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Q fever

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

Causes

Q fever is found around the world and is caused by the bacteria Coxiella burnetii. These bacteria can infect:

  • Sheep
  • Goats
  • Cattle
  • Dogs
  • Cats
  • Birds
  • Rodents
  • Ticks

Infected animals shed these bacteria in:

  • Birth products
  • Feces
  • Milk
  • Urine

Humans usually get Q fever by breathing in contaminated droplets released into the air 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

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.

Common symptoms of early-stage (acute) Q fever may include:

  • Dry cough
  • Fever
  • Headache
  • Joint pain
  • Muscle pain

Other symptoms may include:

  • Abdominal pain
  • Chest pain
  • Rash
  • Yellow skin (jaundice)

Symptoms of long-term (chronic) Q fever may include:

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

Exams and Tests

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

  • Inflammation of the inside lining of the heart and heart valves
  • Flu-like symptoms
  • Inflammation of the liver
  • Pneumonia

Q fever is diagnosed with a blood antibody test.

Treatment

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

If you have the infection for more than 6 months, it is called chronic Q fever. Your health care provider may prescribe both doxycycline and hydroxychloroquine. You may need to take antibiotics for several months or years.

Outlook (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.

Possible Complications

Q fever may lead to these complications:

  • Bone infection
  • Brain infection
  • Inflammation of the heart valves, heart lining, or heart muscle
  • Liver infection
  • Lung scarring
  • Inflammation of the thin tissue that surrounds the brain and spinal cord
  • Pneumonia

When to Contact a Medical Professional

Tell your health care provider if you have symptoms of Q fever, especially if you believe you have been exposed to Coxiella burnetii. 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 their hands

Pasteurizing milk can also help prevent Q fever.

Prompt treatment can prevent early Q fever from becoming chronic.

Alternative Names

Query fever

References

Marrie TJ, Raoult D. Coxiella burnetii (Q fever). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 190.

Raoult D. Rickettsial infections. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 335.

Update Date: 12/7/2014

Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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