BACKGROUND: Early diagnosis of typhoid is important for reducing mortality. In the absence of a blood culture, the quantitative tube Widal test is the standard serological test used for the diagnosis of Salmonella typhi, but rapid test kits are largely used in Northern Ghana. Variations in the performance of rapid test kits have been noted in other studies. We compared the diagnostic performance of two rapid test kits to the quantitative Widal method. METHODS: This was a cross-sectional study conducted from April to May 2024 in the Northern Region of Ghana. Quantitative tube Widal and rapid diagnostic tests using two different rapid test kits were performed using plasma collected from suspected Salmonella typhi patients. RESULTS: Of the 154 participants, most were females, 84 (54.5%). The quantitative tube Widal method detected 14 (9.1%) and 5 (3.2%) positive results for Salmonella typhi O and H antibodies, respectively, whereas the rapid diagnostic test kit type-1(IgM/IgG) detected 101 (65.6%)/47 (30.5%) positive results, and the type-2(IgM/IgG) detected 117 (75.9%)/39 (25.3%) positive results. The diagnostic performance of RDT Type 1 (IgM/IgG) was: sensitivity (85.7%/80.0%), specificity (36.4%/71.1%), PPV (11.9%/8.5%), and NPV (96.2%/99.1%). On the other hand, the performance of RDT Type 2 (IgM/IgG) was: sensitivity (85.7%/40.0%), specificity (25.0%/75.2%), PPV (10.3%/5.1%) and NPV (94.6%/97.4%). CONCLUSION: We found both rapid diagnostic test kit types to have a sensitivity of 85.7% with a specificity below 38% for IgM. Both test kit types also had low positive predictive values below 12% with negative predictive values above 94% for both IgM and IgG, and therefore detected more false positives than true positives.
Awe et al. (Wed,) studied this question.