Abstract

DETERMINATION OF BASELINE TITRE OF WIDAL TEST AMONG HEALTHY POPULATION IN EASTERN PART OF INDIA

Dr.Mrinal Pal*, Dr.Ritabrata Mitra, Dr.Subinay Datta, Dr.Maloy Mondal

Abstract

Background: 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. Lack of proper knowledge of baseline titre of Widal test in different geographical areas can lead to over diagnosis of typhoid fever leading to mismanagement of patients. Aims: This study was undertaken to evaluate baseline titre of Widal test using quantitative tube Widal test, to determine the cut-off value for positive Widal test in this region, and to correlate the results obtained in quantitative tube Widal test with that of rapid semiquantitative slide Widal test. Material and Methods: Sera of 117 apparently healthy blood donors from February 2011 and September 2013 in Blood Bank and Department of Microbiology of Medical College, Kolkata were subjected to quantitative tube and semiquantitative slide Widal test to know the titre. Results: Highest titre obtained by tube Widal test for TO was 1:160, for TH - 1:320, for AH- 1:20, and for BH- 1:80. Tube Widal titres of ≤1:80 for TO and TH were seen in 113 (96.58%) and 109 (94.01%), TO and TH titres of ≥ 1:160 were seen in 4(3.42%) and 9 (7.69%) respectively. TH titre of 1:320 was seen in 1(0.85%) and no such high titre was reported in relation to TO. Highest titre obtained by semi-quantitative slide Widal for TO was 1:640, for TH- 1:320, for AH-1:40 and for BH- 1:160. Conclusion: We recommend that TO and TH titre of > 1:320 as diagnostic of typhoid fever and for AH and BH, titres of ≥1:40 and ≥1:160 should be considered diagnostic respectively in our region. Because of high expected false positivity rate of slide Widal test even at the higher cut-off titre of 1:640, single slide Widal test appears to have little value in the diagnosis of typhoid fever in this region.

Keywords: Baseline titre, Widal test, Enteric fever, Endemic region