A comparative study of the performance of the widal slide agglutination test and the typhidot immunoassay for the diagnosis of typhoid fever in the West Region of Cameroon.

Abstract

Background: The diagnosis of Typhoid fever, based on the Widal slide agglutination test, remains a major hurdle in developing countries like Cameroon due to varied perceptions of the value of the Widal test in determining clinical decision making. We undertook a study to evaluate the diagnostic performance of the Widal test and the typhidot immunoassay in patients suspected of having typhoid fever in the Menoua division, West Region of Cameroon. Methods: Blood and stool samples were collected from 558 consenting febrile patients on the basis of suspicion of typhoid fever. These patients attended three district health services of the Menoua division between April 2018 and September 2019. These patients had clinical symptoms suggestive of typhoid fever as determined by their consultant. Serum from whole blood was used for the Widal slide agglutination test and for the Typhidot rapid immunoassay test based on manufacturer’s guidelines. A composite reference of fever plus positive coproculture for Salmonella enteric serovars typhi and paratyphi was used as reference. The sensitivity, specificity, predictive values of the positive and negative tests were calculated as well as the Cohen’s Kappa for agreement between the two tests. Results: Of 558 patients, 12.90% tested positive for the reference method, 57.17% tested positive for the Widal slide agglutination test while 15.59% were positive for typhidot-IgM. The overall sensitivity, specificity, predictive values of the positive and negative tests were 80.56%, 94.03%, 66.6% and 97.03% respectively for typhidot-IgM; 94.44%, 48.35%, 21.32% and 98.33% for Widal slide agglutination test. The Cohen’s kappa estimates were 0.1660 (0.121-0.211), 0.386 (0.312-0.460) for Widal test and typhidot immunoassay respectively, with agreements of 53.76% and 76.16% respectively. Conclusion: The Widal test was found to have a lower predictive value for the diagnosis of typhoid fever in our setting. However, the Typhidot test, although better, was not ideal. Diagnosis of typhoid fever should therefore rely on adequate clinical suspicion and a positive Typhidot test to improve the clinical management of Typhoid fever in our setting.