Comparison of PCR, Immunofluorescence Assay and Isolation Method for Diagnosis of Q fever in Humans with Spontaneous Abortions

Division of Veterinary Public Health, National Biotechnology Centre, Indian Veterinary Research Institute, Izatnagar 243 122 India, and ICAR Research Complex for Goa, Ela, Old Goa 403 402, India

^* To whom correspondence should be addressed. Email: drvilasmvaidya{at}rediffmail.com.

	Abstract

Coxiella burnetii, an obligate intracellular parasite with a worldwide distribution, is the causative agent of Q fever in humans. We tested a total of 368 samples (placental bits, genital swabs, faecal swabs, urine and serum samples) collected from women (74) with spontaneous abortions for C. burnetii by PCR assay targeting IS1111 the repetitive transposon-like region of C. burnetii (trans-PCR), real-time PCR, indirect immunofluorescence assay (IFA) and isolation of the pathogen. The IFA showed seropositivity in 25.68% women with spontaneous abortions, whereas, trans-PCR and real time PCR detected the pathogen in 21.62% cases each. Overall, 25.68% cases were positivity in one or more assays. Real-time PCR showed higher sensitivity than trans-PCR. In comparison to IFA, the highest sensitivity (84.21%) was shown by both PCR assays followed by isolation method (26.31%), while both the PCR assays and isolation method were specific (100%). The detection of high numbers of C. burnetii in clinical samples and frequent association of the pathogen with cases of spontaneous abortions observed in the study revealed that Q fever remains under diagnosed, and the prevalence is under estimated in this part of the world.