anthrax, Bat Lyssavirus, Q fever, Hendra
• E.g. Rabies
virus, Chlamydiosis, Arboviruses, Toxoplasmosis, Leptospirosis, Influenza
• Through saliva + bite wound
• Most animals are zoonotic sources
• Neurotrophic → targets CNS
• ~ 40% of zoonotic pathogen from carnivores
• Fatal
• ~ 40% from ungulates (hoofed animals)
• E.g. Cat scratch disease → Bartonella hensalae
• ~ 20% from rodents
• Bacteria
• ~ 10% from birds
• Asymptomatic in cats
Emerging zoonotic diseases
Indirect
• Living vehicle that transmit the infectious agent from the infected animal to
• 75% of emerging diseases are zoonotic
the susceptible person
• When they appear, they can spread rapidly → Naïve human population
• Commonly arthropods → Insects, ticks, mites and flea
• E.g. west nile virus outbreak in US in 1999 affects humans and horses
• Other animals of differing species
• 2011 Kunjin virus in Australia (related to WNV) did not have as big of a
• Mechanical
consequence
• Biological - Arboviruses (e.g. WNV, JEE)
H1N1 Influenza pandemic
• Non-living (fomite)
• Epidemiological link to birds and pigs
• Inanimate object → Blankets, clothing, kitchen utensils
• Triple hybrid virus → reassortment of swine, bird and human flu
• E.g. ringworm from infected bedding
• Antigenic shift → reassortment
• Food-borne disease due to crosscontamination
Transmission
• E.g. listeria from meat slicer
• Water, food and air
Direct
• Touching, biting, contact with infected secretions or droplets through
Food-borne disease transmission
animal’s coughing and sneezing
Direct → Ingest an infected animal or secretion from an infected animal
• Enter the body
Indirect → Transferred due to food/animal handling, practices and processing
e.g. contamination with faecal material
• Breaks in skin
• Ingested
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AVBS4004 | Food Safety Assessment & Management
Changing in farming practices
Factors contributing to zoonoses
• Intensive farming → Development and spread of infectious disease; speeds
Environmental changes
up evolution of pathogens
• Temperature, rainfall and soil
• Antimicrobial growth promoters → Antimicrobial resistance
• Climate change
• Feeding farm animals, animal-based proteins → Circulation of animal
• Warmer summer weather in Canada
pathogens
• Tick vector (Ixodes spp.) can survive further north
Sociocultural factors
• Infecting wildlife and people in new regions
• Consumer demands → Low salt foods; Ready-to-eat foods; Fast food culture
Human and animal demography
• Cultural and religious practices → Home made food; Raw food consumption;
Animal sacrifice
• Migration patterns of birds → domestic animals and humans
• Consumer adventure → Game meats; Undercooked and raw foods
• Wildlife encroachment into human and farm animal habitats → e.g. Flying
foxes and Hendra virus in horses and man in QLD/NSW
• Consumer ignorance → Cooking, storage, handling and preparing food;
Microwave cooking
• Humans encroaching into new areas → ‘First encounter’ zoonotoic event —
e.g. Ebola virus → jungle encroachment
Prevention of zoonoses
• Living with animals
• e.g. Shared poultry/human households → Avian Influenza in Asia
• Pathogen - Animal - Human - Vectors - Environment interactions
• e.g. Cat Scratch Disease and Ringworm in urban Australia
• 3 basic measures
1. Reduce or eliminate source of infection
Pathogen change/mutation
2. Reduce the number of susceptible humans
• Evolving pathogen
3. Break the connection between the zoonotic source and susceptible
humans
• Mutations
• Recombination and gene transfer
Reducing/eliminating source
• Evolution through selective pressures → e.g. Antimicrobial resistant strains
• Change in virulence or other properties
• E.g. eradicating Brucellosis in cattle
• Survival → e.g. Acid & heat tolerance, Heat tolerate
• Product recalls
• Transmission
• Cull animals reservoirs → e.g. wild birds/bats
• Replication
• Disposal of infected animals → burning
• Disease manifestation and treat-ability
• Vaccination of animals → e.g. rabies, leptospirosis
• Variations allow immunoevasion
• Quarantine
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AVBS4004 | Food Safety Assessment & Management
• Treat animal until cured
• Activities, records, verification and validation
• Eradication programs
HACCP
Reducing number of susceptible humans
• E.g. vaccination of humans
Hazard Analysis Critical Control Point (HACCP)
• Few vaccines for zoonotic diseases → Rabies, JE, Q Fever
• Science based and systematic identification of hazards and measures for their
control throughout the food chain
• Expose humans → protective immunity
• Recognise events or practices at critical points in the food chain
• E.g. toxoplasmosis → early exposure = lifelong antibody response =
protective immunity when pregnant
• Establish critical food safety limits at these points → Critical Control Points
(CCP) (needs to be measurable)
Breaking the source-human connection
• Critical Limits (CLs) to ensure minimum risk
• E.g. pasteurisation
• Targeted corrective measures to reduce risk
• Avoid contact with diseased/carrier animals
• Audits, monitoring, quality control
• Chlorination of water supplies
Risk
• Pasteurisation of milk and liquid eggs
• Ultraviolet treatment of eggs
• RISK = Likelihood and consequence
• Carcase and meat handling → Evisceration, skinning and chilling
Risk assessment
• Avoiding contaminating → Cooked with uncooked, raw with treated
• Scientific evaluation of effects due to exposure to a hazard
• Hazard Identification: Specific agent
• Food preparation and storage → Temperature, time, placement and cooking
• Hazard characterisation
• Destruction of insect vectors with pesticides → Insect repellant and
• Qualitative and quantitative description of the consequence of exposure
protective clothing
• Dose response assessment → infectious doses and lethal doses
• Reducing exposure for young, immunocompromised and elderly
• E.g. E.coli low infectious dose VS Bacillus cereus high infectious dose
HACCP (Hazard Analysis and Critical Control Points)
• Principles of disease control and prevention
• Exposure assessment → Evaluation of the likely degree of intake - Relevant to
CCPs and CLs
• Breaking the connection
• Risk characterisation → Estimate of likely effects as a result of exposure — i.e.
• Identifying pathogens (Hazards)
Severity x Exposure
• Control measures to reduce risk associated with these pathogens → critical
Risk analysis
limits + standards
• Critical control points
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AVBS4004 | Food Safety Assessment & Management
• Integrated into HACCP design
• Risk management
• Risk communication
7 principles of HACCP
• Goals
• Food chain management and control of hazards: Science, practices ,
informing
• Activities that reduce risk of food-borne disease
• Consumer confidence and well-being
Developing a HACCP plan
1. Assemble the HACCP team
2. Describe the food and its distribution
3. Identify intended use and consumer of the food → In-depth understanding
of the product, intended use and consumers and their behaviour
4. Develop production flow diagrams
5. Verify flow diagrams
6. Conduct hazard analysis
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AVBS4004 | Food Safety Assessment & Management
1. Conduct a hazard analysis
• How frequently does it need to be tested?
• Prepare a list of steps in the food chain and identify the potential hazard(s)
• What is tested?
at each step, assess likelihood of occurrence and identify preventative
measures (Biological, chemical, physical)
5. Establish corrective actions
• What to do when monitoring indicates there is a deviations from
2. Identify the critical control points
established CLs
• Point, step or procedure at which control can be applied and a food safety
• Determine the nature of the non-compliant product
hazard can be prevented, eliminated or reduced to acceptable levels
• Fix the cause of non-compliance to assure CCP is under control
• Need to be able to quantify or measure hazards e.g. Temperature , time, pH
• Record corrective actions taken where there has been a deviation from
• Needs to have a quantifiable response to corrective action
CLs
3. Establish critical limits (CLs)
6. Establish effective recordkeeping procedures
• Use a CCP Decision Tree
• Establish effective recordkeeping procedures that document the HACCP
system
• Confirm HACCP system is working effectively
• Internal and external checks
7. Establish verification procedures
• Establish verification procedures that the HACCP system is working
correctly
• HACCP Plan is a dynamic instrument
• Role of outside audits and experts → Review process to determine if
• SOPs (standard operating procedures) and GMPs (good manufacturing
significant changes have occurred
practices) are often said to be prerequisites for HACCP and can be applied
at points which are said to be less critical in food safety or within the
structured activity at a given CCP
• Confirm CCPs are under control → Quality control testing
• Determine if there are new hazards
Quality assurance
• Critical limits for preventative measures associated with each identified
CCPs
• Application and verification of control measures
• E.g. temperature, time, animal status (age, disease, pregnancy, grade etc.),
• Ensure food safety and compliance with regulatory or customer requirement
food composition (pH, salt, water etc.), microbiological counts (e.g. E.coli
<100 CFU)
→ Activities at CCPs and less critical points
• Planned and obtained by implementing Standard Operating Procedures
4. Establish CCP monitoring requirements
(SOPs) at various steps along the food chain
• Who monitors and tests? Accreditations?
