Biological Agents

A description of Biological Agents that could affect people in the workplace if Health and Safety protocols are not followed.

1. Biological Agents

2. Zoonoses
Zoonoses are animal infections which may be
transmitted to people in the course of their work.
Common examples include:
Brucellosis
Q Fever
Orf
Psittacosis
Anthrax
Glanders

3. Brucellosis
Caused by the bacterium Brucella abortus, which may infect
people handling cattle or pigs or their carcasses in abattoirs
Not very severe but involves loss of appetite, headache,
insomnia and slight fever
In the UK a policy of eradication has been pursued since the
60’s by destroying any infected cattle

4. Q Fever
Known to occur in farm workers, abattoir workers and
veterinary surgeons
The causative agent, Coxiela burnetii, has been found
in cows and sheep
Not as serious as Brucellosis and takes the form of
cold or `flu-like symptoms

5. Orf
A contagious pustular dermatitis of viral origin,
mainly affecting farm workers, shepherds, sheep
shearers, butchers and abattoir workers
Lesion enlarges and often becomes ulcerated,
exuding fluid and pus
Complete recovery occurs in about 3 weeks

6. Psittacosis
A virus-like bacterium of poultry, game and other birds
Can be fatal to man if untreated
Illness sets in suddenly after an incubation period of 2 to
3 weeks with fever, headache and lethargy
Pulmonary symptoms follow in a few days and mortality
may be as high as 20%, particularly in the elderly

7. Anthrax
An acute infectious disease of farm animals caused by a bacterium
Transmitted to man by contact with infected hair, hides, excrement or
products such as bonemeal
Fatal without treatment
Initial lesion rapidly becomes ulcerated
Treatment is by penicillin
Inhaling the pathogen causes pulmonary anthrax which is usually fatal in 3
or 4 days

8. Glanders
An infectious disease of horses, donkeys and mules caused
by the pathogen Pseudomonas mallei
Transmitted to humans by nasal or mouth secretions from the
infected animal
Abscesses appear on hands, arms or face
Lasts up to 4 months but is treatable with modern antibiotics

9. Zoonose Control Strategies
Most common route of entry is via the skin, by way of
open cuts, sores or abrasions which provide direct entry
to bloodstream
Other routes include inhalation of contaminated dusts,
contact with conjunctiva of eyes, direct injection by cuts
from infected animals or animal bites, and direct
ingestion via hands

10. Zoonose Control Strategies
First stage of control strategy is to assess those people
at risk
Factors to consider include:
work being carried out
susceptibility to infection of the workers
how infections might occur
how likely exposure to infection is

11. Zoonose Control Strategies
First priority for preventing occupational exposure to
zoonoses is to eliminate the infections from the animal
stock, usually by protecting exposed animals through
immunisation and improvement of their environment
Workers should be protected by suitable
environmental hygiene controls and wearing protective
clothing including hand, arm, foot and leg protection

12. Zoonose Control Strategies
Where animal products likely to emit infected dust are handled
(e.g. wool, skin, hides, pelts), LEV and possibly RPE should be
provided to prevent airborne infection
Specific immunisation of workers may be necessary
Clean & hygienic animal living conditions and disinfection of
stalls will also ensure better hygiene in factory premises and
will reduce probability of infection

13. Zoonose Control Strategies
Automation to reduce human contact and
enclosure of aerosol-producing activities will
reduce exposure to infection
Finally, medical checks, training and information,
procedures, instruction and records will give added
protection to workers

14. Legionnaires Disease
Caused by the bacterium Legionella pneumophilia
A type of pneumonia affecting the lungs and other organs
A number of conditions have been found to affect rate of growth:
Water temp. in the range of 24-45
o
C. It does not survive about 60
o
C.
Organisms may remain dormant in cool water
Sediment, sludge, scale and organic material in water systems can act
as a source of nutrients, as can organisms such as algae, amoebae
and other bacteria
Incorporation of Legionella in slime on surfaces can protect the
organisms from biocides

15. Legionnaires Disease
Infection caused by inhaling airborne droplets or particles
containing Legionella, which are small enough to pass deep into
the lungs and be deposited in the alveoli
People at greatest risk include smokers, alcoholics and patients
with cancer, chronic respiratory or kidney disease
Initial symptoms include high fever, chills, headache and muscle
pain. A dry cough soon develops and most patients suffer
difficulty with breathing

16. Legionnaires Disease
Water systems potentially at risk include:
Cooling towers
Evaporative condensers
Hot/cold water services where occupants are susceptible, I.e. health
care premises
Humidifiers and air washers creating a spray of water droplets above
20
o
C
Spa baths & pools

17. Legionnaires Disease
Employers should manage the risk of Legionella by:
Identifying and assessing sources of risk, taking into account potential for
drop formation, water temperature, exposure probability and adequacy of
control
Implementing and managing precautions and keeping records of the
precautions
Particular attention should be paid to populations which contain a high
proportion of susceptible people (hospitals or nursing homes) and situations
where there is a large number of such people at risk

18. Legionnaires Disease
Main aim of control measures is to avoid conditions where Legionella can
proliferate and to avoid creating sprays or aerosols
Growth of Legionella can be inhibited by:
Avoiding water temperatures between 20-45
o
C
Avoiding water stagnation & slimes
Avoiding use of materials which provide nutrient for the organisms
Keeping the system clean and preventing a build-up of sediments
Using appropriate water treatment chemicals

