Diagnosis of Acute Q Fever by Detection of

introductionQuery (Q) fever is an important zoonosis and a cause of concern for humans, due to the potential bioterrorism threat posed by the causative agent,

aimTo study the prevalence of acute Q fever in Puducherry and surrounding districts of Tamil Nadu, India, employing a new commercial Real-Time Polymerase Chain Reaction (RT-PCR) kit and confirming it by the gold standard Immunofluorescence Assay (IFA). MATERIALS AND

methodsAcute phase blood samples from 72 consecutive febrile patients and 24 healthy individuals were included in this prospective study. DNA was extracted from the buffy coats and preserved at -80°C. Detection of

resultsPresumptive diagnosis of acute Q fever was made in two febrile patients by the Genesig Easy kit (2.78%). In addition to these two PCR positive cases, one more patient was positive for both Phase II IgM and Phase II IgG antibodies by the gold standard IFA. All 24 healthy controls were negative for Q fever by both PCR and IFA. The sensitivity, specificity, NPV and PPV for Genesig Easy kit PCR were: 66.67%, 100%, 100% and 98.57 % respectively against IFA as the reference.

conclusionThe true prevalence of Q fever in India and other developing countries is poorly understood, owing to the difficulties in the diagnosis of this infection. Since molecular diagnostic tests have good specificity and are mandated for confirmation of single acute samples, validation of commercial Q fever PCR kits is the need of the hour. Genesig Easy kit in our hands was found to be reliable with the moderate sensitivity and high specificity. Performing both PCR (with acute specimens) and IFA (with paired sera) would be ideal for Q fever diagnosis.