Q fever antibodies - serum

Last updated: Sunday, 28, May, 2006

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Item Process
Specimen

Specimen: 5-10 mL blood in plain tube at onset and 2-3 weeks after onset of illness.

The request form should indicate the purpose of the testing (eg, pre-vaccination screening, possible acute infection or chronic Q fever infection, since different tests are used for each of these).

Method

CFT, IFA, EIA.

Application

Diagnosis of suspected Q fever, atypical pneumonia, hepatitis of unknown cause or blood culture-negative endocarditis.

Occupational health screening of abattoir and livestock workers at commencement of employment or after vaccination.

If chronic Q fever is suspected (eg, endocarditis) antibodies to phase I antigen should be specifically requested.

Interpretation

Infection with Coxiella burnetii stimulates antibodies to both phase I and phase II antigens.

In acute Q fever, antibodies to phase II antigen are detectable 1-2 weeks after onset of the illness and peak between 4 and 12 weeks.

Recent infection is confirmed by a four fold rise in titre or a positive IgM test. A single CFT titre of >8 for antibodies to phase II antigen indicates past infection.

Antibodies to phase I antigen are only present in significant titre in chronic Q fever (eg, endocarditis or granulomatous liver disease).

Reference

Maurin M and Raoult D. Clin Microbiol Rev 1999; 12: 518-553.

Field PR et al. J Clin Microbiol 2002; 40: 3526-3529.