Q Fever

Q Fever, tick-borne infectious disease, originally called Query fever. Caused by Coxiella burnetii, a type of bacterium known as a rickettsia, Q fever is characterized by a sudden onset of fever, malaise, headache, chest pains, and loss of appetite. The symptoms appear two to three weeks after the infection, and pneumonia often develops. The course of the disease runs from three to six days and rarely exceeds two weeks. The disease is generally free of medical complications, such as internal infections, and is seldom fatal.

Animals such as sheep, goats, and cows become infected with Q fever through contact with the feces of ticks infected with Coxiella burnetii. Inhaling infected dust from barns and pens also provides a pathway for the rickettsia into the animals’ digestive tract and milk. Humans contract the disease by inhaling infected dust from animals and their feces; ingesting raw, unpasteurized milk; or handling infected animals. Slaughterhouse and dairy workers, herders, and tanners are most at risk for contracting Q fever. The disease is not transmitted between humans.

Diagnosis involves testing blood samples for the presence of Q fever antibodies, the body’s defense mechanism against the rickettsia infection. If taken early enough in the infection’s progress, antibiotics can provide an effective cure for Q fever. In addition to fever symptoms, about one-third of patients also suffer from hepatitis. In extreme cases the heart’s aortic valve can become infected, a condition called endocarditis that is treated with surgery to replace the damaged heart valve. Recovery from Q fever proceeds slowly for several weeks; muscle weakness is the principal disability. It is not unusual for patients to lose 7 to 9 kg (15 to19 lb) during the course of the illness. Potent rickettsia vaccines have been developed that offer considerable protection from the disease. Control of Q fever depends primarily on immunization of those workers most likely to contract the disease.