TYPHOID FEVER

EVALUATION OF TYPHIDOT (IGM) IN EARLY AND RAPID DIAGNOSIS OF TYPHOID FEVER

Abstract

Background: Typhoid fever is widely recognized as a major public health problem in developing countries. A simple, reliable and rapid diagnostic test is needed for clinicians especially in areas where laboratory services are limited. Objective: To evaluate sensitivity and specificity of typhidot (IgM), a serological test to identify IgM antibodies against salmonella typhi. Study Design: This was a prospective study. Setting: Northern Institute of Medical Sciences (NIMS) and Ayub Teaching Hospital Abbottabad. Period: 1st November 2009 to 31st August 2010. Methods: A total of 100 patients with clinically suspected typhoid fever were studied and divided into three main groups as A, B and C, with definite typhoid fever, typhoid suspects plus non-typhoidal illnesses and healthy controls respectively. Blood culture and typhidot (IgM) tests were conducted for all subjects included in the study. The validity of typhidot (IgM) test has been evaluated by determining the sensitivity, specificity, positive and negative predictive values. Results: In our study, majority (75%) were males and (25%) females with M to F ratio of 3:1. The mean age of study group was 26.31±11.8 (SD) years. Among 100 clinically diagnosed typhoid fever patients, 19 had positive blood culture for S.typhi and 71 were typhidot (IgM) positive. Out of 19 culture positive patients, 18 (94.73%) were true typhidot (IgM) positive, which was also falsely positive in 05 (20.83%) among 24 non- typhoidal febrile controls. None of the healthy controls was positive for typhoid (IgM) test. The sensitivity, specificity, negative and positive predictive values of typhidot (IgM) test using blood culture as gold standard were 94.73%, 90%, 97.72% and 78.26% respectively for patients having typhoid fever. Conclusions: Typhidot (IgM) test is a simple, reliable, rapid and valid diagnostic tool for typhoid fever especially in areas where laboratory services are limited.