GANGANNAGARI VIJAY KUMAR AND PARVANGADA MADAPPA BEENA
Abstract
Scrub typhus, a zoonotic disease is caused by a gram negative bacterium Orientia tsutsugamushi. It is transmitted through the bite of the larva of trombiculid mites. There are many tests available to diagnose scrub typhus with their own advantages and limitations. Weil-Felix test is commonly used in the diagnosis of scrub typhus in spite of its low sensitivity and specificity. This study was conducted to know the seroprevalence of Scrub typhus in Kolar and the surrounding area and to compare the Weil-Felix test which is a nonspecific test with Scrub typhus IgM ELISA for the diagnosis of scrub typhus. Weil-Felix and IgM ELISA were performed in suspected patients of scrub typhus using commercially available kits. Among 197 samples tested, 12 were positive by both Weil-Felix test and IgM ELISA. Forty three samples showed negative by Weil-Felix test, but positive by IgM ELISA. Twelve samples which were positive by Weil-Felix test were negative by ELISA. Sensitivity, specificity, positive and negative predictive values of Weil-Felix test was 75%, 79.9%, 16.2% and 98.4% respectively taking IgM ELISA as a standard reference. The Cohnââ¬â¢s Kappa measurement agreement between Scrub typhus IgM ELISA and Weil-Felix was k= 0.7208. The seroprevalence of scrub typhus in Kolar and the surrounding area was 28%, which indicates scrub typhus could be one of the causes for fever of unknown origin.