Determination of Baseline Widal Titres Amongst Apparently Healthy Blood Donors in Ahmednagar, Maharashtra, India

Abstract

Enteric fever is endemic in all parts of India. The Widal agglutination test is widely used for its diagnosis. But the interpretation of Widal test depends upon the baseline titre which is prevalent amongst healthy individuals in a particular geographical area. Present study was undertaken to establish the normal baseline titre in apparently healthy blood donors and also to determine cutoff values for the Widal test. One hundred and three (103) sera were tested by the Widal tube agglutination test from January 2012 to February 2013. Eighty four (81.55%) sera were positive for agglutinins (titre ≥ 1:20) and the remaining 19 were negative. 31.64% sera were positive for agglutinins of 'O' antigen of Salmonella typhi (TO) at a titre of 1:40, 33.87% sera were positive for 'H' antigen of Salmonella typhi (TH) at a titre of 1:40 and 38.46% and 36.84% sera were positive for 'H' antigen of Salmonella paratyphi A (AH) and Salmonella paratyphi B (BH) respectively, both at a titre of 1:80. Therefore, the baseline titre for TO and TH was noted to be 1:40 and that for AH and BH was noted to be 1:80 and therefore, the cutoff level for TO and TH was ≥ 1:80 and that for AH and BH was ≥ 1:160.