Evaluation of the Performance of Widal Slide Agglutination Test Compared to Blood Culture and Evaluation of Interferon Gamma Response in the Diagnosis of Typhoid Fever

Abstract

Typhoid fever remains a significant public health challenge in developing countries, including Nigeria. The Widal test, widely used for diagnosing typhoid fever due to its simplicity and quick turnaround time, has raised concerns regarding its specificity. This study aimed to evaluate the performance of the Widal test in comparison to blood culture and assess interferon gamma response among the study subjects. Blood samples were collected from 90 patients exhibiting fever and other symptoms suggestive of typhoid fever. The Widal slide agglutination test, automated blood culture, and interferon gamma concentrations were assessed using rapid antibody detection kits, BACTEC, and sandwich enzyme-linked immunosorbent assay (ELISA), respectively. Among the 90 samples tested, 63 (70%) were positive for anti-Typhi O antigen, and 42 (46.7%) were positive for anti-Typhi H antigen. Conversely, 18 (20%) of the blood samples showed non-S. Typhi culture positive results, while 72 (80%) yielded no bacterial growth. Importantly, none of the cases were positive for Salmonella Typhi in blood culture. Regarding interferon gamma, subjects with lower levels (≤15 pg/mL) had no bacterial isolates from their blood, while as interferon gamma concentrations increased, more subjects had non-S. Typhi bacteria isolated. This finding indicates a relationship between interferon gamma levels and bacteremia. The study demonstrated that the Widal serology test may yield erroneous results, as all samples tested negative for S. Typhi using gold-standard culture methods. Furthermore, interferon gamma concentration was statistically correlated with the isolation of non-S. Typhi in blood cultures, suggesting that interferon gamma could serve as a potential marker for developing an alternative screening test, possibly an interferon gamma-based detection system for typhoid fever. Further research is recommended to explore this possibility.