Baseline Widal Agglutination Titre in Apparently Healthy Nepalese Blood Donors

Abstract

Widal test could be the useful tool for the diagnosis of Typhoid fever, provided the results of Widal test are correctly interpreted. Interpretation of Widal test is based on the baseline titre of healthy population of particular geography. This study was carried out in view to determine Widal baseline titre of healthy blood donors in Nepal from June to December 2009, in Nepal Red Cross Central Blood Transfusion Service and Department of Microbiology of National College. Blood samples were collected from 490 apparently healthy blood donors from 5 different developmental regions. Widal agglutination titre was determined with the use of standard technique as per the manufacture’s instruction. Of the total 490 blood samples, 35.1% (172) samples showed anti O titre ≥ 1:20 against serotype Typhi, similarly 32.9% and 24.1% samples had titre ≥ 1:40 and ≥ 1:80 respectively. About 10.4% population had anti-O titre ≥ 1: 160. Of the total blood samples, 29.4% (143) samples showed anti H titres ≥ 1:20 against serotype Typhi, similarly 26.1% had a titre ≥ 1:40, and 16.3% had a titre ≥ 1:160. Anti-H titres ≥ 1:20 were found in serotype Paratyphi A (6.3%) and Paratyphi B (3.1%). Both ‘O’ and ‘H’ agglutination titre varied according to the geographical location. This study showed high titres >1:160 for serotype Typhi, ‘O’(10%) and ‘H’ (16.3%) of widal agglutinin in apparently healthy individuals. This necessitates larger rise in widal agglutinin titre for a ‘positive’ diagnosis. Widal test had played a major role in the diagnosis of typhoid fever in the past, but its diagnostic significance is less now.

Keyword: Widal test, Enteric fever, Nepal