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AVBS4004 | Food Safety Assessment & Management
• Complementary HACCP-based systems
• Reduction in cross-contamination → Treat and raw foods, carcass storage and
processing
• Good Hygiene Practices (GHPs)
• High standards in processing foods → Australian Standards, FSANZ and
• Good Management Practices (GMPs)
AQIS, Microbiological standards
• Quality control = testing
• Retail and consumer practices → Temperature, packaging and preparation
• Temperature - “Danger zone”
• pH → Fermented food
• Water activity (aw) → dehydrated, hard vs soft cheese etc.
Exposure and pathogen factors
• Dose → The more present in raw food the more likely to survive treatment at
CCPs
• Resistance to: Heat, Desiccation, Low aw, Drying, Salt tolerance (e.g.
Staphylococcus aureus), Disinfection, Acid (low pH; Strains of enteric
pathogens are acid tolerant)
• Psychrotrophs (cold lovers) and thermophils (warm lovers)
• Psychrotrophs more of an issue as can grow in the fridge
• Listeria monocytogenes in soft cheeses, yoghurt and unwashed fruits and
vegies
HACCP for reducing microbial
food-borne diseases
• Survival in biofilms → Bacteria in protective matrix — Resistant to disinfectants
→ Difficult to culture unless the biofilm is seen and sampled
Exposure and host factors
General control measures to reduce risk of microbiological
pathogens in food
• Consumption patterns → Fast food, Packaged/prepared food, Religion and
cultural habits
• Susceptibility
• Prevent entry onto farm → biosecurity (animal, feed and water), quarantine
• Young/old/immunocompromised
• Eliminate or reduce prevalence → Treat and cure, Infectious disease control,
• Antibiotics, concurrent diseases, pregnancy, antacids
On-farm hygiene and stock management , Animal husbandry practices
• Genotype → genetic predispositions
• Reduce stress → Improve environment
Factors affecting survival and growth of microbes in food
• Quality assurance at the primary processing level
• SOPs, GHPs and GAPs ON-FARM
• Temperature
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AVBS4004 | Food Safety Assessment & Management
• Water availability → (water activity = aw)
• Ground or chopped meat below 5°C
• pH → Acidity and alkalinity
• Microbiologically high quality → Low TVC (total viable count) or E. coli per
gram
• Irradiation → Ultraviolet, ionising
• Addition of “starter culture” → PURE → No “backslopping” (recycling cultures
• Curing → Salt or Smoke
from a previous batch)
• Antibiotics
• Addition of salts, sugars, antioxidants and species → Lower aw
• Packaging → Gas flushing (eg. CO2 ), modified atmosphere packaging
• Quality testing of additives needed
• Sanitation (cleaning)
• Encasing and fermentation → 15-25°C depending on starter culture, 80%
• Disinfection
humidity, 2-3 days, pH monitored
Food preservation
• Drying/smoking → Lower aw , 50% humidity for at least 10 days = aw<0.92
• Food preservation methods work by reducing bacterial proliferation and
E. coli and food safety
microbe survival
• Modification of food factors
• Many strains of E. coli found in food are harmless → but are an indicator
organism
• Heating
• Freezing
• E. coli in the GIT of an animals is diverse and mixed
• Dehydrating
• Most significant pathogenic E. coli associated with food-borne disease is:
• Enterohaemorrhagic strain types (EHEC)
• Fermentation
• E. coli O157:H7 most well known (does not cause disease in animal)
• Chemical preservatives
• Humans infectious dose is low → ~10 CFU per child can cause infection and
• Irradiation
disease
• All act to prevent/reduce spoilage organism and in most cases also impact
E. coli O157:H7
upon pathogen levels
Uncooked fermented meat (UCFM)
E. coli O157:H7 in animals
• Salami and Mettwurst etc.
• Asymptomatic carriers
• Fermentation → Acid production by bacteria → pH<4-5 → kills most
pathogens
• Young weaned cattle shed more
• Extent of fermentation needed for safe UCFM? → Depends on the condition
• Sheep and deer less frequent
of the food
• Confined to the GIT → Frequency of excretion varies → Faecal shedding can
• Lowest (most acidic) in high moisture products
be intermittent and short duration
• Addition of salts, nitrites and drying/smoking (pH need not be so low)
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AVBS4004 | Food Safety Assessment & Management
• Postweaning → “Supershedders” → More frequent and higher concentration
• Low infectious dose resulting in severe disease
• Identification
• Focus on reducing and eliminating organism from food chain rather than
preventing pathogen growth
• Stress → Fasting may increase shedding; High grain diets may increase
• Particularly important with non cooked or improperly cooked food
shedding (Changes gut microflora and impacting upon O157:H7 dynamics)
• Heat will kill, few opportunities in the meat chain to eliminate...
E. coli O157:H7 in man
• HACCP still a major means to reduce risk from E. coli
• Clinical disease in humans
• Verification through microbiological monitoring
• Incubation period 1-2 days for GI symptoms
• Generally some tolerance to detectable E. coli in raw meat
• 4-10 days post GI for systemic symptoms
• >100 CFU/cm2 or /g = Marginal / unsatisfactory and prompts
• Children and elderly most at risk of systemic symptoms
investigations
• GI symptoms: Mild non bloody diarrhoea, Cramps and fever → Overt bloody
• Most desirable is a lethal step in the food chain
diarrhoea, Severe abdominal pain and dehydration
• Cooking
• Systemic effects of the toxin (Shiga-toxin, Stx)
• Pasteurisation
• Haemolytic uraemic syndrome (HUS)
• Fermentation
• Intravascular haemolysis and thrombocytopaenia (TTP)
• pH tolerance range (in meat) is 5.5 -7.5
• Oligouria, oedema and renal failure
• UCFM FSANZ standards states that a 3-log reduction in E. coli is desirable
(99.9% reduction)
Foods associated with E. coli O157:H7
• pH<5.3
• Associated with food of ruminant origin
• Acceptable is 3.6 E. coli CFU/g
• Most outbreaks associated with poorly cooked ground beef
Farm-level control
• Fermented and dry meats
• Reduction of carriage → Detection of supershedders ??
• Unpasteurised fruit juices
• >104 E. coli 0157:H7/g
• Vegetables in contact with effluent from cattle
• Good husbandry condition
• Raw milk
• Food sources free from contamination
• Yoghurt
• Clean water sources and feed bins
• Water
• Reduce stress from handling, transportation and concurrent disease
Control of E. coli O157:H7
• Probiotics?
• Despite HACCP approach still see disease because:
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AVBS4004 | Food Safety Assessment & Management
• Vaccines → Type III secretion protein (part of the flagella) = 3-4 log reduction
in secretion and reduced frequency (up to 90%) but not being taken up by
farmers (no economic benefit / incentive)
Abattoir-level control
• Focus on reducing faecal contamination
• Evisceration and skinning procedures → Clean lairages (holding pen)
• Minimise stress associated with handling
• Trimming visible contamination
• Knives and equipment hygiene → Hot water sanitises → Acid washes
• Quarantine
• Steam vacuuming can result in 5 log reduction
Control: food-processing
• Snap freezing (-18°C) can result in 1-2 log reductions → Most exported
ground meat are exported frozen
• Proper production procedures and appropriate storage
Monitoring carcasses
• Ground meat → Mixing and distribute the pathogens → Use the highest
microbiological quality possible (<10 CFU/cm2)
• Quantitative
• Usually not specific to strain type in abattoirs
• De-boning
• Ground meat for export will use a E. coli O157:H7 PCR Qualitative (+/-)
• Additives
• Carcase swabbing (done post chilling - After it reaches 7°C surface)
• Certified free of E. coli
• Final result is expressed as CFU/cm2 or /g or /ml
• Fermentation of UCFM → Meets pH requirements
• CL for carcase or ground meat = 100 CFU/cm2 or /g → Above this CL alert,
• Drying - Meets aw requirements <0.85-0.88 aw
recall and investigation
• Validate effectiveness of procedures
• Pasteurisation of liquid → Heat kills >60°C for 1 min
• Food irradiation → 1.5 – 3 kGy
• Commercial sterilisation - Canned meat
Control: at home
• Cooking
• Cook ground beef thoroughly before eating
• Cross-contamination
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AVBS4004 | Food Safety Assessment & Management
• Raw meat or vegies with cooked
• Cold chain (CL, 3-4ºC within 1 minute of pasteurisation and storage)
• Washing hands
• Packaging
• Caring with someone with diarrhoea
• Cooking (CLs)
• Handling cattle
Yoghurt HACCP
• Gardening
• Microbial hazards: Salmonella spp. and other enteric bacterial pathogens,
• Infected humans can be a source → Takes up to 48 hrs for symptoms & can
e.g. Staphylococcus aureus (toxins), Listeria monocytogenes
excrete up to 3 weeks post recovery: SHOULD NOT PREPARE or HANDLE
FOOD
• Critical control points:
• On farm as per milk → Milk processing
Oyster HACCP
• Pasteurisation (CLs)
• Microbial hazards: Hepatitis virus, Norovirus , Vibrio spp.
