Comparison of immunofluorescence with enzyme immunoassay for detection of Q fever

To evaluate enzyme immunoassay (EIA) as an alternative to indirect immunofluorescence assay (IFA) to screen for Q fever in humans, 157 serum samples from patients suspected of having the disease were tested for immunoglobulin G antibodies to Coxiella burnetii. The agreement between the tests and the sensitivity of EIA were excellent (96.8% and 98.4%, respectively) when an IFA titer of > 1/160 was considered positive. All serum samples with a titer of > 1/320 in the IFA were also positive by the EIA. The EIA seems to be an acceptable alternative to IFA for screening for Q fever.