Typhidot - A blessing or a menace

Typhoid remain an increasing problem in Third world countries like Pakistan. A reliable, easy and affordable rapid diagnostic test is a need for our clinicians, many of whom consider Typhidot to be promising. Typhidot has been used as the only tool to diagnose typhoid fever by general practitioners and consultants despite its low sensitivity and specificity causing misdiagnosis and treatment. We therefore conducted this study to evaluate the sensitivity and specificity of Typhidot in patients with fever.

A retrospective analysis of a total of 145 febrile patients was done. Blood culture and Typhidot along with other relevant investigations had been performed in each case. Sensitivity, specificity and the association of Typhidot to the diagnosis was found using SPSS v16.0.

Out of 145 patients, 15(10.3%) had positive blood culture for Salmonella typhi, 7 (4.8%) had positive culture for salmonella paratyphi and 94(64.8%) had positive culture for other organisms. Twenty nine (20%) patients had negative culture results. Forty seven (32.4%) patients had only IgM positive on Typhidot, 7(4.8%) had both IgM and IgG positive and 91(62.8%) had both IgM and IgG negative. Amongst the 130 patients with diseases other than typhoid, 50(38.5%) showed a positive Typhidot result. Amongst the 15 patients with typhoid, 11(73.3%) showed a negative Typhidot result. The sensitivity of Typhidot was found to be 26.7% and the specificity was 61.5%. The Positive Predictive Value (PPV) was 7.4% and the Negative Predictive Value (NPV) was 87.9%.

Even though Typhidot is rapid, easy and affordable, its use should be discouraged due to low sensitivity and specificity and insignificant (p=0.067) association to the disease.