Q fever, or query fever, is an uncommon bacterial infection transmitted from animals to humans. It can be acute or chronic, and the chronic type can be fatal.
Sheep, goats, cattle and other livestock are most likely to carry the bacterium, but it has been found in many types of animals including fish, dogs, camels, and guinea pigs.
Q fever can occur anywhere in the world. In 2014, 167 cases of Q fever were reported in the United States (U.S.).
The infection is called Query fever because, when it was first identified, the cause was a mystery. The cause has since been identified, but use of the name has continued.
There are two main types: acute and chronic.
Acute Q fever
Q fever is carried and spread by livestock.
This type is more common and less serious. Flu-like symptoms occur, including muscle pain and an elevated body temperature, or fever. Rarely, mild pneumonia, hepatitis, or both may develop.
Most patients with acute Q fever make a full recovery within a few weeks without treatment. Antibiotics can help relieve symptoms within a few days.
However, in some people, it can become chronic, especially in people who already have another chronic condition.
Chronic Q fever
Chronic Q fever is far less common but more serious. The inner lining of the heart may become inflamed, known as endocarditis.
This could lead to heart failure if left untreated.
Other complications of chronic Q fever can include:
encephalitis, or inflammation of the central nervous system (CNS)
pneumonia, or inflammation of the lungs
hepatitis, or inflammation of the liver, which presents as liver enlargement, fever, and yellowing of the skin and eyes (jaundice)
osteomyelitis, or infection of the bones
Chronic Q fever is usually fatal if left untreated.
The outlook for patients with chronic Q fever depends on whether they have access to antibiotics. With timely treatment, the survival rate is 90 percent.
People with chronic Q fever commonly have to take antibiotics for several years to prevent recurrence.
Signs and symptoms develop between 14 and 21 days after the initial infection. This is known as the incubation period.
Signs and symptoms of acute Q fever include:
fever, with a body temperature of at least 39.4 degrees Celsius, or 104 degrees Fahrenheit
photophobia, or sensitivity to light
skin rash, although this is rare
hepatitis, or inflammation of the liver, but this is rare
The signs and symptoms of Chronic Q fever appear about 6 months after the acute manifestation.
The most common symptom is endocarditis.
Chronic cases of Q fever can lead to fatal heart complications.
Symptoms of endocarditis include:
a high temperature
a new heart murmur
alterations in a heart murmur
bleeding under fingernails or toenails
broken blood vessels in the eyes
broken blood vessels in the skin
shortness of breath
small lumps on fingers and/or toes
shortness of breath
sweating including night sweats
swelling of the abdomen
swelling of limbs
unexpected weight loss
Osteomyelitis, a bone infection, may also occur. Patients typically experience deep pain and muscle spasms in the inflammation area, as well as fever.
Colorado tick fever: Symptoms, treatment, and prevention
The chance of catching a disease from an animal is low, but parasites, such as ticks, that feed on both animals and humans can cause health problems.
Working on or near a farm and its animals can lead to an increased risk of contracting Q fever.
People who have frequent contact with livestock face a significantly higher risk of developing Q fever. This includes farmers, veterinarians, stablehands, meat packers, and slaughterhouse workers.