• Fermentation (CLs – pH ≤4.5) → pH ~4 will inhibit Listeria growth
• Critical control points
• Flavours and additives
• Harvesting from water sources
• Storage and transportation → Cold chain (CLs)
• Timing and location
• Containers
• Algal blooms and sewage overflow
• Cross contamination and hygiene
• Testing for coliforms in water (CLs)
• Use by date (CLs)
• Post-harvest handling and storage
5th September 2019
• Chilling (CLs, temp. and time)
• Water treatment
Gastrointestinal zoonoses
• Personal hygiene and handlers health
Egg HACCP
Definitions
• Microbial hazards: Salmonella Typhimurium, Mycotoxins
Infectious dose → Number of organisms to establish an infection
• Critical control points:
Infection NOT EQUAL TO Disease
• Egg collection → Timing and frequency (CLs)
• Cleaning → Sanitisation/UV treatment (CLs)
Incubation period → Time between infection and first signs of clinical
symptoms
• Handling → Automation (caged birds)
Communicable period → The time during which the infectious agent may be
transmitted between hosts (animal and man) → “Infectious or contagious” i.e.
the time when disease can spread between animal and human hosts
• Processing → Egg sorting, Cracked eggs
• Liquid eggs → Pasteurisation (CL for Salmonella - 65ºC for 3.5 min)
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AVBS4004 | Food Safety Assessment & Management
- Facultative anaerobe
Notifiable disease → Any disease that by law is required to be reported to
government authorities
- Temperature: 7-48ºC, ideal 37ºC
- Serious in nature, significant outbreaks and significant health risk
- Best at pH = 6.5-7.5, can grow as acidic as 4.1
- Many are highly contagious
- Survive in dried food
- Many are zoonotic and food-borne
- Heat sensitive
- Many are exotic to Australia
Source
- National Notifiable Disease Surveillance System (NNDSS)
- Intestines of endothermic and ectothermic animals
Common gastrointestinal agents of disease
- Particularly birds and reptiles (constantly exposed to their own faeces)
Viruses - Rotavirus - Norovirus › Bacteria - Salmonella spp. - Campylobacter spp.
- Yersinia spp. - Escherichia coli - Bacillus cereus - Vibrio spp. - Staphylococcus
aureus › Protozoa - Cryptosporidium parvum - Giardia lamblia › Parasitic worms Ascaris spp. - Trichinella spiralis
- Poultry and eggs
- Not always disease in animals
- Shedding can be brief or lifelong
Salmonellosis
- Latent infection
- Carriers and subclinical are significant sources
- Gram negative rod (Enterobacteriaceae)
- Antimicrobials prolong shedding
- Non-lactose fermenter
- Infectious dose can be low: 10-10^5 CFU
- >2000 different Salmonella serovars → About 35 account for the majority of
illness
Transmission
- S. Typhimurium
- Ingestion of faecally contaminated food + undercooked/unpastuerised
products
- S. Typhi
- = Typhoid in humans (Enteric fever)
- Trans-ova
- Specific to humans not a zoonosis
- Cross-Contamination of food (flies!)
- Poor hygiene during food preparation and handling
Pathogenesis
- Gastro → Septicaemia
- Penetrates into epithelium of SI and passages through the GIT →
Inflammation (from Enterotoxins)
- One of the leading causes of food-borne disease in Australia each year
Salmonella spp.
- Incubation period: 6-72 hours
- Clinical signs
- Motile (Flagella H antigenic)
- Diarrhoea +/- blood
- LPS on cell surface (O antigens)
- Abdominal cramps
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AVBS4004 | Food Safety Assessment & Management
- Fever
- Reduce stress
- Self-limiting (antimicrobials don’t help)
- Hygiene and water security → chlorinated water
- Complications: Reactive arthritis, septicaemia
- All-in/all-out production systems
- Treatment: Supportive, antibiotics if septicaemic
Campylobacteriosis
Treatment and control
- Most common notifiable disease → mostly young children
- Hygiene for workers and food handlers
The pathogen
- Correct meat storage
- Cooking/pasteurising meat and eggs
- Campylobacter jejuni
- Don’t eat unwashed/cracked eggs
- Spirally curved microaerophillic gram negative rod bacterium
- 10% CO2 and low O2 tension
Poultry meat
- De-feathering hoods
- Single polar flagella
- Carcase wash with chlorinated water
- Temperature: 37-45ºC, no growth <25ºC
- Rapid refrigeration
- Survives to 4ºC
Meat
- Heat sensitive
- Evisceration and skinning
- Sensitive to drying and salt (>2%NaCl)
- Cold-chain
- pH: 6.5 – 7.5
Eggs
Source
- Collected frequently (on-farm)
- Found in GIT of many animals incl. humans
- Cleaned of dirt
- Poultry, dairy and beef cattle and sheep
- Ultraviolet irradiation
- Cracked and dirty eggs :(
- Pigs carry this species and a high proportion of C. coli (not a significant
zoonoses but can transfer antimicrobial resistance to C. jejuni)
- Pasteurisation of liquid eggs → Make sure eggs are boiled completely (fully
- Raw milk common source of food-borne
cooked yolk)
- Does not survive pasteurisation (HTST or LTLT)
On-farm
- Contaminated water → Almost all chickens are contaminated with C. jejuni
- ID and eliminate carriers
- Asymptomatic carriers common in animals → Occasionally in humans too
- Clean feed sources
Transmission & pathogenesis
- Vaccinate → e.g. VaxSafeST for S. Typhimerium in Australian poultry
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AVBS4004 | Food Safety Assessment & Management
- Ingestion → Faecal contamination of food and water
- Water treatment → Chlorine and microfilters
- Infectious dose: Low ~ 500 CFU per person
- Control proliferation in food → Temperature and time abuse / Heating and
freezing
- Incubation period: 2-10 days
Cryptosporidiosis
- Communicable periods: Animal is infected (days, months or lifelong)
- Humans can transmit for up to 2 month if not treated
- Coccidia Protozoa
- Asymptomatic carriers for longer periods rare in humans
- Coccidia parvum
- Clinical signs → Mild diarrhoea to severe gastrointestinal distress; fever;
abdominal pains and bloody diarrhoea
- Obligate intracellular parasite
- Colonises the small and large intestine causing inflammation and mild
ulceration → Toxins
- Cannot replicate in food
- Complications: Reactive arthritis, Guillian-Barre syndrome (serotype O19),
Source
- Notifiable
HUS (Hemolytic uremic syndrome)
- GI tract of a wide variety of animals
- Treatment: Self-limiting → Recover in <1 week without treatment
- Juveniles esp. calves
- Supportive therapy, Antibiotic in severe cases esp. Young and elderly
- Asymptomatic carriers → Juvenile and sometimes adults
Prevention and control
- Public swimming pools
On-farm
Transmission and pathogenesis
- Widespread nature
- Ingestion (faecal-oral)
- Asymptomatic carriers
- Faecal contamination of food and water
- Chlorinate water → Reduce gut burden
- Person-person propagates outbreaks (due to poor hygiene)
- Hygiene and pest control → Prevent exposure
- Infectious dose: <100 oocysts
Off-farm
- Oocysts are highly resistant in natural environments → Contain ‘zoites’ that
invade the intestinal epithelium when ingested
- Hygienic practices
- - Avoid faecal contamination of carcase
- Can survive in moist soils and water for 6 months
- - Cross-contamination
- Incubation period: 4-12 days
- Raw meats and milk
- Communicable periods: Diseased animals or carriag; diseased humans or
- Pasteurisation ✓
carriage → several weeks after recovered
- Freezing meats –18ºC
- Clinical signs: Watery diarrhoea
- Irradiation
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AVBS4004 | Food Safety Assessment & Management
- Self-limiting: 1-2 weeks
- Avoid faeces
- Young and immunocomprimised most susceptible
- 80ºC water
- Crohn’s disease can complicate = Life threatening
- Evisceration, skinning and defeathering
Prevention and control
- Avoid faecal contamination of carcase
Colibacillosis
- Treatment: Self-limiting; supportive; Nitazoxanide
- Early in young and immunocompromised
- Escherichia coli (Enterobacteriaceae)
- Severe cases still under review
- Gram negative facultative anaerobic rod
- Difficult, no vaccine
- Lactose fermenter
- Limit exposure through good hygiene
- Normal inhabitant of the intestine of all animals and humans
- Heat and Freezing: >60ºC - -20ºC
- A minority of strains cause illness
- Resistant to disinfectants → Survives standard water chlorination = need
hyperchlorinated water
- O antigen → LPS (lipopolysaccharides on cell wall)
- H antigen → Flagella
- Drying and Steaming
- Growth: 37ºC and pH=7 (optimum)
On farm
- Growth can occur at temperatures as low as 8ºC → Survive refrigeration
- Raising newborns in clean, dry environments → Reduces likely exposure
- ph range 4.4-9.0 → Acid tolerant
- Separating healthy from sick
- Growth at 6.5% NaCl
- Workers segregation to prevent crosscontamination
- Heat-sensitive: >65ºC
- Age separation (e.g. bobby calves on the dairy)
- Rotations
Pathogenesis
- Faecal clean up
- Diarrheoa +/- others
- All-in/All-out
- 3 main strains cause illness
- Health certificate replacement animals
- Enterotoxogenic E. coli (ETEC)
- Screen for C. parvum
- Enteroinvasive E. coli (EIEC)
- Water security
- Enterohemorrhagic E. coli (EHEC)
Off farm
- Incubation period = 1-10 days
- Pasteurisation
- Most significant and pathogenic zoonotic E. coli
- Water security and temperature
- Notifiable
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AVBS4004 | Food Safety Assessment & Management
- E. coli O157:H7 major case of severe gastroenteritis in contaminated meat
- HTST pasteurisation
Source
- Chlorinated water
- Meat processing: carcase treatment and storage; evisceration and skinning
- From animal-human, food-human, human-human
techniques; hygiene; chilling (just prevents proliferation)
- Cattle mainly → Calves and young cattle (6-24 months of age)
- Monitoring of bacterial load in meat
- Deer and sheep (occasionally birds, pigs and horses)
Norovirus
- Many are asymptomatic carries of these pathogenic strains as part of their
normal flora
- Non-enveloped single stranded RNA virus
- Stress and feed type (grain/barley) may increase excretion → Supershedding
- Norwalk-like virus, Calicivirus, Small Round Structured Viruses (SRSVs)
- Infectious dose: low ~ 10-100 CFU
- Survives freezing and heating (<60º C)
- Communicable period: animals can be lifelong, periodic & seasonal
- Causes acute gastroenteritis in humans
shedding, humans can secrete >3 weeks post-recovery
- Faecal-oral transmission → Primarily associated with seafood
Transmission
- Filter-feeding molluscs and prawns accumulate virus from contaminated
water
- Faecal-oral
- Post-harvest or slaughter contamination of food
- Contamination of food
- Poor personal hygiene
- Undercooked, contaminated beef
- Primary source → Human faeces and contaminated water sources
- Contamination of the carcase surface → Ground beef = Mixing and
spreading the pathogen + Increase surface area aiding in proliferation
- Not notifiable
- Water can carry it into the food chain
- Everyone is susceptible → No lasting immunity!!
