Diagnostic Accuracy of Rapid Antibody Detection Test for Scrub Typhus

ABSTRACT

Objectives: To detect the diagnostic accuracy of rapid antibody detection test using IgM immunochromatography for scrub typhus in children. Methods: This cross-sectional study enrolled children aged 2 months-18 years hospitalized over a period of 18 months with undifferentiated fever of duration five days or more. The blood samples were subjected to serological tests like Weil-Felix, Scrub IgM ELISA, immunofluroscence assay (IFA) and rapid diagnostic test (IgM Immunochromatography). Diagnostic accuracy was measured against IFA as the gold standard. Results: A total of 90 children were included in the study, among which 43 children were positive for gold standard test IFA. Rapid diagnostic test showed sensitivity of 88.3%, specificity of 89.3%, positive predictive value of 88.3% and negative predictive value of 89.3%. The sensitivity, specificity, PPV and NPV of Weil-Felix test was 39.5%, 84.2%, 58.6 and 71.1%, respectively and of IgM ELISA was 93%, 89.3%,88.8% and 93.3%, respectively. Conclusion: IgM immunochromatography had good diagnostic accuracy for scrub typhus in children with acute undifferentiated fever.