Q fever is an infection caused by the bacterium Coxiella burnetii. Q fever is usually a mild disease with flu-like symptoms. Many people have no symptoms at all. In a small percentage of people, the infection can resurface years later. This more deadly form of Q fever can damage your heart, liver, brain and lungs.

Q fever is transmitted to humans by animals, most commonly sheep, goats and cattle. When you inhale barnyard dust particles contaminated by infected animals, you may become infected. High-risk occupations include farming, veterinary medicine and animal research.

Mild cases of Q fever clear up quickly with antibiotic treatment. But if Q fever recurs, you may need to take antibiotics for at least 18 months.

Many people infected with Q fever never show symptoms. If you do have symptoms, you'll probably notice them between three and 30 days after exposure to the bacteria. Signs and symptoms may include:

  • High fever, up to 105 F (41 C)
  • Severe headache
  • Fatigue
  • Cough
  • Nausea
  • Diarrhea
  • Sensitivity to light

Q fever is caused by the bacterium Coxiella burnetii, commonly found in sheep, goats and cattle. The bacterium can also infect pets, including cats, dogs and rabbits.

These animals transmit the bacteria through their urine, feces, milk and birthing products — such as the placenta and amniotic fluid. When these substances dry, the bacteria in them become part of the barnyard dust that floats in the air. The infection is usually transmitted to humans through their lungs, when they inhale contaminated barnyard dust.

Certain factors can increase your risk of being infected with Q fever bacteria, including:

  • Occupation. Certain occupations place you at higher risk because you're exposed to animals and animal products as part of your job. At-risk occupations include veterinary medicine, meat processing, livestock farming and animal research.
  • Location. Simply being near a farm or farming facility may put you at higher risk of Q fever, because the bacteria can travel long distances, accompanying dust particles in the air.
  • Your sex. Men are more likely to develop symptomatic acute Q fever.
  • Time of year. Q fever can occur at any time of the year, but the number of infections usually peaks in April and May in the U.S.

Risks for chronic Q fever

The risk of eventually developing the more deadly form of Q fever is increased in people who have:

  • Heart valve disease
  • Blood vessel abnormalities
  • Weakened immune systems
  • A type of kidney disease known as chronic renal insufficiency

A Q fever recurrence can affect your heart, liver, lungs and brain, giving rise to serious complications, such as:

  • Endocarditis. An inflammation of the membrane inside your heart, endocarditis can severely damage your heart valves. Endocarditis is the most deadly of Q fever's complications.
  • Lung issues. Some people who have Q fever develop pneumonia. This can lead to acute respiratory distress, a medical emergency in which you're not getting enough oxygen.
  • Pregnancy problems. Chronic Q fever increases the risk of miscarriage, low birth weight, premature birth and stillbirth.
  • Liver damage. Some people who have Q fever develop hepatitis, an inflammation of the liver that interferes with its function.
  • Meningitis. Q fever also can cause meningitis, an inflammation of the membrane surrounding your brain and spinal cord.

You might first visit your primary care doctor because of your symptoms. He or she might refer you to an infectious disease specialist.

Here's some information to help you get ready for your appointment, and what you might expect from your doctor.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if you need to do anything in advance, such as restrict your diet.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins or supplements that you're taking.
  • Write down questions to ask your doctor.

Preparing a list of questions can help you make the most of your appointment time. For Q fever, some basic questions to ask your doctor include:

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need? Do these tests require any special preparation?
  • Is this condition temporary or long lasting?
  • What treatments are available, and which do you recommend?
  • What types of side effects can I expect from treatment?
  • Are there any alternatives to the primary approach that you're suggesting?
  • I have other health conditions. How can I best manage these conditions together?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

  • When did you first begin experiencing symptoms?
  • Do you have symptoms all the time or do they come and go?
  • Does anything seem to improve or worsen your symptoms?
  • Have you ever been diagnosed with heart valve problems or had heart surgery?
  • Have you been exposed to any barnyard or livestock environments recently?
  • Have you come into contact with newborn animals within the past few weeks?
  • Do you live near a large farming area?
  • Are you pregnant?
  • Have you recently traveled abroad?

To diagnose Q fever, your doctor will perform one or more blood tests, along with additional tests if chronic Q fever is suspected.

Lab tests

Your doctor may want to check your blood for antibodies to the Coxiella burnetii antigen and for evidence of liver damage.

Imaging tests

  • Chest X-ray. Q fever can cause pneumonia in some people. A chest X-ray can be used to see if your lungs look healthy.
  • Echocardiography. If chronic Q fever is suspected, your doctor may do an echocardiogram to check for problems with your heart valves.

Q fever is treated with the antibiotic doxycycline. How long you take the medicine depends on whether or not you have acute or chronic Q fever. For acute infections, antibiotic treatment lasts two to three weeks.

People who have chronic Q fever usually must take a combination of antibiotics for at least 18 months. Even after successful chronic Q fever treatment, you'll need to go back for follow-up tests for years in case the infection returns.

Mild or nonsymptomatic cases of acute Q fever often get better on their own with no treatment. However, if you have symptoms of Q fever, antibiotic treatment is recommended.

If you have Q fever endocarditis, you may need surgery to replace damaged heart valves.

A Q fever vaccine is available in the United States. A different vaccine that originated in Australia has been studied more thoroughly, but it's not available in the U.S. You may want to consider vaccination if you're at high risk of developing Q fever complications and you work in an environment that may expose you to the disease.

Whether you're at high risk of Q fever or not, it's important to use only pasteurized milk and pasteurized milk products. Pasteurization is a process that kills bacteria.

Jul. 24, 2014