Q fever is an infectious disease caused by a species of bacteria usually found in sheep, goats and cattle. Humans working in livestock occupations may be at risk. Q fever usually spreads to people through the inhalation of contaminated barnyard dust.
Q fever can occur either in an acute or a chronic form. The acute form is milder and characterized by flu-like symptoms. The chronic form lasts longer and has more serious effects on your body.
The name Q fever emerged after the disease was called Query fever following an outbreak in the 1930s in Queensland, Australia. The illness is uncommon, but experts believe it is underreported and often goes unrecognized. It occurs around the world.
With acute Q fever, you'll likely recover fully within a few months with little or no treatment or much sooner after antibiotic treatment. Chronic Q fever requires lengthier treatment.
Coxiella burnetii bacteria cause Q fever and can affect vital organs of your body, including your heart, brain, liver and lungs. The bacteria can enter your body in a variety of ways, including :
- Inhalation : If you live or work around animals — even domesticated pets — you may be at risk of breathing in infected particles. Mammals transmit the bacteria through their urine, feces and placenta. Also, the coats of newly born animals may carry the bacteria. While goats, cattle and sheep are usually the cause of outbreaks in rural areas, domesticated dogs, cats, birds and rabbits are often responsible for outbreaks in urban areas.
- Ingestion : Drinking unpasteurized milk puts you at greater risk of infection.
- Through the skin : The bite from an infected tick may inject the bacteria directly into your bloodstream.
People who work in a barnyard or livestock environment may risk inhaling infected droplets or dust particles because of their proximity to animals. Away from these environments, the risk of Q fever is extremely low. A few cases every year stem from contact with a dog or cat that may have become infected through a tick bite.
Chronic Q fever is a much more serious and possibly life-threatening illness. If you have gone many months with untreated Q fever, and have had cancer, heart valve problems, kidney problems, or difficulty recovering from illness because of a weakened immune system, you're at risk of chronic Q fever.
When to seek medical advice :
If you've been exposed to any barnyard or livestock environments within the last three weeks and develop flu-like symptoms, talk to your doctor. Q fever is rare, so your symptoms are likely due to a condition other than Q fever. Still, it's best to identify the cause of your symptoms.
Many people exposed to the bacterium that causes Q fever never become sick. People who do get sick with acute Q fever may encounter the following flu-like signs and symptoms two to three weeks after exposure :
- High fever (up to104 or 105 F)
- Severe headache
- Sore throat
- Dry cough
- Muscle pain
- Abdominal pain
- Chest pain
- Clay-colored stools
- Yellowish discoloration of the skin and eyes (jaundice)
- Weight loss
In addition, many people with acute Q fever also develop pneumonia and liver inflammation (hepatitis).
Finally, some people with acute Q fever may also develop these other manifestations :
- A purplish rash caused by hemorrhaging of small blood vessels near the skin's surface
- Inflammation of the heart's surrounding membrane (pericarditis)
- Inflammation of the heart's muscular wall (myocarditis)
- Inflammation of the fluid surrounding the brain and spinal cord (meningitis) or of the brain (encephalitis)
Chronic Q fever
Chronic Q fever is a more severe illness and defined as lasting more than six months. The chronic form may develop months and even years after an acute infection of Q fever. It's a serious and often fatal form of Q fever.
Signs and symptoms of chronic Q fever may include :
- Prolonged fever
- Night sweats
- Shortness of breath
Q fever endocarditis
The most common clinical feature of chronic Q fever is inflammation of the heart's inner lining (endocarditis). Left untreated, endocarditis can result in damage to or destruction of the heart's valves.
Q fever endocarditis occurs most often in people with previous heart valve disease, a compromised immune system, cancer, chronic kidney disease and in people who've received transplants.
The flu-like symptoms associated with this infection aren't unique to Q fever. In an effort to narrow the possibilities, your doctor may ask if your medical history contains any links to endocarditis, pneumonia or hepatitis — all problems associated with Q fever. Also, because environmental factors play a large role in acquiring this infection, your doctor may ask about your recent exposure to areas that may have placed you at risk of acquiring Q fever infection. A blood test then can confirm the diagnosis.
Q fever may lead to a number of complications :
- Infection of your heart valves (endocarditis)
- Inflammation of your liver (hepatitis)
- Inflammation of your brain (encephalitis)
Q fever in pregnancy
In pregnancy, both acute and chronic Q fever can result in spontaneous abortion, premature birth and low birth weight.
Mild cases of acute Q fever may get better on their own without any specific treatment.
If you've been diagnosed with Q fever, antibiotics are the most common treatment. The severity of the infection determines the specific antibiotics and the length of time you'll need to take them.
Treatment for acute Q fever — the less severe form of the disease — takes two to three weeks, and the outcome is generally positive. Treating chronic Q fever — the more severe and complex form of the disease — takes numerous treatments of antibiotics and much more time, perhaps up to three years. Relapses are common in severe cases, so follow-up visits to your doctor may be frequent.
If you're at risk of Q fever, following these recommendations may prevent infection :
- Carefully dispose of animal products. Q fever affects mostly people who work in environments with sheep, goats and cattle, as the byproducts of an animal birth (including placenta and fetal membranes) can carry the bacteria. Properly dispose of all animal waste material.
- Use disinfectants. Use specific cleaners and disinfectants labeled effective against C. burnetii bacteria.
- Wash your hands. A thorough washing of your hands throughout the day may prevent the spread of this and other bacteria.
- Drink only pasteurized milk. Unprocessed dairy products may carry harmful bacteria.
- Get vaccinated. A tested and highly effective vaccine is available in Australia, though the vaccine is not commercially available in the United States.
If you develop flu-like symptoms in the weeks following exposure to an animal environment that may carry a risk of Q fever, see your doctor. The sooner you treat Q fever, the less likely it will become severe.