Q fever is an infectious disease that is spread from animals to people. It is caused by bacteria called Coxiella burnetii.
What is Q fever?
Q fever is an infectious disease that is spread from animals to people by the bacteria Coxiella burnetii. Cattle, sheep and goats are the most common source of human infection, but other animals such as kangaroos, bandicoots, camels, dogs and cats can also cause infection.
Infected animals generally do not become ill, though miscarriage or stillbirth may occur. Widespread contamination of the environment can result from infected animals shedding the bacteria in their urine, faeces, milk and in especially high numbers in birthing products, such as the placenta. Infected ticks living on animals can also shed the bacteria and contaminate the animal's hide, wool and fur.
People become infected with Q fever by inhaling contaminated aerosols and dust arising from:
- animals, animal products and waste (e.g. milk, wool, hides, fur, urine, faeces and birth products)
- animal environments (e.g. soil, bedding, straw, hay and grass)
- other contaminated items (e.g. machinery, equipment, vehicles and clothing).
Less commonly, infection occurs from consuming raw milk. Infection from tick bites and via person to person occurs rarely.
Many people who are infected with Q fever do not become sick or may have only a mild illness, sometimes mistaken for a cold or flu. Those who become acutely ill usually develop an influenza-like illness that can be severe and may require admission to hospital. Hepatitis (inflammation of the liver) is a common complication. Other complications include pneumonia, meningitis (inflammation of the lining of the brain and spinal cord) and inflammation of the heart. Most people make a full recovery, however it may take time to return to normal health.
Infection during pregnancy may cause complications such as miscarriage or the baby being born prematurely. Subsequent pregnancies may also be affected.
Around 20% of people with acute Q fever develop post-Q fever chronic fatigue syndrome, causing prolonged ill health and debilitating fatigue that lasts more than 12 months.
Less than 5% of infected people develop chronic Q fever. This condition, caused by persistent infection, can result in serious health issues months or years later. It most commonly causes endocarditis (inflammation of the lining of the heart) but can also cause lesions in internal organs, tissues and bone. Conditions including heart valve disorders, impaired immunity and pregnancy increase the risk of chronic Q fever.
It is important that people who work with animals, animal products and waste let their doctor know if they become ill with a flu-like illness. A doctor can test for Q fever, if indicated, and treat the person with antibiotics if they are infected.
Who is most at risk?
People who work with animals and animal products and waste are at risk of being infected with Q fever, especially new workers and visitors to animal-related industries.
Meat workers who work exclusively with pigs and town butchers working with dressed carcasses are not considered to be at an increased risk for Q fever.
Typical at-risk workers include:
- abattoir workers, contractors and visitors to abattoirs
- cattle, sheep and goat farmers and graziers
- dairy industry workers and those who work with raw milk
- shearers and wool classers
- tannery workers
- kangaroo shooters
- wild game and camel meat processing workers
- transporters of livestock, animal products and waste
- feedlot workers
- staff and students of agricultural education programs
- rendering plant workers
- pet food manufacturing workers
- wildlife and zoo workers and animal exhibitors
- laboratory workers handling veterinary specimens or working with Q fever bacteria
- workers in animal research facilities
- workers processing animal foetal products for the cosmetics industry
- veterinarians and veterinary nurses
- professional dog and cat breeders
- animal refuge workers
- laundry workers who handle clothing from at risk workplaces
- gardeners mowing in at-risk environments
- other people exposed to cattle, sheep, goats, camels, native wildlife, and animal products and waste.
The risk of infection is significant, as:
- Q fever is very infectious and people can become infected from inhaling just a few bacteria
- large numbers of bacteria are shed by infected animals
- the bacteria can survive in the environment for long periods, tolerate harsh conditions and spread in the air.
Prevention and control measures
Q fever vaccination
Q fever vaccination is the most important way to protect workers against infection. This requires pre-vaccination screening to exclude workers who have previously been infected with or vaccinated against Q fever, as they are at increased risk for a severe vaccine reaction.
Non-immune workers should be vaccinated and will develop immunity 15 days later. Workers who have completed Q fever screening and vaccination are able to store this information on the Q fever Register.
New workers to a business should undergo Q fever screening and vaccination before starting work. If this is not possible, they should undergo screening and vaccination as soon as possible after starting work and work in lower risk areas until they are known to be immune. If they need to enter higher risk areas, they should wear suitable respiratory protective equipment (RPE) as a short-term control measure and be properly trained in its proper fit and use.
Supporting control measures
Supporting control measures should also be implemented to protect other workers, visitors and members of the public from Q fever risks. These will vary according to the nature of the work and the level of risk, but the following are examples of additional ways to control the risk.
Level 1 control measures
Eliminate the risks associated with Q fever (e.g. restrict non-immune persons from visiting the workplace).
Level 2 control measures
Minimise the risks by substituting a work activity with something safer, such as:
- changing a high pressure water cleaning method with a low pressure water system to minimise airborne aerosols
- roster on immune workers for high risk locations and tasks.
Isolate the hazard such as:
- restrict non-essential and non-immune persons from entering Q fever risk areas
- isolate, enclose or contain the source of infection such as by installing enclosed visitor viewing areas at meatworks.
Use engineering and design controls to minimise exposure, such as:
- install ventilation systems to minimise the dispersal of airborne contaminants
- locate high traffic areas, car parks, site entry, offices and dining facilities away from higher risk areas
- install dust suppression systems to minimise airborne dust (e.g. water sprinklers)
- ensure that structures, surfaces, machinery and equipment are designed to be easily cleaned.
Level 3 control measures
Lower order control measures should be used to support higher order control measures.
- Use administrative controls, such as:
- develop safe work procedures to minimise Q fever risks
- provide workers with information, instruction and training on Q fever
- require contractors, labour hire workers and visitors to show proof of immunity to Q fever
- maintain a pool of Q fever immune contractors and casual workers
- keep the workplace clean to minimise the accumulation of dust and dirt
- use signage to inform people about Q fever risks and to use personal protective equipment (PPE)
- handle and dispose of animal products, waste, placenta and aborted fetuses appropriately, and where possible prevent animals from eating the placenta after giving birth
- provide suitable washing facilities for workers
- implement biosecurity measures to prevent the spread of infection between animals, e.g. tick treatments.
- Use PPE
- launder protective clothing (work clothes) on site or through a commercial laundry contractor, and kept separate from street clothing
- Respiratory protective equipment (RPE) can be used as an interim or short-term control measure to protect non-immune workers, contractors and visitors. The minimum level of RPE is a disposable P2 respirator. This must be of a suitable size and fit and worn by the worker. The worker is to be instructed in its correct use and fit.
Work-caused Q fever is a notifiable incident.
- Human health issues visit www.health.qld.gov.au or call 13HEALTH (13 43 25 84).
- Animal health issues, visit www.biosecurity.qld.gov.au or call 13 25 23.
- To find a Q fever vaccine provider or to register immune workers, contact the Q Fever Register on 1300 QFEVER (1300 733 837) or visit www.qfever.org.