19. Sick Building Syndrome
Occupants suffer from measurably higher incidence of illness
than would be expected, for no readily identifiable reason
Symptoms may include ear, nose and throat irritation; skin
rashes; lethargy; headaches; respiratory infections and nausea
Occurs predominantly in air conditioned buildings
Victims tend to be in low status repetitive jobs and have little or
no control over their working environment

20. Sick Building Syndrome
Symptoms are more frequent in offices with large numbers of
employees, and are also reported with greater frequency in the
afternoons than in the mornings
Cause is likely to be due to a number of factors, some of which
may be biological, others not
Airborne contaminants may cause SBS symptoms through
several mechanisms, including toxicity, irritations, infection and
allergy

21. Sick Building Syndrome
Other factors include inadequate ventilation and low humidity
Several “temporarily sick buildings” have been “cured” by
increasing ventilation, amongst other measures
Overall conclusion is that SBS is a complex phenomenon with a
number of causes, possibly influenced by the victims reaction
and attitude to the working environment

22. Leptospirosis - Weil’s Disease
An infectious jaundice with symptoms of fever, jaundice, liver
enlargement, haemorrhages and feverish relapses
Causative organism is a spirochaete called Leptospira
icterohaemorrhagiae
Rats are the primary cause of the disease
Found in the kidneys of rats and is excreted in urine

23. Leptospirosis - Weil’s Disease
There is evidence that the spirochaete can pass through intact skin
Persons at risk include:
canal workers
sewer workers
agricultural workers
rat catchers
pig workers
butchers

24. Leptospirosis - Weil’s Disease
Primary control is through systematic destruction of rats in
infested areas
Prophylactic immunisation offers the best solution in sewer
workers
All “at risk” workers should carry a card warning of the dangers,
stressing personal cleanliness and hygiene, explaining the need
for protective clothing and alerting doctors to the possibility of
the disease

25. Leptospirosis - Weil’s Disease
It is essential that people subject to potential risk are:
aware of the causes and symptoms
given instruction in suitable first-aid precautions (e.g.
covering existing skin wounds, cleaning and disinfecting all
fresh wounds), notifying a GP if `flu-like symptoms occur and
notifying public authorities if rat infestation is noticed in a
work area

26. Fungi
Cause ill-health through inhalation of contaminated dust. Examples
include:
Extrinsic Allergic Alveolitis is a type of pneumoconiosis of biological origin caused
by exposure to organic dusts of vegetable and animal origin
Bagassosis is a similar disease to farmer’s lung resulting from exposure to
spores present in the cellulose fibres of cane-sugar after the sugar has been
extracted
Aspergillosis is an all-embracing term to describe the types of extrinsic allergic
Alveolitis (asthma) caused by the spores of the Aspergillus fungus, found as a
mould on cellulosic fibres such as hay, straw, jute, flax, hemp, sugar-cane

27. Fungi
Farmer’s Lung is a specific disorder caused by exposure to spores from
mouldy hay.
The disease is result of hypersensitivity due to an antigen present in the
dust.
Symptoms are often mistaken for `flu, with extreme shortness of breath on
exertion
Recovery is swift following removal of the individual from the dust source
However, with seasonal exposures the disease becomes chronic, leading
to pulmonary fibrosis, emphysema and bronchiectasis, by which time it
may be irreversible

28. Hepatitis
Those at risk include doctors, surgeons, nurses and porters
Infection amongst health workers is a result of contact with
blood or excreta of patients suffering from viral hepatitis or in
whom the disease is still in its incubation stage
Porters and refuse disposal are at risk from carelessly discarded
syringes and other sharps - the problem is becoming worse with
the increase in drug addiction

29. Hepatitis
Course of disease is similar to Weil’s Disease, but is usually much less
severe and normally self-limiting with recovery in about 6 weeks
In about 5% of cases, chronic infectious hepatitis follows, leading to
cirrhosis and possibly death
Persons exposed to risk can be protected with injections of gammaglobulin
In all cases, protective disposable gloves should be worn and hands and
arms washed regularly with disinfectant

30. AIDS
Acquired Immune Deficiency Syndrome
Caused by Human Immunodeficiency Virus (HIV), which
attacks the immune system
Virus is found in most body fluids but is delicate and relatively
easy to kill with heat and chemicals
It has low infectivity and transmission is thought to be more
likely with repeated exposure to infection rather than to a single
contact

31. AIDS
Occupational risk comes from accidental inoculation or
contamination of a cut or abrasion with blood or body fluids of
an infected person
Doctors, nurses, dentists, laboratory and hospital staff are at
some risk, since they may come into close contact with body
fluids
Other workers possibly at risk might include community,
welfare, custodial and emergency service workers and first
aiders

32. AIDS
Many of the precautions taken against other infections,
especially Hepatitis B, will be equally effective against HIV.
They include:
Prevention of puncture wounds, cuts and abrasions in the
presence of blood and body fluids; and the protection of existing
wounds and skin lesions
Control of surface contamination by containment and
disinfection
Safe disposal of contaminated waste, especially sharps