Q Fever

Q Fever is an infectious disease caused by the bacterium Coxiella burnetii. The organism is mainly transmitted by the respiratory route by droplet infection through aerosols, or inhalation of 'dry' organisms in infected dust. C. burnetii can be found in milk, excreta and the placentae of infected farm animals, particularly goats, sheep and cows.

Signs And Symptoms

Most of the time it manifests as a brief unremarkable illness that can resemble nearly any infectious disease, or it can have no symptoms at all. Less than 40% of cases develop a severe flu-like illness with high fevers and headache, muscle aches and pains and pneumonia may occur. Liver and heart complications may also occur. Most cases will resolve within two to six weeks. It can be a serious disease if there is heart involvement, which occurs in about 2% of cases.

Are You At Risk?

Q Fever is found worldwide in domestic and farm animals. It is also found in many species of ticks, and wild and domesticated mammals, marsupials and birds. It is usually an occupational disease, which affects people who have direct contact with animals such as farmers, abattoir workers, vets and livestock transport workers. Those at high risk are non-immune new employees or visitors to animal related industries.

How Is It Spread?

The most commonly identified sources of human infection are farm animals such as cattle, goats and sheep. The usual transmission to humans is via the respiratory route. The bacteria is resistant to heat, drying and sunlight; it may therefore lay dormant in materials such as dust, which has been contaminated by infected animal body fluids, e.g. blood, urine, faeces and birth products (placenta). Inhalation of such contaminated material may result in infection. Ingestion of infected, unpasteurised milk or dairy products can also cause infection (but not as consistently as infection by inhalation). It usually takes two to three weeks from contact with the bacteria to the development of the illness. The disease is rarely, if ever transmitted from person to person.

Treatment

Treatment with antibiotics can suppress the symptoms and shorten the course of the illness, but does not always eradicate the infection. In complicated cases treatment may need to continue for an extended period of time. Occasionally surgery may be required if the heart valves are damaged as a result of chronic infection. Immunity following infection is probably life long.

Prevention

How can the spread of disease be controlled?

Outbreaks of Q Fever occasionally occur. Control of an outbreak requires identification of the source of the infection and elimination if possible. Educating people who are at risk of exposure is important.

What can be done to prevent the disease?

Vaccination

Vaccination gives a high level of long term protection against Q Fever. Those at risk of exposure should be vaccinated. Before being vaccinated you must first be tested to see if you have been exposed to Q Fever in the past. This involves a blood test and skin tests. If there has been past exposure and you are vaccinated there is a risk of an abscess forming at the injection site. People who prove to have positive past exposure will have a level of immunity and are unlikely to get symptomatic Q Fever. Boosters are not considered necessary.

Vaccination should not be given to those who are allergic to eggs.

Protective Clothing

Gloves, overalls and facemasks should be worn when slaughtering animals or dressing carcasses.

Personal Disinfection

Thoroughly wash your hands and arms in soapy water after handling animals or carcasses.

Site Or Equipment Disinfection

Wash off all urine, faeces, blood and other body fluids.

Thoroughly disinfect using either a 1:100 dilution of household bleach with tap water or 5:100 dilution of peroxide or 1:100 dilution of Lysol.

Minimise dust and rodents in slaughter areas and animal housing areas.

Yard facilities for sheep and cattle should be sited well away from domestic living areas.

© 2014, Travel Medicine Centre Perth