Q fever is caused by Coxiella burnetii, a bacterium that lives within host cells from mammals or ticks and survives for long periods of time in the environment. Q fever is generally transmitted from infected livestock and birds to humans (farmers, veterinarians etc.) or by exposure to contaminated aerosols. Many Q fever infections go unnoticed, but in some cases acute or chronic illness develops. Persons with acute Q-fever may show flu-like symptoms including high fever, severe headache, malaise, chills, nausea, vomiting, diarrhea, abdominal pain etc. Pregnant women, immunosuppressed persons, and patients with a preexisting heart-valve defect are at risk for developing chronic Q fever. The case fatality from Q fever is < 2% of hospitalized patients and treatment includes an antibiotics course that lasts 6-9 months. Q fever cannot be transmitted from person to person.
Small Q fever outbreaks are relatively common in the U.S. The last outbreak occurred in 2011 on goat farms in Washington and Montana where 20 people were identified positive for infection with C. burnetii. The most notorious occurrence of Q fever was in the Netherlands in 2008 where more than 2,200 confirmed human cases of Q fever were reported and as a result more than 50,000 dairy goats had to be slaughtered to contain the disease. More than half the cases of Q fever are reported in seven states that include Missouri and its neighboring states: Kentucky, Tennessee and Illinois. Around 3% of the healthy U.S. population and 10-20% of persons in high-risk occupations have antibodies to C. burnetii, suggesting previous exposure to the bacteria. There are currently no licensed vaccines for Q fever.
The infectious dose for Q fever is exceptionally low and it is estimated that only 10 bacterial cells is sufficient to cause disease in humans. Thus, until the recent construction of the Regional Biocontainment Laboratories such as the LIDR, understanding infection and immunity to Q fever was limited by the lack of facilities capable of protecting the laboratory worker from accidental infection. MU researchers at the LIDR are studying pulmonary Q fever and the mechanism of protective immunity against the disease. Their research has identified candidate vaccine approaches that are under development at the LIDR.
Images courtesy of the Centers for Disease Control and Prevention