Coxiella burnetii
The test designed to detect Coxiella burnetii DNA in human biomaterial by real-time PCR.Category «Respiratory tract infections»
Coxiella burnetii
Coxiella burnetii is an intracellular microorganism that causes Q fever (from “query fever,” meaning fever of unknown origin). The disease is characterized by a wide range of clinical manifestations, a tendency toward chronicity, and involvement of multiple organs and systems, most commonly the cardiovascular system.
The main source and natural reservoir of C. burnetii are farm animals (small and large ruminants, pigs, horses), as well as domestic animals (cats, dogs) and wild mammals (rodents). Ticks also play an important role in maintaining circulation of the pathogen in nature.
Routes of transmission:
- Airborne (primary): inhalation of contaminated dust containing particles of dried animal excreta, wool, or bedding.
- Alimentary: consumption of raw milk and dairy products or insufficiently heat-treated meat from infected animals.
- Contact: entry of the pathogen through the conjunctiva or damaged skin during animal birthing, slaughter, skinning, handling wool, or working with infected laboratory materials.
- Vector-borne: through bites of infected ticks; rare in humans but important for environmental circulation.
- Vertical: transmission from mother to fetus is possible.
Coxiella burnetii has unique virulence factors that enable survival and replication within host phagocytes:
- Antigenic variability: characterized by phase variation of outer membrane lipopolysaccharide. Phase I represents highly virulent strains circulating in natural reservoirs and infected animals; Phase II arises after repeated laboratory passages and has reduced virulence. This variability promotes long-term persistence and immune evasion. Chronic infection is associated with a predominant immune response to Phase I antigens.
- Intracellular parasitism: unlike most intracellular pathogens, C. burnetii actively utilizes an acidic environment for replication, enabling survival within immune cells and reduced susceptibility to many antibiotics and antibodies.
- Formation of resistant cellular forms: the bacterium shows high resistance to desiccation, ultraviolet radiation, and some disinfectants, contributing to high infectivity and prolonged environmental persistence.
The incubation period of acute Q fever averages 2–3 weeks. The disease typically begins abruptly and presents with diverse symptoms. The most common presentation is a flu-like syndrome with high fever (up to 39–40 °C), severe headache, chills, myalgia, and arthralgia. A characteristic feature is sharp eye pain. Additional manifestations may include:
- Atypical pneumonia with dry cough and chest pain;
- Hepatitis with hepatosplenomegaly without jaundice;
- Neurological disorders such as meningoencephalitis.
Chronic Q fever develops in individuals with predisposing factors, including pregnancy, immunodeficiency, prosthetic heart valves, and vascular grafts. The most severe complication is infective endocarditis, usually affecting the aortic or mitral valve. Clinical manifestations may appear months or years after acute infection. Other chronic manifestations include chronic hepatitis, osteomyelitis, and infections of vascular prostheses and aneurysms.
Coxiella burnetii is particularly dangerous during pregnancy. Infection is often asymptomatic or presents with nonspecific symptoms but is associated with a high risk of adverse outcomes, including miscarriage, preterm birth, and fetal death. Vertical transmission and fetal infection are also possible.
Laboratory diagnosis of Q fever includes serological methods (ELISA, indirect immunofluorescence), culture (rarely used), and PCR.
Real-time PCR is a highly sensitive and specific method that allows detection of Coxiella burnetii DNA at early stages of disease and in chronic forms. Test materials may include nasopharyngeal and oropharyngeal swabs, bronchoalveolar lavage, endotracheal or nasopharyngeal aspirates, sputum, pleural fluid, cerebrospinal fluid, blood, biopsy specimens, and autopsy material.
Indications for the test
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Fever of unknown origin, especially when combined with atypical pneumonia or hepatitis; -
Suspected infective endocarditis with negative blood culture results on standard media; -
History of contact with farm animals; -
Epidemiological history (residence in or travel to endemic areas); -
Evaluation of immunocompromised patients or those with prosthetic heart valves or vascular grafts when infection is suspected; -
Investigation of causes of miscarriage, preterm birth, or intrauterine fetal death; -
Differential diagnosis with other rickettsioses, brucellosis, leptospirosis, and viral hepatitis.
Coxiella burnetii
The Coxiella burnetii REAL-TIME PCR Detection Kit is designed to detect DNA of Coxiella burnetii in human biological material by real-time PCR.
Sample: Nasopharyngeal, oropharyngeal swabs, bronchoalveolar lavage, endotracheal, nasopharyngeal aspirate, phlegm, pleural fluid, cerebrospinal fluid, blood, biopsy material, autopsy material
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