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Q fever

Definition

Q fever is a bacterial infection that can affect the lungs, liver, heart, and other parts of the body.

Alternative Names

Query fever

Causes, incidence, and risk factors

Q fever is found around the world and is caused by the bacteria Coxiella burnetii. The bacteria affects sheep, goats, cattle, dogs, cats, birds, rodents, and ticks, as well as some other animals. Infected animals shed this bacteria in:

• Birth products
• Feces
• Milk
• Urine

Humans usually get Q fever by breathing in contaminated droplets released by infected animals. Drinking raw milk has also caused infection in rare cases. People at highest risk for this infection are:

• Farmers
• Laboratory workers who work with Coxiella burnetii
• Sheep and dairy workers
• Veterinarians

Chronic Q fever develops in people who have been infected for more than 6 months.

People at highest risk include those with heart valve problems or weakened immune systems.

Symptoms

It usually takes about 20 days after exposure to the bacteria for symptoms to occur. Most cases are mild, yet some severe cases have been reported.

Symptoms of acute Q fever may include:

• Chest pain with breathing
• Clay-colored stools
• Cough
• Fever
• Headache
• Jaundice
• Muscle pains
• Rash (not common)
• Shortness of breath

Symptoms of chronic Q fever may include:

• Chills
• Fatigue
• Night sweats
• Prolonged fever
• Shortness of breath

Signs and tests

The health care provider will suspect Q fever in people who have been exposed to the Coxiella burnetii bacteria who develop:

• Endocarditis
• Flu-like symptoms
• Hepatitis
• Pneumonia

Q fever is diagnosed with a blood antibody test (serology).

Treatment

The main treatment for Q fever is with antibiotics. For early-stage (acute) Q fever, doxycycline is the recommended antibiotic.

For chronic Q fever, a combination of doxycycline and hydroxychloroquine is often used. You may need to take antibiotics for several months.

Support Groups

Expectations (prognosis)

The outlook for people who get treated in the early stages of Q fever is generally good.

Chronic Q fever requires long-term treatment with antibiotics. Your health care provider should check you often to make sure the disease has not returned.

Complications

• Cirrhosis, hepatitis, and other liver problems
• Encephalitis
• Infection of the heart valves (endocarditis)
• Inflammation of the heart lining (pericarditis)
• Inflammation of the heart muscle (myocarditis)
• Lung scarring (interstitial pulmonary fibrosis)
• Meningitis
• Pneumonia

Calling your health care provider

Notify your medical provider if you have symptoms of Q fever, especially if you believe you have been exposed to the bacteria. Although many different illnesses can cause similar symptoms, you may need to be evaluated for Q fever.

Prevention

People at risk (for example, farmers and veterinarians) should always:

• Carefully dispose of animal products that may be infected
• Disinfect any contaminated areas
• Thoroughly wash your hands

Pasteurizing milk can also help prevent Q fever.

Prompt treatment can prevent early Q fever from becoming chronic.

References

Marrie TJ, Raoult D. Coxiella burnetii (Q fever). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 189.