Endemic titres to Salmonella Typhi as determined by the Widal titres in a tertiary care centre in south Kerala

Background: In developing nations endemic to typhoid, laboratory diagnosis by blood cultures is still not considered an affordable option. In this context serological tests like the Widal test, are widely used andpreferred.1 In order to interpret Widal test on a single sample in endemic countries for diagnosis of typhoid fever, baseline titers need to be determined. These endemic titers change with time and require periodic revision. Methods: This is a cross-sectional observational study done in Department Microbiology, in a tertiary care center in south India. The sample size was 206 and comprised sera of consenting patients with no recent history of fever in past 3 weeks to represent apparently healthy population of a community. Widal tube agglutination test was done and endemic and significant cutoffs were determined. Results: Among the 206 non-febrile individuals included in the study, the majority (41.7%) were in the 41–60-year age group and males formed a higher proportion (57.3%) compared to females (42.7%). 95th percentile of O and H Antibody titres was 1:40, which can be considered the endemic baseline and titres, hence above the endemic titres (more than or equal to 80) can be considered as significant titres.