- Meat and vegetable
Clinical signs
- Fruit and veggies grown in contaminated soils
- Self-limiting
- Poor hygiene during processing of meat
- Nausea → Projectile vomiting and lots of watery diarrhoea
- Kitchen cross-contamination
- Fever and headaches
- People to people spread
- Treatment → Symptomatic and supportive
- Direct transmission from animals (e.g. petting zoo)
Incubation period
Prevention and control
- 10 - 50 hours
Communicable period
- Cook meat → 72ºC for 2 mins sufficient for EHEC strains
- Humans infectious for up to 48 hours after diarrhoea ceases
- Fermentation
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AVBS4004 | Food Safety Assessment & Management
- Can persist for up to 2 weeks
- Faecal contamination of food
Infectious dose
- Poor hygiene
- Unknown
- Contaminated water → esp. proliferation during algal blooms
- ~ 100 viral units ??
- Use of contaminated water in food processing and preparation
Prevention and control
- Communicable periods: People are infectious during the acute stage and for
a few days after and are occasionally carriers
- Hygienic and sanitisation practices
Clinical signs
- Chlorinated disinfectant (i.e bleach) → Up to 5000 ppm
- Vibrio cholerae → Diarrhoea
- Avoid harvesting molluscs near sewage outlets
- Severe cases profuse watery diarrhoea (enterotoxins)
- Cook seafood completely
- Treatment: quarantine, fluids and antibiotics
- Infected individual should not handle food
- Vibrio parahaemolyticus → Self-limiting diarrhoea , nausea, vomiting, cramps
headache
- Prevent cross-contamination from seafood
- Treatment: supportiv
Vibriosis
- Vibrio vulnificus → Septicaemic, fever, chills, hypotension → Ulcerative lesions
- Facultative anaerobes, motile curved rods
→ Amputation of affected limbs
- Halophilic “salt-lovers” → Seawater with 2-3% NaCl (up to 10%) i.e. Natural
habitat of marine environments
- Treatment: aggressive → 50% fatality not uncommon
Infectious dose
- Human and marine animals can be reservoirs
- High: ~ 10^6 – 10^9 CFU
- Seafood → Faecal reservoir
- Cold-chain good preventative measure
- Temperature: 5 - 43ºC
- Wide pH range: 4.8 -11 (alkalophilic)
Prevention and control
- Heat sensitive → Cooking to 65ºC kills the pathogen
- Good hygiene practices
- Vibrio cholerae → Cholera — Notifiable and Exotic
- Prevent cross-contamination
- Vibrio parahaemolyticus → Enteritis
- Avoid seafood harvesting from known vibriosis ‘hot spot’
- Near sewage
- Vibrio vulnificus → Septicaemic invasive infection = Ulceration and
amputations
- Algal blooms
- Vibrio water check pre-harvesting
Transmission & pathogenesis
- Water treatment and security in aquaculture
- Ingestion of contaminated seafood
- Cold storage of seafood → Prevents growth and proliferation
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AVBS4004 | Food Safety Assessment & Management
Prevention and control
- Cooking seafood
- Travellers should be vaccinated against cholera → India and Zimbabwe
- Temperature to control proliferation and inactivate the diarrhoeagenic toxin
Bacillus cereus
- Refrigerate until ready to serve or cook
- Cooked foods keep above 60ºC
- Food poisoning
- Pasteurisation
- Source
- Cold chain (<5ºC)
- Soil (widely distributed environmental)
- Clean foods at harvest → Eggs , fruits and veggies
- Opportunistic infections in animals
- Hygiene and sanitisation
- Acute mastitis
- Acute mastitis cases not milked for distribution
- Enterotoxins
- Bacteriological monitoring
- Diarrhoea (diarrhoeagenic) and vomiting (emetic)
- Diarrhoeagenic toxin is heat-sensitive
Staphylococcus
- Emetic toxin is heat-stable → Pre-formed and can survive heating at 126ºC
for 90 minutes
- Staphylococcus aureus
- Gram positive cocci, aerobic or facultative anaerobes
- Fried boiled rice → Kept at room temperature for a long period prior to
- Some strains produce heat-resistant enterotoxins
frying
- Food poisoning
- Proliferation of vegetative cells → Emetic toxins produced and survive
heat treatment
- Source: Wide variety of animals, humans (often appear healthy i.e.
Commensally on skin and mucous membranes; Surfaces in contact with skin
(cooking utensiles, milking machines etc..)
- Vomiting within hours of ingestion
- Milk → Cold chain important in preventing proliferation prior to
pasteurisation
- S. aureus can live in high salt (15% NaCl) and sugar (50%)
- Some have acquired drug resistance → MRSA and ‘Superbugs
- Dirty eggs :(
Growth and survival
- Growth: Temperature - 30-37ºC (optimum for toxin production and growth);
Range = 5-55 ºC
- Temperature: Optimum = 37ºC - Range = 4-46ºC
- Diarrhoeagenic toxin inactivated at 56 ºC for 5 minutes
- Growth and toxin production
- Incubation period: Diarrhoea = 8-16 hrs; Vomiting = 30 minutes - 5 hrs
- Heat sensitive - pH = 4.8 – 8
- Viable toxins
- Tolerates nitrites
- Infectious dose: >105 CFU to produce sufficient toxins to cause harm
- Water activity (aw = 0.86 (minimum))
- Most patients recover quickly (24 hours or less) without medical assistant
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AVBS4004 | Food Safety Assessment & Management
Prevention and control
Transmission
- Man primary source in food poisoning
- It takes ~ 106 CFU/unit S. aureus to produce enough toxins to cause gastro
- Mastitis and skin of animals
- Personal hygiene: Washing hands, especially hospitals
- Ingestion of undercooked meats and unpasteurised milk
- Food preparation hygiene
- Pasteurised milk can present a risk due to enterotoxins
- Milk
- Direct and indirect contamination of food sources
- Significant cause of mastitis
- Food preparation and hygiene
- Pasteurisation will not destroy the enterotoxins
- Sneezing on food
Incubation period
- Treat S. aureus mastitis (clinical and sub-clinical) - Withdrawal milk from
mastitic cows
- 1-6 hrs for food poisonings
- Treat mastitic cows
Communicable period
- Milk last or divert milk and disinfect cups
- Carried on animals and man
- On-farm hygiene, milk machine maintenance, workers
- Survival of heat-stabile enterotoxin
- Bacteriological monitoring - <150,000 CFU/ml
- Continuous
- Cold chain → Stop proliferation and toxin formation on food
Clinical signs
- Refrigeration of food <4ºC
- Nausea, vomiting, diarrhoea, cramps
- Don’t leave food at room temperature for too long before cooking
- Headaches, muscle cramping, blood pressure variation
Systemic zoonoses
- Some strains can produce toxins associated with toxic-shock syndrome (TSS)
- Cytokine storm and multi-organ haemorrhage
- TSS and enterotoxins are known as superantigens
- Systemic infection = When an infectious agent or its toxins has spread
throughout the body
- Only the enterotoxins are heat-stabile
- Variety of generalised symptoms
- Need to be toxico-infectious to produce TSS
- Symptoms reflect the spreading nature of the agent, organs invaded,
migration and organ tropisms
Treatment
- Various serious systemic infections of humans transmitted by production
- Food poisonings recover within 2-3 days
animals → Production animals can act as infectious reservoirs
- Mostly associated with ingesting the toxin
Pathogens
- No antibiotic → Don’t want to encourage resistance
Viruses - Arboviral infections › Bacteria - Leptospira interrogans - Coxiella
burnetti - Brucella spp. - Listeria monocytogenes - Bacillus anthracis - Borrelia
burgdorferi - Burkholderia spp. - Mycobacterium spp. - Corynebacterium
- Supportive therapy
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AVBS4004 | Food Safety Assessment & Management
pseudotuberculosis Protozoa - Sarcocystis spp. › Parasitic worms - Fasciola
hepatica - Taenia saginata - Taenia solium - Trichostrongylus spp. › Prions - BSE /
nv CJD
- Resistant to freezing
- Susceptible to drying (needs water !!)
