Typhidot IgM as a reliable and rapid diagnostic test for typhoid fever among children in a tertiary care hospital

Background: Typhoid fever still continues to be a major public health problem in Nepal. A clinical spectrum of typhoid varies widely. It causes significant complication as well as mortality. A simple, reliable, affordable and rapid diagnostic test has been a long felt need of the clinicians to prescribe specific medication, adopt prevention of the emergence of antibiotics resistance and overall reduce the disease burden in the community.Methods: The prospective descriptive study was performed in 125 children between 2 years to 15 years of age admitted to the Pediatrics Department from September 2017 to September 2018. Blood culture, Typhidot rapid IgM were performed. MEDCALC software was used to calculate 95% confidence interval for sensitivity, specificity, predictive value positive, predictive value negative and accuracy. Kappa test was used to determine the agreement between Typhidot IgM and blood culture methods.Results: The study consisted of 125 children with acute febrile illness for more than 3 days with clinical symptomatology, consistent with typhoid fever. The reliability of Typhidot IgM in relation with blood culture and the study lighten that sensitivity 92.3% (95% CI: 63.9, 99.8), specificity 49.1% (95% CI: 39.5, 58.7), PPV 17.4% (95% CI: 14.2, 21.1), NPV 98.2% (95% CI: 89.2, 99.7) and accuracy 53.6% (95% CI: 44.5, 62.6). The two methods i.e. Typhoid IgM and blood culture shows significant agreement with p value 0.004.Conclusions: The present study demonstrates that Typhidot IgM has all the attributes of an ideal screening test.

Comparative evaluation of two rapid Salmonella‑IgM tests and blood culture in the diagnosis of enteric fever.

Purpose: Enteric fever is a major public health problem in developing countries like India. An early and accurate diagnosis is necessary for a prompt and effective treatment. We have evaluated the diagnostic accuracy of two Rapid Salmonella‑IgM tests (Typhidot‑IgM and Enteroscreen‑IgM) as compared to blood culture in rapid and early diagnosis of enteric fever. Materials and Methods: A total of 2,699 patients’ serum samples were tested by Rapid Salmonella‑IgM tests and blood culture. Patients were divided into two groups. Test group—patients with enteric fever and blood culture positives for Salmonella Typhi; and three types of Controls, i.e. patients with non‑enteric fever illnesses, normal healthy controls and patients positive for S. Paratyphi‑ A. In addition to this we have also evaluated the significance of positive Salmonella‑IgM tests among blood culture‑negative cases. Results: The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the Typhidot‑IgM test and Enteroscreen‑IgM test considering blood culture as gold standard were 97.29% and 88.13%, 97.40% and 87.83%, 98.18% and 92.03%, 96.15% and 82.27%, respectively. Typhidot‑IgM test was found to be significantly more sensitive and specific as compared to Enteroscreen‑IgM. Among blood culture‑negative patients, Rapid Salmonella‑IgM tests detected 72.25% additional cases of enteric fever. Although the Rapid Salmonella‑IgM tests are meant to diagnose S. Typhi only, but these tests detect S. Paratyphi‑ A also. Thirty‑eight patients who were blood culture‑positive for S. Paratyphi‑ A were also positive by Rapid Salmonella‑IgM tests. Conclusion: Rapid Salmonella‑IgM tests offer an advantage of increased sensitivity, rapidity, early diagnosis and simplicity over blood culture.