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Q fever
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Causative agent
Q fever (Query fever) is a zoonotic infection caused by Coxiella burnetii. The organism is found in farm animals (especially cattle, sheep and goats), domesticated pets, some wild animals, birds and ticks. The infection exists worldwide and usually affects meat workers and farmers.
Clinical features
Acute infection of Q fever may present with high fever, chills, severe headache, muscle pain, malaise and weight loss. Severe diseases include acute hepatitis, chest infection and infection of the brain and its membrane (meningoencephalitis). Asymptomatic infection may also occur.
Some people may develop a chronic form of the disease, where symptoms persist for months to years after acute infection. A serious complication of chronic Q fever is infection of heart valves (endocarditis), particularly in persons with underlying heart diseases. Transplant recipients, cancer patients and those with chronic kidney disease are at risk of developing chronic Q fever.
Mode of transmission
Q fever is mainly transmitted through inhalation of particles contaminated by placental tissues, birth fluids and excreta of infected animals. It can also be spread by direct contact with infected animals and their produce, or consuming unpasteurised dairy products. Transmission via a tick bite and person-to-person transmission are rare.
Incubation period
The incubation period is usually 2 to 3 weeks.
Management
Q fever can be treated by antibiotics. For acute Q fever, the treatment generally lasts for about 2 to 3 weeks; for chronic Q fever, however, the treatment can last for 2 years or even longer.
Prevention
At present, there is no vaccine against Q fever available in Hong Kong. The public should adopt the following measures to reduce the risk of infection:
- Avoid contact with farm or wild animals
- Observe good personal and food hygiene; dairy products should be pasteurised before consumption
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