- Heat sensitive
Leptospirosis
- Pasteurisation & cooking
- Invasive pathogen → Through skin and mucous membranes
- Spirochaet
Leptospira interrogans
- Gram negative coiled organisms
- Motile by rapid rotation around long axis and by flexing
- Transmission in humans
- Leptospira interrogans serovars: ~200 serovars
- Ingestion contaminated food, milk or of infected animals (Rare/Raw food/
Kidneys)
- Some are host specific - Some affect animals and humans
- Common zoonotic diseases worldwide
- Direct contact → Splashing of urine during milking - Eye - Skin - Inhaled Flooding
- Occupational hazard → Dairy farmers
- Notifiable
- Human-human rare → sexual and milk
Source
- Spread throughout the body
- Reservoirs
- Clinical signs: Fever, chills, rashes
- Meningitis, anaemia, jaundice and confusion
- Rodents - serovar icterohaemorrhagiea
- Abortion
- Marsupials (zanoni)
- Cows - serovar hardjobovis (hardjo)
- Incubation period - 10-12 days
- Pigs - serovar pomona
- No replication outside the host
- Communicable period → May be excreted for up to 11 months in infected
animals
- Human to human spread is rear
- Infectious dose unknown
- Animals often subclinical/asymptomatic carriers
Treatment and control
Transmission
- Treatment: Antibiotics
- Resides in the kidney → Excreted in urine and birth fluids in animals
- Immunity / Vaccination → Life-long post infection
- Eating contaminated grass
- Serovar specific
- Drinking contaminated water
- Vaccination cows and pigs useful
- Eating infected rodents
- Hygiene:
- Environment → Survive moist room temp. condition
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AVBS4004 | Food Safety Assessment & Management
- Resistant to chemical and physical agents
- Dairy → Disinfectants, PPE (eye wear, cover wounds), Water treatment and
security, Dairy parlor structure, Cows above milkers below, Education of
young dairy farmers
- Survive up to 5 months in the environment (BUT DOES NOT REPLICATE
IN HUMANS OR SOIL)
Q-fever (Coxiella burnetti)
- Incubation period - 19-21 days
- Obligate intracellular bacteria using host ATP
Treatment and control
- Only cultivable in animals, embryonayed eggs or cell culture
- Treatment: Antibiotics
- Humans are usually the only host in which infection leads to disease -
- Prevention and control
- Notifiable
- Protective clothing
- Flu-like syndromes → some are asymptomatic or mild BUT post-Q fever
- Pregnant ewes high risk → shed lots
fatigue syndrome (QFS) - ~ 500 - 700 cases each year in Australia
- Research labs should be kept in containment facilities (PC2)
- Occupational disease → Livestock industry / abattoirs - 75% males
- All bedding, equipment etc. autoclaved before disposal
Source
- Vaccine available for humans
- Cattle, sheep and goats
- Vaccinate animals
- No symptoms
- Antibiotic treatment of animals → Still get shedding
- Sometime abortion seen
- Preventative tick treatment of cattle
- Birth fluid releases large numbers into environment
- HTST pasterurisation
- Domestic animals and ticks
- Chlorinated carcase washing
- Cats and dogs can also secrete in birth fluids
Brucellosis
- Bird and rodent natural reservoirs
- Transmission between natural reservoirs via ticks
- Gram negative short rod, aerobe
Transmission
- Obligate intracellular
- Shed in birth fluid of cattle, sheep and goats
- Heat-senstive → LTLT and HTST pasteurisation
- Found in milk, urine and faeces
- Can survive refrigeration → Up to 6 months at freezing temps in carcases or
tissue (0ºC)
- Aerosol, contaminated soil and direct transmission to humans
- Conjunctival or abrasions in skin
- Sensitive to a wide range of disinfectants and sunlight
- Ingestion is a poor route of transmission
- Sensitive to drying
- Unpasteurised milk → Resulted in change from LTLT → HTST pasteurisation
- B. arbortus → Cattle (horses) – abortion / orchitis
- B. melitensis → Goats and sheep – abortion / orchitis/arthritis
- Organism is heat-tolerant to ~70ºC
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AVBS4004 | Food Safety Assessment & Management
- B. ovis → Sheep – abortion / epididymitis
- No vaccines for humans → Handling wild pig meat, needs HT smoking
- B. suis → Pigs (cattle) – abortion / orchitis / arthritis / spondylitis
Listeriosis
- Sources are uterus and placental discharge and secretions (milk)
- Listeria monocytogenes
- Notifiable
- Small Gram positive rod
Clinical signs
- Intracellular
- Fever and other complications
- Notifiable
- Malta fever (B. melitensis)
- Incubuation period: up to 70 days
- Mediterranean raw goat and sheep milk
- Growth and survival
- Local hypersensitivity → Milkers hand
- Temperature - Grows in the fridge - Psychrotrophic < 4-5ºC
- Incubation period: 1-2 months but varies
- Motile at 22ºC
- Communicable period: Asymptomatic carriers, test and cull, person to
person (rare) , vertical (through milk)
- Survive freezing
- Killed by pasteurisation
- Treatment: Antibiotics for up to 6 weeks
- Resistant to drying
Transmission
- pH range - 4.1 – 9.0
- Direct or indirect
- Salt range: Growth @ 10%; Survival @ 25%
- Contaminated material
- Biofilms on Equipment e..g Slicers
- Uterus and placental fluids
- Can survive 1 yr in environment as a saprophyte (Soil, cool temperature)
- Invade through skin or mucous membranes
- Poorly fermented silage feed - pH > 5.5 → Growth → high concentration →
animal infections/disease = Potent source
- Inhale in dust and aerosols → Abattoir workers
- Ingestion of unpasteurised milk or cheese
Transmission and pathogenesis
- Ingestion of raw or undercooked meats e.g. Wild pig meat in Australia -
- Environment: survives in soil and water
- Infectious dose = 10-100 CFU - GROWS POORLY OR NOT AT ALL ON FOOD
- Intestine of a wide range of animals and humans → Many asymptomatic
Prevention and control
- Common contaminant of raw foods
- Bovine brucellosis - Vaccination (Strain 19) - Milk antibody - Serological
- Clinical signs in animals:
- Ovine and goat brucellosis - Milk antibody - Serological testing for carrier
- Abortions
rams
- Meningitis/CNS disorders
- Porcine brucellosis - Test and slaughter
- Septicaemia
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AVBS4004 | Food Safety Assessment & Management
- Conjunctivitis
- Washing, Cooking, Pasteurisation
- Neonatal and pregnant animals
- CANNOT RELY ON REFRIGERATION OR SALTING → Some strains have been
noted to grow at -1ºC
- Clinical signs in humans:
- Mild flu-like symptoms
- Special care with YOPI
- Abortions or stillbirths
Control and prevention
- Meningitis/CNS disorders
On farm
- esp. in Young, Old, Pregnant, Immunocompromised (YOPI)
- Silage production
- Pathogenesis: Invades via the intestinal epithelium and peyer’s patches Circulation and proliferate in macrophages - Migrates to the CNS, heart,
eyes and foetus
- Poor fermentations allows bad bugs to proliferate
- Starter cultures for silage to control fermentation
- Feed preparation and feed troughs
- Transmission:
- Ingestion of contaminated food
- Clean regularly (it loves decaying vegetative material)
- Faecal/soil contaminates
- Hygiene and sanitation
- Inhalation
Anthrax
- Contact → Minor skin lesions
- Bacillus anthracis
- In utero transfer
- Notifiable disease
- Infectious dose - Not known - Ranges from 102 – 106 ??
