Coxiella burnetii (C. burnetii), the bacterium that causes Q fever, gets transmitted by inhalation and remains extremely stable in the environment. It has a very low infectious dose (very few bacteria can cause illness), making it a potential agent for bioterrorism. These factors have led to inclusion of C. burnetii on the Health and Human Services list of Select Agents. Cattle, sheep, and goats commonly get infected with C. burnetii. People, especially those who handle farm animals, can become exposed to C. burnetii by breathing in dust contaminated from infected animal body fluids. The bacterium can exist in two antigenic phases. Phase I can replicate in healthy animals and is infectious for humans. Infection with Phase 1 C. burnetii can result in acute or chronic Q fever. Acute Q fever is a flu-like illness that can result in pneumonia or hepatitis. Chronic Q fever is a more serious disease which usually presents as endocarditis or vascular infection. Culture of C. burnetii in the laboratory can result in Phase II organisms. The Phase II variants cause little to no illness in animal models but can be useful for detection of antibodies in humans or animals infected with Phase I. C. burnetii infection in pregnant women may also result in abortions, premature deliveries, and stillbirths. Diagnosis of Q fever relies on serologic tests, polymerase chain reaction (PCR) analysis of whole blood or serum, and examination of tissue by culture or immunohistochemistry (IHC).
CDC researchers have produced two different monoclonal antibodies in mice, one specific for Phase I and the other specific to Phase II variants of C. burnetii. Both antibodies can detect the bacterium fixed on slides, making them extremely useful for pathogen detection through immunohistochemistry, a laboratory method that uses antibodies to check for certain antigens (markers) in tissue samples. These antibodies can also be used for other diagnostic assays, a companion diagnostic, and research tools.
- Diagnostic tests to confirm C. burnetii in human and veterinary samples
- Immunohistochemistry assays
- Companion diagnostic
- Public health monitoring, surveillance, and outbreak investigations
- Quality control in clinical and diagnostic tests for Q fever
- Research tools
- Antibodies allow definitive detection and differentiation of different phase variants of the bacterium
- Potential for use in antibody arrays as a rapid screen for surveillance of pathogens or outbreak investigations
- Currently, there are no antibodies specific for C. burnetii available for purchase in the U.S. market