Comparison of Slide Widal with Tube Widal Agglutination Test for the Diagnosis of Enteric Fever in Febrile Patients

Enteric fever is a major public health problem with significant morbidity and mortality in India. The slide Widal agglutination test is a commonly used as rapid screening test however the diagnostic ability in comparison to the tube Widal agglutination test is low. The aim of this study was to compare the efficacy of the slide Widal and tube Widal agglutination test for the diagnosis of enteric fever. Two hundred and two individuals suspected to have enteric fever were enrolled for the study. Blood samples were collected aseptically, tested for the presence of anti O and anti H agglutinins against Salmonella typhi and S. paratyphi A and B by semi quantitative slide and quantitative tube agglutination tests. The titers taken as significant were 1: 80 and 1: 160 for O and H agglutinins respectively. Slide Widal agglutination test was positive in 50(24.8%) samples, of 50 slide agglutination positive samples only 28(56%) samples were positive by tube Widal agglutination test. Out of 152 slide agglutination negative samples, 2(6.6%) samples showed positive result by tube agglutination test. The slide agglutination test had a sensitivity of 93.3%, specificity of 87.2% as compared to Widal tube agglutination test. Due to high false positivity shown by slide agglutination test, it is suggested that serological diagnosis should not be made solely on the basis of slide agglutination test rather its results should be confirmed by using Widal tube agglutination test.