CROSS-REACTIVITY AND SPECIFICITY: A COMPARATIVE ANALYSIS OF WIDAL AND TYPHI DOT IN ENTERIC FEVER DIAGNOSIS
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Keywords
Enteric fever, Typhoid fever, Widal test, Typhidot test, Cross-reactivity, Specificity, Serological diagnosis, Salmonella Typhi, Diagnostic accuracy
Abstract
This study aimed to conduct a comparative analysis of the Widal and Typhidot tests in the diagnosis of enteric fever, focusing on cross-reactivity and specificity. A prospective, cross-sectional study was conducted over 12 months, involving 216 patients with suspected enteric fever. Blood culture served as the gold standard for comparison. The Typhidot test demonstrated superior performance with higher sensitivity (86.2% vs 72.4%) and specificity (88.0% vs 83.5%) compared to the Widal test. ROC curve analysis confirmed the Typhidot's better overall diagnostic accuracy (AUC 0.87 vs 0.78). Cross-reactivity analysis revealed higher false-positive rates for the Widal test, particularly with non-typhoidal Salmonella (40%) and other Enterobacteriaceae (25%). The Typhidot test showed improved specificity with lower cross-reactivity. Multivariate analysis identified age <15 years and prior antibiotic use as significant factors influencing Widal test outcomes, while fever duration >7 days affected Typhidot results. Despite substantial agreement between the tests (Cohen's Kappa 0.68), discordant results highlighted the potential for misclassification when relying on a single test. While the Typhidot test demonstrated better overall performance, both tests showed limitations in cross-reactivity and specificity. These findings underscore the need for careful interpretation of serological test results in the context of clinical and epidemiological data. Future research should focus on developing more specific antigens, exploring combination approaches, and integrating host biomarkers to enhance enteric fever diagnosis in endemic settings.
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Nandlal Kumar
Tutor, Department of Microbiology, GMC, Bettiah, Bihar
Chandra Shekhar Jha
Assistant Professor, Department of Microbiology, GMC, Bettiah, Bihar
Vijay Kumar
Associate Professor, Department of Microbiology, GMC, Bettiah, Bihar
Animesh Kumar
Tutor, Department of Microbiology, GMC, Bettiah, Bihar