Validity of TUBEX Test versus Widal Test in Detection of Typhoid Fever in Zagazig, Egypt

Abstract

Background and study aim: Typhoid fever is considered an endemic disease in Egypt. Widal test has been used for many years for diagnosing typhoid fever in the developing countries but it has serious doubts regarding its validity. TUBEX test is a simple rapid serodiagnostic test which has the advantages of Widal test without its controversy and it specifically detects the antibodies against S. typhi O9 lipopoly-saccharide antigen.The aim of this study is to estimate the validity of TUBEX test, its sensitivity and specificity, as compared to Widal test. Patients and methods: The study included 123 patients who presented with fever (≥3 days duration and temperature ≥38°C). Stool culture, Widal test, and TUBEX test were performed in all patients. TUBEX and Widal tests were compared as regard sensitivity and specificity in detection of typhoid fever using stool culture as a reference test. Results: 40 out of 123 febrile patients had positive stool culture and considered to have typhoid fever. Among them, Widal test was positive in 34 patients, giving a sensitivity of 85%, specificity of 88%, positive predictive value of 77.3% and negative predictive value of 92.4% while TUBEX test was positive in 38 patients with sensitivity, specificity, positive predictive value and negative predictive value of 95%, 90.4%, 82.6% and 97.4% respectively. Both tests showed a high statistically significant agreement with stool culture. Conclusion: TUBEX test shows higher sensitivity and specificity than Widal test. It is a simple test that gives rapid diagnosis for typhoid fever and can be useful in areas where facilities for culture are not available.