Zoonoses are diseases of animals that can cause serious illness in people.
About 50 zoonoses have been recorded in Australia. The two most common zoonoses in Western Australia are LEPTOSPIROSIS and Q FEVER. Those most likely to be infected by zoonoses include abattoir workers (see checklist), farm workers, shepherds, shearers, wool sorters, veterinary personnel, pelt and hide tanners, livestock handlers and animal laboratory workers.
Brucellosis has been virtually eradicated in WA, though a few people may still carry this disease. Anthrax and the Hendra virus are considered unlikely to occur in WA. Further information on Anthrax is provided in Anthrax: Public health response plan for Australia. Psittacosis, from exposure to birds, occurs occasionally in WA (less than 10 cases per year).
As zoonoses hazards vary with the type and condition of animals, and the nature of the work being done, safe work procedures, including training, instruction and supervision of employees, should be established through consultation between employers and employees or their safety and health representatives.
How are Leptospirosis and Q fever transmitted?
Leptospirosis is most common in pigs and cattle, but sometimes occurs in sheep, dogs and cats.
Leptospirosis is usually contracted from the urine of infected animals or from contaminated water. The bacteria enters the body through cuts in the skin and through the linings of the eyes, nose or throat.
Q fever is found in cattle, dairy cows, sheep, goats, bandicoots, kangaroos and wallabies. It may be transmitted by inhaling infected material - including contaminated dust - from the afterbirth, birth fluids and excreta of infected animals. The infectious agent, Coxiella burnetii, may be highly concentrated in animal tissues (especially the placenta) and is resistant to disinfectants. You can also catch Q fever by drinking infected, unpasteurised milk, and by contact with contaminated straw, wool, hair or hides.
Animals carrying Leptospirosis or Q fever may not appear to be sick.
Catching either disease from another infected person is extremely rare.
Symptoms and effects
Initially, both Leptospirosis and Q fever feel like the flu. You may have muscle pains, severe headaches and fever.
As Leptospirosis takes hold, you may also have chills, a stiff neck, and be sensitive to light. All symptoms usually ease within 10 days, but may recur.
A serious form of Leptospirosis may cause vomiting and jaundice (yellowing of the skin and eyes). The kidneys may be affected and internal bleeding may occur, and at this stage it can be fatal.
Q fever may progress from high fever, muscle pain and headache to pneumonia. Some people also develop liver and heart problems. Some people experience ongoing fatigue after the initial disease has resolved. This is known as Post Q Fever Fatigue Syndrome.
What is the treatment?
Both Leptospirosis and Q fever can be treated with antibiotics. If you think you may be infected with either disease, see a doctor quickly.
Tell the doctor you have been in contact with animals and may have caught a disease from them.
In the case of either disease, a blood test is needed to confirm infection.
Employees in workplaces where zoonoses may be a hazard should be given information on zoonoses, and be trained in safe work procedures to minimise infection risks.
Suitable hygiene facilities, including facilities for hand washing, cleaning, and provision for laundering contaminated clothing will help reduce zoonoses risks. Engineering and ventilation systems should also be designed to reduce the risk of infection, however if risks can’t be reduced sufficiently, employees should be provided with suitable personal protective equipment, and trained in its correct use, storage and maintenance.
Safe work procedures to be considered include the following:
- Vaccinating livestock (in consultation with a vet).
- Avoid contact with water that may be contaminated.
- Clean benches and floors with detergents or disinfectants.
- Immediate treatment of abrasions and wounds, which should be covered with a waterproof dressing. Attention to personal hygiene and prompt washing of skin and eyes if contaminated by animal urine.
- Eradicate rats and mice.
- Farm areas should have good drainage and effluent should be hygienically disposed of.
- Pigs and cattle should be raised separately where possible.
- Pigs are more likely to get the disease if they are kept in paddocks or on dirt floors. If possible, use concrete or mesh floors instead.
Vaccination (see the following section) is the preferred primary method of preventing Q fever.
Ventilation systems in abattoirs must be designed so the outlet and intake are far enough apart to prevent contaminated material ejected from the outlet being drawn in by the intake. In addition there should be local exhaust ventilation to remove airborne contamination.
- All those who work with animals should be protected from breathing contaminated dust or fluid droplets.
- Any material that may be infected should be disinfected or disposed of hygienically.
- Treat any cuts quickly with disinfectant.
- Burn afterbirth and contaminated litter.
- Milk should be pasteurised or boiled before drinking.
An effective vaccine is available to protect workers at risk from Q fever. People who are vaccinated and most people who get Q fever are immune for life. People who work with animals often become immune naturally. Vaccination is recommended where people are exposed to a Q fever hazard. People who already have immunity must not be given the vaccine, otherwise there may be unpleasant local reactions. Testing for immunity is always performed prior to vaccination. A register of Q fever immune status is stored in the Australian Q Fever Register.
With Leptospirosis, there are many strains throughout the world, and some countries have developed vaccines against local strains. Human Leptospirosis vaccine is not available in Australia, but there is a vaccine for livestock. Reducing the incidence of the disease in livestock reduces the risk of transmission to workers. People who catch Leptospirosis develop protection against strains they have had.
Section 19.1 of the Occupational Safety and Health Act 1984 requires an employer to provide and maintain a workplace in which employees (including contractors and labour hire workers) are not exposed to a hazard. Employers also have a duty of care under Section 21 of the Act in relation to the safety and health of visitors. Employers are required under Regulation 3.1 of the Occupational Safety and Health Regulations 1996 to identify hazards and assess risks.
In some workplaces, zoonoses are a hazard requiring identification, risk assessment and risk control. If an employee contracts Q fever, leptospirosis, anthrax or brucellosis in the course of work involving animal or animal product handling, the employer is required under Section 23I of the Act to report the disease to WorkSafe.
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