By : Dr ASLANI
OCCUPATIONAL MEDICINE SPECIALIST
Contents:
 Definition of biologic agent
Types
Spreading
Definition of occupational infection
TB
HBV
HCV
HIV
Zoonoses
Controlling the risks
Definition of biologic agent:
 Biological agents are living organisms or
products of living organisms.,
which may cause infection, allergy, toxicity
or otherwise create a hazard to human
health.’
Types:
They include:
 bacteria
 viruses
 fungi (yeasts and moulds)
 parasites
 plants
Occupations and workplaces where people
may come into contact with biological
hazards
 Medical staff, cleaning staff and laboratory
technicians in the medical profession;
 Healthcare services;
 Cleaning services
 Agriculture, fishery, veterinary services,
BIOLOGICAL OCCUPATIONAL HAZARDS
 infectious
 allergic
 toxic
Markku Seuri, FIOH, 2004
9
 = occup. biohazards
SPREADING
 by inhalation
 by ingestion (from hand to mouth)
 by sharps injuries
 by blood or other body fluid contact
 by bites
 Work-related infection has been reported in the
literature as the third leading cause of occupational
disease.
 Healthcare workers (HCWs) who are most often at
the frontline of outbreaks of emerging agents and
infectious patients are more at risk.
Definition of occupational infection
 Work-related infectious disease is referred
to as disease that is caused or aggravated by
occupational exposure to biological agents
including bacteria, fungi, viruses and
parasites (helminths, protozoa) through
human, animal and/or environmental
contact.
Occupational infection can occur
following:
 contact with infected persons, as in the case of
health care workers.
 with infected animal or human tissue, secretions,
or excretions, as in laboratory workers.
 with infected animals, as in agriculture.
 ………………………….
Occupational illness through contact with human
Type of
contact
Agents
Prevention
Percutaneous
inoculation
Hepatitis B, C
Gloves, needle stick
prevention
Air born transmission
TB, VZV,SARS, measles
Respiratory isolation,
air filtration(TB)
Respiratory droplet
SARS, rubella, influenza, mycoplasma, Respiratory isolation,
diphteria, etc
respiratory droplet
precautions
Fecal- oral
Shigella, vibrio, clostridium difficiel, E
coli, etc
Hand washing, gloves
Direct contact
HSV, VZV, SARS
Gloves, protective
clothing
TUBERCLOSIS
tuberculosis
 ‫مایکوباکتریوم توبرکلوزیز‬:‫عامل‬
 Incubation Period :(+PPD)4-12W
 The risk of development of clinical disease following
infection is higher in
-‫سوء تغذیه‬
-‫نقص ایمنی‬
-(‫ژنتیک‬HLA Bw15 )
- ‫سن(کودکی و‬16-21 )‫سال‬
- ‫ کارسینوم‬،‫ لنفوم‬،‫ لوسمی‬،‫بیماری ها(سیلیکوز‬UpperGI‫دیابت‬،(
tuberculosis

HIGH RISK WORKS:
 Staffs of
laboratories and necropsy rooms
 health care settings (especially hospitals,
long-term care facilities, and dialysis centers)
 substance abuse treatment centers
tuberculosis

Tubercle bacilli may be present in :
gastric fluid
cerebrospinal fluid
urine
sputum
tuberculosis

Transmition:
coughing
sneezing
talking by expelling small infectious droplets
that may remain suspended in the air for
several hours and then inhaled by susceptible
persons
tuberculosis

PPD>=5mm:
 close contacts of
infectious patients
 immunosuppressed
 persons with known or suspected human
immunodeficiency infection (HIV)
tuberculosis

PPD>=10mm:
 high-prevalence
(> 5%),
 high-risk occupational groups (above)
 high-risk groups such as
-immigrants from high prevalence areas
-alcoholics,
-intravenous drug users, and
-those with other disease states mentioned above
tuberculosis

