Health Encyclopedia

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 without effective treatment.

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.

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

Baoult D. Rickettsioses. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 348.

Review Date:9/28/2008
Reviewed By:Jatin M. Vyas, MD, PhD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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