Diagnosis of Q Fever

Abstract

My colleagues and I compliment Dr. Fournier and coauthors on an excellent review (3). However, we were surprised to read the statement that there is no commercially available enzyme-linked immunosorbent assay (ELISA) for the serological detection of Q fever, since papers describing these assays have been published (1, 2, 4). These ELISAs, for the detection of specific immunoglobulin M (IgM), IgA, and IgG antibodies produced during Q fever, are available from PanBio Pty Ltd., Brisbane, Australia. All tests use a common assay method, including the provision of cutoff control sera, and take less than an hour to perform. The availability of these tests in part contradicts the claim made by Fournier et al. (3) that ELISA is a more laborious technique than immunofluorescence assay (IFA) and requires considerable experience in interpreting the results. The IgG ELISA has been shown to have good correlation with immunofluorescence, and all patients determined to have a significant level of antibody by IFA were positive in the PanBio test (2, 4). The IgM and IgA ELISAs showed a significant correlation with the complement fixation test, with sensitivity of 100% and specificity of 89% being reported for each assay (1).