PPD>=15mm:
 persons
with no risk factors in areas of low
prevalence
tuberculosis

PPD:Neg
 measles
 Hodgkin
disease
 sarcoidosis
 immunosuppressive states
tuberculosis
 Occupational candidates for periodic PPD
testing include
 those having contact with suspected or known
infected patients,
 persons working with potentially infected cattle
(veterinarians,……)
 all others working in the higher-risk environments
mentioned above.
Hepatitis B Virus (HBV)
Individuals at occupational risk
 Hepatitis B vaccination is recommended for the
following groups who are considered at increased
risk:
healthcare workers
laboratory staff
other occupational risk groups:
-morticians and embalmers
-prison service staff.
 The prevalence of HBV infection among health care
personnel was 10 times higher than the general population
 Blood contains the highest titers of virus in infected
individuals
 with lower levels in various other body fluids,
 cerebrospinal,
 synovial,
 pleural,
 peritoneal,
 Pericardial,
 amniotic fluids,
 semen and vaginal secretions.
 Viral titers in
 urine,
feces,
tears
Saliva
are low enough that these are not felt to be routes of
transmission
 The risk for transmission of HBV through
needlestick injuries is approximately 30%.
 HBV can remain viable for at least 1 month on dried
surfaces at room temperature.
-This poses additional opportunities to acquire
occupational HBV infections when individuals with
 open cuts
or
 abraded skin or mucous membranes contact
contaminated surfaces
Prescreening serologic testing
 The current recommendations
 check for surface antibodies 4 weeks to 6 months
following the primary series.
 If the person tests negative for antibodies,
--- three additional doses (for a total of six doses) will
induce antibodies in 30–50% of nonresponders.
 Those who do not develop
antibodies after six total doses
should consider changing positions
at work not involving blood or blood
products.
Hepatitis C Virus (HCV)
Occupational Exposure
 It has been well-documented that transmission
of hepatitis C in a health care situation can occur.
 The current estimate for transmission of HCV
following a needlestick injury from a positive
carrier of HCV is approximately 1.8%.
 Transmission following mucous membrane
exposure is rare.
Following exposures to known
HCV-positive blood or blood
products
 HCV RNA testing is often
considered 2–4 weeks after
exposure
Following exposures to Unknown
Source
 HCV Ab testing is often considered
6–8 weeks after exposure
Human Immunodeficiency
Virus (HIV)
HIV transmission
 occurs via blood and sexual contact.
 Fortunately, occupationally acquired
infection has been a relatively
infrequent (albeit serious)
occurrence.
body fluids considered higher risk for HIV
transmission
 Blood
 semen and vaginal secretions
 cerebrospinal
 synovial
 pleural
 peritoneal
 pericardial
 amniotic fluids
The established rate of transmission
following a positive HIV exposure from a
needlestick injury
 is approximately 0.3%,
making it approximately 10-fold less
transmissible as HCV
and 100-fold less transmissible as HBV.
postexposure TEST
Baseline testing for preexisting
infection at the time of the exposure
follow-up testing at 6 weeks and 3 and
6 months.
zoonoses
 Zoonoses are defined as any disease and/or
infection that is naturally transmissible from
vertebrate animals to humans.
 Occupations involving contact with infected
animals and/or their infected secretions or tissues
or contact can result in workrelated zoonotic
disease.
Zoonoses(occupation at risk)






veterinary medicine
farm workers
zoo keepers
meat processing plant workers and butchers
leather industries
pet shop workers
zoonoses
 Zoonoses involve different types of agents:
 bacteria (eg, salmonellosis and
campylobacteriosis),
parasites (eg, cysticercosis/taeniasis),
Rickettsia (eg, Q-fever),
viruses (eg,rabies and avian influenza),
Controlling the risks
 eliminating risks:
eg by substituting a hazardous biological agent
with something less/non-hazardous:
 eg using a non-toxigenic strain of a biological
agent when carrying out laboratory quality control
(QC) tests;
Controlling the risks
Engineering controls such as improvement of
- ventilation,
-partial isolation of the contamination source,
-installationof negative pressure and separate
ventilation and airconditioning system (e.g. in
medical wards for infectiousdiseases)
-the use of ultraviolet lamps can help contain the
spreadof contaminants.
Controlling the risks
 If the contact with biological hazards cannot be
prevented,
the employees must use personal protective equipment
and adhere strictly to the practice of personal
hygiene.
Controlling the risks