Q - fever (Coxiella Burnetii) IgG ||F

General information:

Essentially Q fever is a systemic infection that primarily affects the lungs. It is caused by Coxiella burnetii. When isolated from animals, C. burnetii -antigenic phase I variant (giant cell variant) is highly infectious and indicative of chronic infection. In the phase II form (small cell variant), C. burnetii is found in acute infection. In this phase, it is less infectious, but its life cycle is similar to spores, which ensures extracellular survival. The most common animal reservoir of zoonosis is cattle, sheep and goats. From infected animals, the causative agent is excreted through urine, feces, milk and amniotic fluid. In animals, the infection is asymptomatic. People become infected through inhalation of contaminated aerosols, raw milk and food.

Research methods

Q fever is a highly contagious disease, and for this reason isolation of the causative agent is allowed only in reference laboratories. Although the causative agent can be proven by molecular biological methods, serological diagnosis is much more convenient and applicable for this infection. Immunofluorescence methods are considered the most reliable and sensitive and are the reference for the diagnosis of both acute and chronic Q fever. Phase 1 and 2 assessment is possible for all three classes of antibodies, allowing the distinction between acute and chronic Q fever.

Screening tests:

• testing of IgM antibodies to Coxiella burnetii phase II using the chemiluminescence method (CLIA).
• testing of IgG class antibodies to Coxiella burnetii phase II by the chemiluminescence method (CLIA).

Confirmatory techniques and tests for staging infection

• examination of specific IgG class antibodies (phase I and phase II) to Coxiella burnetii by the indirect immunofluorescence (IIF) method.
• examination of specific IgM class antibodies (phase I and phase II) to Coxiella burnetii by the indirect immunofluorescence (IIF) method.
• examination of specific IgA class antibodies (phase I and phase II) to Coxiella burnetii by the indirect immunofluorescence (IIF) method.

Clinical manifestations of C.burnetii infection:

Fever, Atypical pneumonia, Granulomatous hepatitis, Endocarditis, Neurological manifestations (encephalitis, meningoencephalitis), Osteomyelitis.

• The chronic form of the infection occurs in about 5% of those infected. The process is considered chronic when it lasts more than six months after the onset of the disease. Clinical symptoms are associated with the development of a cell-mediated inflammatory response by the macroorganism. The cardiovascular system is mainly affected - clinically manifested as endocarditis, damage to the valvular apparatus and thromboembolism. Less often, the liver is affected with the development of chronic hepatitis and cirrhosis, or the musculoskeletal system with the development of osteomyelitis and osteoarthritis.

It is recommended that, in addition to the specific immunological test to prove the relevant clinical form of Q fever, the following should also be examined:

• CBC with ESR - in about 25% of cases, leukocytosis with accelerated ESR is observed, and in 30% - thrombocytopenia.
  
• Liver transaminases - AST, ALT, GGT - are increased in almost 90% of cases, and it is moderately 2 to 10 times above the norm.
• In chronic form of Q fever - autoantibodies - rheumatoid factor, antismooth muscle antibodies and antinuclear antibodies are often positive.

Sample required:

Venous blood

Key words:

q-fever, coxiella burnetii