- Animal disease
- Communicable period - Shed by asymptomatic animals and humans for
- Sudden death
months
- Internal haemorrhage
- Mothers - Vaginal discharge for one week post partum
- Spores germinate → Exotoxin → Disease
- Treatment - Antibiotics - Early for the most vulnerable - Death may still
result !! - 30% fatality in the elderly
- Carcass is a concentrated source of the bacteria: Amplifiers, Scavengers
Transmission
Transmission
- To humans
- DIFFICULT to eradicate from food processing area → Biofilms; Ubiquitous
nature; Ability to survive and grow in moist, cool location
- Intestinal → incubation period: 3-7 days = vomiting etc. → death
- Pulmonary via inhalation → incubation period: 1-60 days → death
- Bacteriological monitoring useful → Trend analysis + Control point violations
- Cutaneous → Local, black ulcer, fever and headache
or equipment issues
- Treatment – Early multi-antibiotics, chest tube drainage
- Hygiene → Cross-contamination
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AVBS4004 | Food Safety Assessment & Management
Arboviruses
- Source: reservoir hosts → wide range of wildlife, rodents and domestic
animals
- West Nile Virus (WNV)
- Incubation period: 3-21 days
- Australian Arboencephalitis (AAE)
- Clinical signs
- Murray Valley Encephalitis (MVE)
- Acute arthralgia and a rash
- Japanese Encephalitis (JE)
- Headaches, fatigue, muscle soreness
- Kunjin (KUN)
- Nausea, diarrhoea, lymphadenopathy
- Epidemic Polyarthritis (EPA) (Ross River (RR))
- Self-limiting
- Source
- Complete recovery within 2 week to 1 month
- Definitive host: Birds, waterbirds → Asymptomatic
- Residual arthralgia > 1 year
- Pigs amplifiers in JE
- Subclinical infections are common - 60% of infections
- Transmission → Biting mosquitoes, Culex and Aedes spp.
- Treatment: bed rest and pain relief
- People are dead-end hosts (No person - person transmission)
Preventiona and control
Australian Arboencephalitis viruses
- Vector control
- Incubation period - 5-25 days
- Pesticides / Insecticides
- Clinical signs - Nausea, vomiting, fever, dizziness and drowsiness
- Eliminate mosquito breeding sites → Water drainage
- 2-5 days - Meningitis and brain dysfunction
- Fly screens and repellents
- 50% of patient recover rapidly after 10 days
- Avoid bitting times → Dawn and Dusk
- Rest go into stupor, coma and about 25% die
- Dress appropriately
- Survivors have permanent disabilities
- Monitoring of sentinel flocks
- Subclinical infections are thought to be common (99.9%)
- Climate Change → More monsoonal rains and cyclones + temperature
- Treatment: Antimicrobial for secondary infection; Artificial respiratory; No
rising
antiviral available
- Changing weather patterns in populated parts of Australia
- Animals: JE can cause abortion and stillbirth in sows; mostly neurological
illness; high mortality rates; pigs are amplifiers of JE, horses are dead-end
hosts
- Ideal for mosquito migration
- Ideal for emergency of arthropod borne disease in new human
populations
Epidemic Polyarthritis viruses
New variant Creutzfield-Jakob (nv CJD) disease
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AVBS4004 | Food Safety Assessment & Management
- Prion
- Older people
- Modified form of a normal cell surface protein
- Shorter illness
- Prion related protein (PrPr ) → Cause normal cellular prion (PrPC) to convert
to PrPr
- Transmission through iatrogenic infections in hospitals
- Transmitted to human through consumption of meat from BSE affected cattle
which carry this modified protein
- Ingestion of BSE infected meat
nv CJD
- Neurological tissues most risky
- Neurological disorder in animal and man
- Iatrogenic infections in hospitals
- Accumulation of PrPr in nervous tissue (CNS)
- Younger people → Longer illness
- Prion disease (Transmissible spongiform encephalopathy – TSE) → TSE in
other animals not thought to be zoonotic
Prevention and control
Source
- Precautionary measures instituted by the Australian Government
- The country must be assessed by FSANZ and certified as a nil BSE risk to
allow imports
- Cattle in UK, Europe and Nth America → Ingest feed contaminated with
infected animal source
- TGA monitoring and restriction of medicine and medical devices
- Blood and bone meal supplement using BSE-tissue
- Active human and cattle surveillance
- Cattle become ill after ingestion (Mad cow disease) → Ataxia, muscle
tremors and fall down
- Prions highly resistant to heat, cold, chemical or irradiation
- Infected cattle must be incinerated >800°C
- Incubation period 30 months to 8 years in cattle
- Cooking meat does not destroy the prion
- UK banned all cattle > 30 mths of age from being used for human food or
animal feed supplies
- Autoclaving surgical equipment will not destroy the prion
- Infectious after 32 months post infection (experimentally)
- Specific rendering methods on meat and bone meal to destroy prions →
133ºC @ 3 bar for 20 + minutes
- PrPr found in CNS 32 months post BSE brain oral challenge
- Prohibition of feeding offal to cattle
- Incubation period in humans → 15 months to 30 years
- Eat young animals
Pathogenesis and transmission in humans
Avian zoonoses
- Fatal within 2 weeks to 6 months
Classical CJD
- Newcastle Disease Virus
- Mutated PrP
- Mycobacterium avium subsp. avium → Avian tuberculosis
- Sporadic or inherited
- Avian Influenza (H5N1 and H7N9)
- Not zoonotic
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AVBS4004 | Food Safety Assessment & Management
- Chlamydia psittacci → Psittacosis
- Inhalation main route: Environmental or after contact with birds
Psittacosis
- No human cases associated with eating poultry meat
- Chlamydia psittacci
Treatment
- Organism is heat-sensitive
- Obligate intracellular gram negative bacteria
- Humans:
- Source: wild birds are asymptomatic, pet birds (Psittacines) susceptible
- Antibiotics → Lengthy
- Incidence: ubiquitous in Australia
- Alternative for children and women → Side affects of doxycycline
- Associated with use of bird faeces in fertilisers
- Re-infection can occur → Immunity very short-lived
Clinical signs
- Birds:
- Non specific
- Antibiotics for 6-7 weeks → Injections or orally for pets; in water for aviary
populations
- Mild flu → pneumonia
- Low case fatality
- Withholding periods for production birds
- Complications in YOPI: myocarditis etc.
- They also may still carry the pathogens
- 4-15 day incubation period
Prevention and control
- Infectious dose unknown but likely high
- No vaccines
- Communicable when coughing
- Human patients quarantined
- In birds:
- Disinfection of discharge and contaminated articles
- Mostly asymptomatic
- Dead or sick birds: Treated, quarantine or killed
- Ruffled feathers, decrease egg production, diarrhoea
- Disinfection of premises
- Death
- Prophylactic treatment → Aviary not production animals
Transmission
- Biosecurity
- Wild birds and Psittacine birds in commercial aviaries
- Wild birds
- Not in commercial poultry flocks in Australia
- Quarantine new bird
- Turkey flock overseas
- Poultry meat abattoir → Precaution when slaughter and carcas
- Shed in discharge: ocular, nasal and faecal
- Gloves and respirators (gardening)
- Resistant in environmental condition
- Cook meat
- Other animal sources ~ 25% cases not involved direct exposure to birds
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AVBS4004 | Food Safety Assessment & Management
- Slaughter of stock and disinfection of premises
Newcastle disease virus (NDV)
- Vaccine ✓ Used in endemic countries
- Paramyxoviridae
- Hygiene
- ssRNA virus
- All-in/All-out
- 3 strains:
- Regular disinfection of farms
- Lentogenic NDV (lNDV) → Minimal clinical signs
- Biosecurity → Waterfowl Reservoirs
- Mesogenic NDV (mNDV) → Severe clinical signs
- Workers (PPE) → Respirators, gloves, goggles
- Velogenic NDV (vNDV) → Very severe clinical signs
- Virus killed by heat, chemical disinfectants, UV light
- All birds of all ages
- UV exposure of infected eggs (pasteurisation of liquid eggs ✓)
- Humans and other mammals
- Poultry meat should be certified as NDV free for trade purposes
- Respiratory and neurological disease
- Cooking poultry meat well
- Variable severity ~ Age, concurrent disease, stress
Marine phycotoxins
- Case Fatalities up to 80% (vNDV)
- Incubation period = ~5 days
- Marine Phycotoxins
Transmission
- Toxins produced by a small number of marine algae → Algal blooms →
Toxins accumulated in fish → Human food hazards
- Zoonosis
- Marine toxin Syndromes:
- Self-limiting conjunctivitis
- Diarrhoeic Shellfish Poisoning (DSP)
- Skin contact rather than ingestion of meat or eggs from infected feather
dust
- Amnesic Shellfish Poisoning (ASP)
- Transmission → Highly contagious via contact with infectious secretions
- Neurological Shellfish Poisoning (NSP)
- Faeces or aerosols (direct)
- Paralytic Shellfish Poisoning (PSP)
- Feathers
- Ciguatera Fish Poisoning (CFP)
- Fomites (in-direct): Chicken crates, trucks , clothing
- Scombroid
- Vertical (eggs)
Amnesic Shellfish Poisoning (ASP)
- Australia → 3 outbreaks with vNDV → “stamp out” mass culling
- Neurotoxin
Prevention and control
- Fatal
- Control
