The Baseline Widal Titre Among the Healthy Individuals of the Hilly Areas in the Garhwal Region of Uttarakhand, India

Abstract

Typhoid fever is endemic in all parts of India and the Widal test is widely used for its diagnosis. In the endemic areas, the healthy people may contain antibodies which are capable of reacting upto a variable titre in the Widal test, due to a past exposure, TAB vaccination and cross reacting antigens. Therefore it varies widely from place to place and is referred to as the baseline titre of that area. The aim of this study was to determine the average baseline titre of the apparently healthy population in the Garhwal region of Uttarakhand, India. Blood samples were collected from healthy volunteers over the period from February 2011 to January 2012 and they were analyzed for the presence of the Salmonella antibodies by carrying out the Widal tube agglutination test. Among the 2164 serum specimens which were tested, 922 (42.6%) sera were found to be positive for the Widal test and 1242 were negative. The most frequently recorded titre of the reactive sera was 1:40 for the anti-O antibodies and it was 1:80 for the anti-H antibodies and this was the baseline titre for this region. Based on the above results of our study, it has been recommended that the cut-off titre of 1:80 for the anti-O antibodies and of 1:160 for the anti-H antibodies may be considered as diagnostic for enteric fever in the Garhwal region of Uttarakhand, India.