Typhoid Fever in Kuala Lumpur and a Comparative Evaluation of Two Commercial Diagnostic Kits for the Detection of Antibodies to Salmonella typhi

V Gopalakrishnan, WY Sekhar, EH Soo, RA Vinsent, S Devi
Correspondence: A/Prof Shamala Devi, shamala@ummc.edu.my

ABSTRACT
The aim of this study was to compare two commercial kits, the Typhidot and the PanBio ELISA with the present Widal test. Demographic data for all serodiagnosed cases for the years 1991-1998 were collected. From this data, 144 were selected as samples for comparative evaluation of the commercial kits. Fifty sera were culture positive for Salmonella typhi, 50 were culture negative but clinically diagnosed as typhoid fever and Widal positive and 44 were serodiagnosed as enteric of which 21 were culture positive for other Salmonella species, 20 were serodiagnosed for other febrile illnesses and three sera culture positive for other species of enterobacteriaceae. The specificity, sensitivity and efficiency of the tests were calculated with the positive culture for S. typhi as the gold standard. Sensitivity, specificity and efficiency of test for Typhidot and Typhidot M kits were 98%, 76.6% and 84.0% and PanBio ELISA were 78%, 80% and 79.9%. The two commercial kits evaluated were found to be less time consuming and easier to perform than Widal. The Typhidot M seems to be a practical alternative in the field and in small hospitals with lesser facilities.

Keywords: Salmonella typhi, ELISA, immunodot blot, Widal
Singapore Med J 2002; 43(7): 354-358