Evaluation for Immunochromatographic Test Method for Rapid Diagnosis of Typhoid Fever, Jimma, Ethiopia.

Abstract

Introduction:Even thoughdelayed results and the technical complexity makes difficult to routine laboratory practices, Culture remains to be the gold standard in the diagnosis of typhoid fever. Serological methods based on detection of antibodies like the Widal test are unreliable owing to their poor sensitivity and specificity. A reliable and affordable alternative rapid test methods is therefore needed in the diagnosis of typhoid fever. Objective: The aim of this study was to evaluate the reliability of a Rapid Immunochromatographic test method against blood and stool cultures in the diagnosis of typhoid fever in Jimma. Methods: ACross-sectional study was carried out on serum, blood and stool specimens were collected from a total of 275 febrile patients clinically suspected for having typhoid fever. The performances of a Rapid Immunochromatographic test method and the Widal test were evaluated in terms of sensitivity, specificity, positive and negative predictive values against culture as a gold standard. Drug susceptibility pattern were also done for Salmonella isolate. Analysis was carried out using SPSS version 20.0. Kappa test was used to assess the agreement between the tests.Result: Out of 275 Typhoid suspected cases which participated in the study, 172(62.5%) were males. Among the examined cases, 35(12.7%), 46 (16.7%) and 66(24.0%) were positive for culture, rapid and widal tests, respectively. The sensitivity, specificity, PPV and NPV of rapid test were 83.0%, 92.9%, 63.0% and 97.4%, respectively while that of Widal test were 68.6%, 82.5%, 36.4%, and 94.7% respectively. The Rapid immunochromatographic test showed a very good agreement (kappa= 0.668) but the Widal test was in a fair agreement with culture test (kappa = 0.371). Salmonella species were 100% resistant to Ampicillin and 40.0%, 17. %, 8.6%, 5.7% to Chloramphenicol, Cotrimoxazole, Nalidixic acid, Ceftriaxone and Norfloxacin, respectively. Conclusion: Rapid Typhoid IgG/IgM immunochromatographic test has better sensitivity, specificity and predictive values and has showed very good agreement with culture result as oppose to Widal test