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- Symptoms : Abdominal pain, vomiting, disorientation and memory loss 15
minutes – 38 hours after ingestion
- Monitor harvesting environment:
- Algal blooms → red (but other colours common)
- Toxin source → Diatom algae
- Optimum 20-25°C, but often seen <15°C
- Shellfish involved → Bivalve molluscs, gastropods, crabs, lobsters and others
- High nitrogen (waste)
- Typically in cooler waters
- Culture algae (>104 cells/L - closure)
Prevention
- Use blue mussel (‘rapid intake/rapid release’)
- Test harvest
- Depuration
- Inspection (cysts of dinoflagellates)
- Monitor harvesting environment → look for temperature 5-15ºC, green algae,
high nitrogen
- Molluscs <0.8 mg/kg
- Testing of harvest (Discard if too much DA toxin)
- Infectious dose ~ 0.1 – 0.3 mg per person, fatal dose 0.5 – 1 mg per person
- Infectious dose (high) ~ 1 mg of DA/kg of body weigh i.e. < 60 mg per
person
Ciguatera Fish Poisoning (CFP)
- Safe concentration for human consumption - <20 mg/kg of edible seafood
- Ciguatoxin produced by a phycotoxic algae
- Dinoflagellate - Gambierdiscus toxicus
Paralytic Shellfish Poisoning (PSP)
- Small herbivorous fish → Fed on by carnivorous fish → accumulation →
public health risk
- PSP toxin → neurotoxins → Tetrahydropurines, about 21 types
- Once confined to coastal and island population, now most common type of
marine food poisoning = global health problem
- STX (saxitoxic) most toxic
- Heat-stable
- Gastrointestinal and neurological symptoms - 30 min - 48 hours incubation
period; Last for weeks to months
- Range of neurological symptoms → slight tingling (pins and needles) or
numbness; and respiratory paralysis and death 2 – 12 hours after ingestion
- Toxin source - Dinoflagellates
Prevention and control
- Shellfish involved:
- Thermostable → cooking does NOT help
- Bivalve molluscs, gastropods, crabs, lobsters and others
- Surveillance → Avoid ciguatoxin “hot spots” (no odour, algal blooms, no
depuration (fish toxic for years) or other visual signs so testing is required)
- Accumulate phycotoxins by filtration and predation
- Cigua-check test kit ($5 per test = expensive)
- Some species can avoid the algae (hard clams and some oysters)
- Avoid consuming large predatory reef fish
- Potentially lethal to predator fish (Mackeral can accumulate PSP)
- Avoid consuming fish organ meat → toxin accumulates in head and ro
Prevention
- Consume small portions and educate restaurants
- Depuration
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12 September 2019
Scombroid
- Histamine toxicity
Epidemiology
- Fish with high levels of histidine in the flesh → Tuna, mackerel, sardine and
anchovy
Descriptive epidemiology → Examine patterns of disease; focus on person,
place, time; use relatively accessible data; used for: assessing disease burden
generating hypotheses
- Histidaine → Histamine
- Source of histamine is bacteria → Bacterial overgrowth due to improper
refrigeration
Analytic epidemiology → Examine causes/risk factors; require more resources;
used for: testing hypotheses
- Histadine is heat-stable
- Symptoms
Risk → is the probability (likelihood) of an event occurring during a specified
time period
- Acute allergic reaction ~ 1 in 100 people have histamine intolerance
Risk factor → is an attribute or exposure that is positively or negatively
associated with the occurrence of disease
- 10-60 minutes after eating
- Flushing (resembling sunburn), itching, headache, diarrhoea and cramps -
Attribute: intrinsic characteristics of host
- Usually resolves in 12 hours, but may cause arrythmias and hypotension
Exposure: extrinsic to host
Prevention
Measuring disease frequency
- Look for signs of tainted fish
- Metallic taste
Aim is to understand impact of disease on population:
- Bubbly appearance
- Burden of disease
- Difference in disease frequency by subgroups (gives clues about potential
risk factors)
- Proper preparation and testing
- Fish need to properly refrigerated (<4°C)
- Study trends in disease over time
- Immediate freezing after caught
Sporadic → disease occurs irregularly and haphazardly
- Best option as same psychrotrophs can convert histidine to histamine
- Cooking, smoking or freezing will not destroy histamine
Endemic/enzootic* → disease is constantly present, at a predictable level
- Test fish flesh
Epidemic/epizootic* → disease is in excess of expected level (similar to
“outbreak”)
- Chemical testing <200 mg/kg
Pandemic/panzootic* → widespread epidemic, involving many countries/
continents
* = in relation to animal populations
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Study design
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Clinical trial
- Gold standard study design
- Incidence in exposed/unexposed can be assessed
- Expensive
- Follow up can be difficult
- Ethical issues
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Cohort study
Case-control study
- Incidence in exposed/unexposed can be assessed
- Can study multiple risk factors (exposures)
- Can study multiple outcomes
- Good for studying rare outcome
- Large numbers of subjects required to study rare diseases
- Relatively inexpensive and quick (no follow-up)
- Take a long time
- Incidence in exposed/unexposed cannot be measured
- Follow up can be difficult
- Difficult to select appropriate controls (prone to bias)
- Expensive (retrospective = cheaper)
- Exposure assessment based on recall or records
- Can be prospective or retrospective
Cross-sectional
- Exposure and outcome data collected simultaneously
- Often conducted via surveys
- Relatively inexpensive and quick to conduct
- Useful when burden of disease is main measure of interest (can estimate
disease prevalence)
- Can study multiple risk factors (exposures)
- Unsuitable for study of rare diseases
- Hard to describe temporal sequence (chicken or the egg?)
- Incidence in exposed/unexposed cannot be measured
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Measures of association
Relative risk
- Exposed group was X times more likely to develop disease compared to the
unexposed group; OR
- The risk of disease was X times higher in the exposed group compared to the
unexposed group
- Statistically significant if 95% CI does not include 1.0/p<0.05
Judging causality = Bradford-Hill’s criteria
- Association is strong (RR of 3+)
- Exposure precedes outcome (temporal relationship)
- Dose-response between exposure and outcome
- Cessation of exposure → ↓ frequency of outcome
- Consistency between studies, subgroups, populations
- Biological plausibility (current knowledge supports)
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Odds ratio
- Works even for rare diseases (morbidity <10%)
Case-control (when incidence can’t be measured)
- Cases were X times more likely to have been exposed compared to controls
Bias
Possible explanations for observed associations
- Causal association (red meat causes colorectal cancer)
- Bias (systematic error in data collection/analysis)
- E.g. people who eat red meat more likely to be smokers, advertise study on
Cohort study (when incidence can be measured)
red meat and cancer
- Exposed group was X times more likely to develop disease compared to
unexposed group
- Chance (sampling error, usu. set at 5%)
- By chance, we sampled more people who eat red meat and developed
cancer than actually occurs in the population
Bias → Any systematic error in the design, conduct or analysis of a study that
results in the mistaken estimate of an exposures effect on the risk of disease.
Biased studies are said to be “internally invalid”.
Selection bias
- Occurs when the composition of the study population differs with respect to
the distribution of exposure/outcome in the source population
- Non-response bias
- Selective entry/survival bias
- Loss to follow up bias (cohort/clinical trial only)
- Be aware of:
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- What was the response rate like?
Controlling confounding effects
- Who responded (vs source population)?
- Design phase:
- Was loss to follow up even among groups?
- Randomization – balances groups (in theory)
- Careful not to recruit on basis of having exposure and outcome (e.g. blind
recruiter to study hypothesis)
- Restricting – only 1 level of factor enrolled
- Matching – balances groups
- Cohort/clinical trial: identify reason for leaving
- Analysis:
Information bias
- Stratified analysis – results reported separately
- Logistic regression – “adjusted for”, “controlling for”
- Occurs when subjects are incorrectly classified with respect to their exposure/
outcome status. Includes both misclassification bias (categorical data),
measurement error (continuous data)
- Non-differential (random) misclassification of outcome/exposure - generally
biases results toward null
- Differential (non-random) misclassification of outcome/exposure - biases
results in either direction
- Be aware of:
- Did they use the best possible (validated) instrument/tool/test to measure
exposure/outcome?
- Did they use objective measure/avoid self report/back up self-report with
other information?
- Was the person who measured the outcome/exposure blinded to the
exposure/outcome?
