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Q fever

Definition

Q fever is an infection caused by the bacteria Coxiella burnetii, which 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 urine, feces, birth products, and milk.

Humans usually acquire Q fever by inhaling contaminated droplets excreted by infected animals. Consumption of raw milk has also been associated with infection in rare cases. People at highest risk for this infection are veterinarians, farmers, sheep and dairy workers, as well as laboratory workers who work with this organism.

The incubation period (time from exposure to the development of symptoms) for early (acute) Q fever is approximately 20 days. In acute Q fever, the three main sets of symptoms include flu-like syndrome, pneumonia, and hepatitis. Flu-like syndrome usually goes away on its own, lasts up to 3 weeks, and may involve high fevers, headaches, and muscle aches.

Pneumonia can occur in up to a third of individuals. Most cases are relatively mild and include fever and cough, yet some severe cases have been reported. Hepatitis is another common outcome of Q fever. Other less common features of acute Q fever include rashes, meningitis, myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of heart lining).

Chronic Q fever develops in individuals who have been infected for over 6 months without effective treatment. Its main sign is infection of the heart valves termed endocarditis.Other less common features of chronic Q fever are cirrhosis and lung scarring (interstitial pulmonary fibrosis).

Individuals at highest risk include those with underlying heart valve problems, as well as people with weakened immune systems.

Symptoms

Symptoms of acute Q fever may include:

• Fever
• Headache
• Muscle pains
• Cough
• Chest pain upon breathing
• Shortness of breath
• Jaundice
• Clay-colored stools

Symptoms of chronic Q fever may include:

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

Signs and tests

The diagnosis of Q fever should be suspected in individuals with appropriate exposure histories who develop flu-like symptoms, pneumonia, hepatitis, or endocarditis. Q fever is diagnosed with a blood antibody test (serology).

Treatment

The cornerstone of treatment for Q fever is antibiotic therapy. For acute Q fever (early stage) doxycycline is the recommended agent. For chronic Q fever, a combination of doxycycline and hydroxychloroquine is frequently used.

Expectations (prognosis)

The prognosis for people who get treatment in the early stages of Q fever is generally good. Chronic Q fever requires prolonged treatment with antibiotics and requires frequent monitoring for relapses.

Complications

• Endocarditis
• Long-term hepatitis and liver problems
• Encephalitis

Calling your health care provider

Notify your medical provider if you develop the above mentioned symptoms, in particular if you have a compatible exposure history. While there are many different illnesses that can cause similar symptoms, you may need to be evaluated for the possibility of Q fever.

Prevention

People at risk (for example, farmers and veterinarians) should always thoroughly dispose of potentially infectious animal products and disinfect any contaminated areas. This includes thoroughly washing the hands.

Pasteurization of milk can also help prevent Q fever.

Prompt treatment can prevent early Q fever from becoming chronic.

Review Date:9/25/2006
Reviewed By:Charlotte Grayson, MD, Private Practice specializing in Internal Medicine and Infectious Disease, Smyrna, GA. Review provided by VeriMed Healthcare Network.

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