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 24-45o
C. It does not survive about 60o
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
20o
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 20-45o
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