# Comparison of Diagnostic Accuracy in Enteric Fever: The Widal Test, Advantage Typhi, and Typhiwell IgM ELISA Against the Gold Standard Blood Culture

## TL;DR

This study compares three tests for diagnosing enteric fever and finds that the Typhiwell IgM ELISA is more accurate than the others, though blood culture remains the gold standard.

## Contribution

The study provides a direct comparison of diagnostic accuracy of Widal test, Advantage Typhi, and Typhiwell IgM ELISA against blood culture for enteric fever.

## Key findings

- The Typhiwell IgM ELISA had the highest sensitivity (88.46%) and overall diagnostic accuracy (95.89%).
- The Widal test showed moderate sensitivity (70.18%) and specificity (74.22%).
- Advantage Typhi had low sensitivity (12.28%) despite moderate specificity (81.02%).

## Abstract

Introduction

Enteric fever remains a significant public health issue in developing countries, where timely and accurate diagnosis is crucial for appropriate therapy and infection control. This study aimed to evaluate the diagnostic performance of the Widal test and two rapid IgM-based assays (Advantage Typhi and Typhiwell IgM enzyme-linked immunosorbent assays (ELISA)) compared with blood culture, the gold standard.

Methods

A prospective study involving 410 clinical samples from patients with suspected enteric fever based on clinical findings was conducted between December 2015 and June 2017. Blood culture, the Widal test, and two rapid Salmonella IgM assays (Advantage Typhi and Typhiwell IgM ELISA) were performed. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy were calculated.

Results

The Widal test demonstrated a sensitivity of 70.18%, a specificity of 74.22%, a PPV of 30.53%, an NPV of 93.91%, and an overall diagnostic accuracy of 73.66%. Advantage Typhi exhibited low sensitivity (12.28%) with moderate specificity (81.02%). The Typhiwell IgM ELISA showed the greatest sensitivity (88.46%) and the highest NPV (97.50%), but had reduced specificity (47.37%), leading to the highest overall diagnostic accuracy (95.89%).

Conclusions

The Typhiwell IgM ELISA provides improved diagnostic accuracy and may function as a rapid and effective diagnostic method in endemic regions. However, it should be used as a complementary test rather than a substitute for blood cultures. Additional studies, including molecular methods, are recommended to further enhance overall diagnostic accuracy.