BIOLOGICAL HAZARDS
…health hazards
associated with
exposure to
biological agents
Definitions
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Biohazard – organisms or products of
organisms that present a risk to humans
Organism – a living thing, such as a germ,
plant, animal, or human that may consist of
several parts, with each part specializing in a
particular function
Microorganism – a minute organism, such as
microbes, bacteria, cocci, viruses, molds, etc.
Development of Biosafety
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Army at Fort Detrick – Frederick, Maryland
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1941 – Chemical Warfare Services
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Researching biological warfare agents
American Society of Microbiology served as advisors to CWS
1970’s – Recombinant DNA technology
1980’s - Appearance of HIV
1991 – OSHA’s Bloodborne Pathogens Program (29
CFR 1910.1030)
RECENT INCREASED AWARENESS
OF BIOHAZARDS
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Newest subset of focus
Contributing to awareness
Legionnaires’ disease
AIDS epidemic
rDNA technology
anthrax
Specialists exist but their
numbers are small
S/H/E professionals have
become involved
Occupational hazards…
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Healthcare
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Research facilities
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Bites, scratches, parasites, diseases, allergens
Biotechnology facilities
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Workers may be exposed to infectious microorganisms that are associated with the plants or animals
Food and grain handlers, farmers, laborers – may be exposed to parasitic diseases
Processors who handle animal products – may acquire bacterial skin diseases from working with contaminated hides, infected with
contaminated fish, meat or poultry, Bacterial infections from exposure to feces from infected turkeys, geese, ducks, etc.
Animal facilities/Veterinary practices
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Q fever, hepatitis, typhoid fever, tuberculosis, dermatomycosis
Percutaneous inoculation (needles/syringes, cuts or abrasions from contaminated items, and animal bites/scratches); inhalation of aerosols,
contact between mucous membranes and contaminated material (hands and surfaces), and ingestion
Agriculture
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Hepatitis, tuberculosis, infections
Infections categorized as:
Community acquired – transmitted to either patients or workers
Occupationally acquired – resulting from worker exposure
Nosocomial – hospital-acquired infections of patients
Genetically engineered bacteria, fungi, plant and animal cells for development of products
Miscellaneous occupations
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Workers maintaining water systems (legionella); pet shops; zoos; wood-processing facilities (fungi); sewage workers (bacteria, virus, parasites);
forestry workers (Rocky Mountain spotted fever, lyme disease, viruses and bacteria from ticks, fungi); child care workers (bacteria (shingles),
viruses (measles, chickenpox); public safety workers (bloodborne pathogens, viral respiratory diseases (influenza).
Biohazards are…
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Inherently different
from chemicals,
physical agents,
carcinogens, etc.
BUT, recognition,
evaluation and control
still can be applied
Biological materials typically…..
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Have no threshold level of exposure, i.e., dose and
response relationship
Are ubiquitous in the environment so the idea of
“permissible exposure limits” is inappropriate
Are affected by biological competition rather than
behaving in an additive or synergistic way
Interact with the host and its environment to produce
the adverse effects
For illness to occur…..
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The agent must be pathogenic.
There must be a reservoir of sufficient
number.
The agent must escape the reservoir.
The organism must be able to move
through the environment.
There must be a portal of entry for the host.
The host must be susceptible to the agent.
Factors affecting infection and
exposure
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Modes of transmission
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Routes of entry
Infectious dose (infective dose)
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Number of microorganism
Viability and virulence of agent
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Contact (direct/indirect, zoonotic); vector-borne, airborne
Viability - Ability to replicate
Virulence – Ability to cause disease
Host susceptibility
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Skin disorders, immune system, vaccination allergy, infection
of fetus, work practices
Classification of Biohazards
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Microorganisms
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Examples: viruses, bacteria,
fungi, protozoa, algae
Reactions: infection, exposure,
allergic reactions
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Arthropods
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Examples: crustaceans,
arachnids, insects
Reactions: skin inflammation,
allergic reactions, systemic
intoxication, transmission of
infectious agents
Allergens
Protein Allergens
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Examples: from higher plants
Reactions: Dermatitis, rhinitis,
asthma
Examples: vertebrate animals
(urine, feces, hair, saliva, dander)
Reactions: allergic reactions
Parasites
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Examples: ticks, hookworms,
pinworms
Reactions: skin reaction,
inflammatory response, allergic
reaction
Some common biological agents
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Bacteria
Viruses
Rickettsiae
Fungi
Parasites
BACTERIA
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Simple, one-celled
organisms
Cocci, bacilli, spirilla
Some are pathogenic,
some are harmless, some
are even useful
Broken skin is particularly
vulnerable
“Food poisoning” in mass
VIRUSES
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Smallest known
organisms
Living (?) non-cellular
entities
Are “obligate parasites” &
cannot survive without
living cells
Common occupational
exposures to animal virus,
poxvirus & arbovirus
RICKETTSIAE
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Bacteria-like but smaller
Are obligate parasites
Transmitted to humans
via bloodsucking
arthropods (fleas, ticks
& lice) or through the air
Responsible for typhus
and Rocky Mountain
spotted fever
FUNGI
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Broadest spectrum
among biological agents
Are either parasitic or
saprophytic
Hypersensitivity due to
inhaled fungal antigens
Fungal disease is rare
but includes ringworm &
athlete’s foot
PARASITES
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Parasitic to plants or
animals
Diseases include
malaria and other
blood and GI infections
Dermatitis and other
skin-related ailments
due to mites and
chiggers, etc.
Legionnaires’ Disease
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Caused by legionella pneumophila, a bacterium
Presence possible if moisture, elevated temperature,
oxygen and nourishment available
Clearly can be transmitted through air and perhaps
other ways
Symptoms resemble a form of pneumonia and can be
treated accordingly
About 15% of known cases have been fatal
Tuberculosis (TB)
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Bacterial disease caused by Mycobacterium
tuberculosis
Some populations are at greater risk
Transmitted by inhalation of infectious droplet nuclei
suspended in air
Symptoms
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Early on: fatigue, fever, weight loss
Later: Hoarseness, cough, hemoptysis (blood-tinged sputum),
lesions in respiratory tract
Acquired Immune Deficiency
Syndrome (AIDS)
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Caused by HIV, a virus
Transmitted via sexual contact, sharing of
needles and transfused blood
Symptoms include tiredness, fever, night
sweats, weight loss
No single test as diagnosis
Treatment (at present) cannot cure or restore
the immune system
Anthrax
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Caused by spore-forming
bacterium Bacillus
anthracis
Found in imported animal
products
Types of anthrax
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Cutaneous anthrax
Inhalational anthrax
Gastrointestinal anthrax
Cutaneous Anthrax
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Most common naturally
occurring infection
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Incubation period of 1-12 days
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Symptoms:
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small, raised bump
ulcer with black center
fever, headache, malaise
Inhalational Anthrax
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Most lethal form
Incubation period of 1-7 and
possible 60 days
Symptoms:
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sore throat, fever, muscles aches
respiratory failure and shock
Fatality rate of approximately 75%
Gastrointestinal Anthrax
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Follows consumption of raw or
undercooked meat
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Incubation period of 1-7days
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Symptoms:
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sore throat, fever
loss of appetite
nausea & vomiting
Fatality rate between 25%-60%
SUMMARY
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A tremendous variety of biological materials
exists as potential exposure agents.
Effects of bio-hazardous agents are subtle
and slow in developing.
There is increasing concern about, and
interest in, biological materials.
Bottom-line: biohazards are (and must be)
treated with extraordinary caution.