Facts about Q fever

factsheet

Q fever is a common zoonosis (infection that could transmit from animals to humans), caused by Coxiella burnetii. Natural reservoirs include several domestic and wild animals, most of which show no signs of disease (although infection can cause abortions). Due to the high resilience in the environment of Coxiella, humans are most often infected by inhalation of aerosols produced in contaminated locations, but other modes of infection have been documented (including food-borne).
 
After an incubation period of, usually, 2–3 weeks, disease symptoms may appear but more frequently they do not. A serious clinical picture can suddenly emerge characterised by high fever, eye infection, respiratory tract infection, and severe headache. Occasionally, the infection takes a chronic course, leading to infection of the heart valves, hepatitis and other organ involvement. Acute cases respond to appropriate antibiotic treatment but infected heart valves may require surgery.
 
The mainstays of prevention aim at avoiding the production and inhalation of contaminated dust and the consumption of potentially contaminated food (e.g. unpasteurised milk).

Q fever is…

…an infectious disease caused by bacteria called Coxiella burnetii that affects both humans and animals. The “Q” comes from “query” fever, the name of the disease until its true cause was discovered in the 1930s. Q fever can be a mild illness or a more severe disease that can cause death.

Symptoms

Some people who get Q fever will have no symptoms. Others will experience sudden headaches, fever, chills, muscle soreness and, in some cases, pneumonia. Other symptoms can include fatigue, chills, night sweats, weight loss, joint pain and nausea/vomiting. Some symptoms such as fatigue can be long-lasting.

Complications

In a very small number of cases (around 1%), Q fever leads to a more serious illness known as chronic Q fever, sometimes after a number of years. The most common symptom of chronic Q fever is inflammation of the inner lining of the heart (endocarditis), which can be deadly if not treated. Hepatitis (inflammation of the liver) and osteomyelitis (inflammation of the bone or bone marrow) may also occur.

Ways to catch Q fever

Human infection with Q fever is normally caused by contact with an infected animal, most commonly sheep, goats and cattle. With sheep and cattle, the bacteria that cause Q fever can grow in large numbers in the female’s uterus and udder. Therefore, humans can catch the infection through contaminated milk or when they come into contact with the foetus, placenta or fluids from when an animal gives birth. The bacteria can survive in dry dust for months; consequently, Q fever can be caught through contact with contaminated farm products such as wool, hair, straw or hay.

People most at risk

Anybody who works with cattle, sheep or products produced from them is at an increased risk of catching Q fever, including the following occupations: farm workers, slaughterhouse workers, workers in meat-packing plants, veterinarians and wool workers.

Severe disease has been reported in the foetus; therefore pregnant women are at risk of passing the infection on to their babies. The disease can also be particularly severe in newborn babies. People who have problems with their heart valves are at increased risk of contracting endocarditis (inflammation of the inner lining of the heart).

Diagnosis

Q fever is diagnosed through examination of a blood sample from the patient.

Treatment

Q fever can be treated effectively with antibiotics. Chronic Q fever is more difficult to treat and usually requires a longer course of antibiotic therapy.

How to avoid getting Q fever

Good hygiene practices in premises dealing with animals—particularly with sheep, cattle and goats—will help prevent transmission of the bacteria that causes Q fever. As the disease can be transmitted to humans through contaminated milk, pasteurisation of milk and milk products will help prevent infection.

The information contained in this factsheet is intended for the purpose of general information and should not be used as a substitute for the individual expertise and judgement of healthcare professionals.