Confounding bias
- Occurs when the observed association between the exposure and outcome
of interest is actually due to another factor or factors
- Confounders are:
- Risk factors for the outcome
- Associated with the exposure
- Not in the causal chain
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- Sen = TP/TP+FN
Diagnostic tests
Specificity
Choice of test
- ability of test to only identify one chemical compound (vs cross-react with
multiple compounds)
- Depends on consequences (harm, cost) of FN and FP
- Sometimes desire high sensitivity i.e. avoids FN, FP ok
- Fraction of animals without disease who test negative
- Ex: rabies, exotic disease (consequence of FN very high)
- Spec = TN/FP+TN
- Usu. followed up with more specific test to confirm result
- Sometimes desire high specificity i.e. avoids FP, FN ok
- Ex: freedom assurance programs (consequence of FP very high)
Sensitivity
- lowest concentration of chemical compound that test can detect
- fraction of animals with disease who test positive
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Positive predictive value
Relationship between disease prevalence and predictive value
- Given a positive test, the likelihood that the animal actually has the disease →
i.e. fraction of animals with positive test who have the disease
Negative predictive value
- Given a negative test result, the likelihood that the animal doesn’t have the
disease → i.e. fraction of those with negative test who don’t have the disease
- ↑ sensitivity → ↑ negative predictive value = Fewer FN
- ↑ specificity → ↑ positive predictive value = Fewer FP
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Monitoring and surveillance
- Meet international and product certification requirements
Surveillance → systematic ongoing collection, collation and analysis of
information related to animal health and the timely dissemination of
information so that action can be taken
Types of surveillance
- Detect outbreaks of disease (early detection)
- Disease Focus
- Targeted (Specific) surveillance (a single disease)
Monitoring → intermittent performance and analysis of routine measurements
- General surveillance (all diseases)
and observations, aimed at detecting changes in the environment or health
status of a population
- Approach to data collection
- Go out and look for information (investigator initiated) – Active surveillance
- Wait for information to come to us (observer initiated) – Passive surveillance
Passive surveillance
- Provider-initiated
- Physicians/labs send case reports to health
department
- Reporting mandated at the state level
- Tend to be on-going
- Tend to under-estimate disease burden
- E.g. National Notifiable Disease Surveillance
System
Active surveillance
- Health department-initiated
Surveillance
- Active case finding and training of healthcare
providers
- Gather info → Analyse → Interpret → Act → Assess → Repeat
- Often focus on specific diseases/outcomes
- Inform decisions on disease control priorities
- May be ongoing or limited in time
- Animal health
- Tend to produce better estimates
- Human health – foodborne and zoonotic pathogens
- E.g. Foodborne Diseases Active Surveillance Network
- Evaluate impact of disease control programs
- Provide evidence of freedom from disease
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Syndromic surveillance
19 September 2019
- Newer type of surveillance activity
Chemical hazards
- Uses data that pre-dates clinical diagnosis → e.g. over the counter
medications (anti-diarrheal), school/work absences, hospital admissions
(gastroenteritis)
National Residue Survey (NRS)
- Early detection of outbreaks/emerging diseases
- NRS established in early 1960’s following DDT residues found in Australian
Outbreak investigation
beef exports to the US.
- Mandatory requirement for animal products to support export certification
under Export Control Act 1982.
Attack rate → term used for incidence in outbreak settings • Index case: first
case (e.g. exposed to food item)
- Approximately 9,500 animal product samples are collected annually for
analysis of agricultural and veterinary chemicals (registered & unregistered) in
addition to environmental contaminants (e.g. heavy metals).
Secondary cases → cases that become infected following contact with index
case/s or other secondary cases
- Approximately 7,100 plant product samples are collected annually for
analysis of agricultural chemicals (registered & unregistered) in addition to
environmental contaminants.
Point source epidemic → everyone gets exposed from common source over
short period (e.g. picnic)
Continuous source epidemic → exposure occurs over a prolonged period (e.g.
supermarket product)
- Operates under a Quality Assurance Program: ISO 9001:2015.
Propagating epidemic → exposure results from human to human spread
Role of the NRS
- Manages national residue monitoring programs for participating animal &
plant industries.
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- Provides an independent audit of residue integrity.
- Horticulture including almond, apple, citrus, macadamia nuts, onion & pears.
- Residue testing results support:
NRS programs responsibilities
- export certification of animal & plant commodities
1. Program development, including consultation with industry & State
governments.
- domestic quality assurance programs
- Provides accumulated residue testing data to:
- support ongoing or new market access
2. National collection of samples via departmental officers and approved
sample collectors.
- demonstrate long term integrity of Australian exports
3. Sample transportation and management of chain of custody.
4. Analysis of samples – oversight of seven contract laboratories.
Scope of the NRS
5. Reporting of results to industry and markets.
- NRS Administration Act 1992
6. Advice to State Authorities for traceback investigation of violative residues.
- Contaminant: a substance will be a contaminant if it is an impurity which gives
Chemical screen development
consumers health, safety or cleanliness concerns.
- Includes:
Chemical screens are developed based on assessment of:
- residues (from use of agricultural & veterinary medicines)
1. International market access requirements.
- environmental contaminants (Hg, Cd, Pb)
2. Previous results & product coverage.
- mycotoxins (aflatoxin, patulin, zearalenone, deoxynivalenol)
3. Availability of suitable sampling & analytical methods.
- GMOs
4. Likelihood of residues occurring in the product.
- micro-organisms
5. Agricultural & veterinary chemicals registered for use.
Products covered by the NRS
6. Maximum Residue Limits (MRLs) in destination markets.
Animal
7. Public health perception of the chemical by international and domestic
regulators.
- Major animal species: cattle, sheep and pigs.
8. Advice from Technical Panel (NRS, Department, APVMA & State Authorities).
- Minor animal species: camel, deer, emu, goat, horse, kangaroo, ostrich,
Matrix selection
poultry, game deer, donkey, wild boar, eggs, honey, aquaculture fish and
wild-caught seafood.
- Cereal grains: wheat, barley, maize, oat, sorghum & triticale.
The material usually selected for analysis is the one that is expected to contain
the highest concentration of a residue. The material may be inedible, and does
not necessarily represent the part most likely to be eaten.
- Pulses: beans, peas, lentil, lupins & vetch
- Fat - pesticides
- Oilseeds: canola, safflower, linseed & soybean
- Kidney - antibiotics
Plant
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National Livestock Identification Systems (NLIS)
- Liver - metals
- Urine or faeces - hormonal growth promotants (HGPs)
- Cattle - individual animal life history movements recorded via electronic
Sample collection and online portal
tags (sheep/goats in VIC from 1 July 2017).
- Sheep/goats – NLIS/RFID (VIC only) & mob-based movements. Horses –
collars (wild brumbies excluded).
- The NRS operates an online portal which provides an interface with the
sample collector and the NRS for all sample collections.
- Pigs – tattoos.
- Sample requests are generated based on establishment slaughter
throughput.
- Extended residue program (ERP) statuses → e.g. T3V (OC contamination) set
in National Livestock Identification (NLIS) database allow potentially
contaminated stock to be tested at slaughter when device or PIC-based
status flags are set.
- Samples are collected in tamper-proof satchels by departmental on-plant
veterinary (OPV) officers at export establishments or approved sample
collectors at domestic establishments.
Laboratories
- Collected samples are sent by overnight courier to the Central Receival and
Dispatch (CRAD) for batching to laboratories for analysis.
- NRS analytical programs are undertaken by contract labs.
- Chain of custody is verifiable at all times via the IMS
- Small laboratory community.
Sample traceability
- Not based on reference laboratories.
- No distinction between government/private labs.
- Do not prescribe “official” methods.
- Labs procured through open, competitive tender (>1993) based on:
1. demonstrated performance in NRS proficiency testing (PT → send known
sample to multiple labs to determine their proficiency)
2. NATA accreditation (National Association of Testing Authorities)
3. value for money
- Contracts awarded for specific analyte/matrix combinations
Australian residue and contamination standards
- Australian Pesticides and Veterinary Medicines Authority
- Sets Maximum Residue Limits (MRLs) for approved uses of agricultural and
veterinary chemicals.
- Standards only apply in Australia.
Property Identification Code (PIC) or animal tattoo, collar and or RFID is
essential for tracing an individual slaughtered animal.
- Food Standards Australia New Zealand
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- Incorporates standards set by the APVMA in addition to setting standards
for contaminants.
- Audits are performed against five criteria established in the Livestock
Production Assurance (LPA) scheme including:
- Import tolerances to allow for approved uses in importing countries not
covered by the Food Standards Code.
- animal transportation
- Some standards apply jointly in New Zealand.
- animal treatments
- traceability
Federal Register of Legislation https://www.legislation.gov.au
- stock food
Traceback investigation of violative residues
- property risk assessments
- In 2019-20 >1,000 audits are scheduled to be undertaken Australia-wide on
cattle, sheep and goat properties.
Upon confirmed violative result…
1. NRS requests State Authority e.g. Dep of Ag to undertake an on-farm
Abattoir preparation
investigation to identify cause.
2. State Authority investigates & provides education to producer to prevent
recurrence and/or regulatory action if required e.g. quarantine.
Antimicrobial resistance and
OneHealth
3. NRS reports outcomes to Australian Pesticides and Veterinary Medicines
Authority (APVMA) where relevant.
4. Livestock Production Assurance (LPA) audit requested after completion of
traceback.
Microbial hazards and
diagnostics in food safety
5. Results >1/2 Maximum Residue Limits (MRL) are referred to State for
“information only”. In some cases the State will investigate e.g. Pb.
Targeted animal testing programs
‘Gate-to-plate’ disease control
programs
- Targeted Antibacterial Residue Testing (TART) for cattle, sheep, pigs, goats
and horses.
- National Organochlorine Residue Management (NORM)
- National Antibacterial Residue Minimisation (NARM) → bobby calves
He
- Ad hoc e.g. cotton trash CTP status
- Requirements are set out in meat notices and or departmental guidelines
Hi
Livestock program assurance program
Mini subtitle
- National on farm audit program is conducted to assist in the verification of
on-farm practices e.g. vet treatments.
Ugh
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