Evaluation of a Rapid Immunochromatographic test kit to the Gold Standard Fluorescent Antibody Test for Diagnosis of Rabies in Animals in Bhutan

Abstract Background Rabies kills approximately 59,000 people in the world each year worldwide. Rapid and accurate diagnosis of rabies is important for instituting rapid containment measures and for advising the exposed people for postexposure treatment. The application of a rapid diagnostic tests in the field can greatly enhance disease surveillance and diagnostic activities, especially in resource poor settings. A total of 179 brain tissue samples collected from different rabies suspect animal species (113 dogs, 50 cattle, 10 cats, 3 goats, 2 horses, and 1 bear) were selected and tested using both rapid immunochromatographic kit and the reference standard fluorescent antibody test (FAT). We evaluated the test sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of a rapid antigen detection test kit produced by BioNote, Inc. (Hwaseong-si, Korea) to a FAT for its fit-for-purpose for confirmation of clinical cases of rabies for early response, prevalence of infection (rabies surveillance), freedom for infection and eradication of rabies. ResultsAmong 179 samples examined in this study, there was a concordance in results by the rapid test and FAT in 115 positive samples and 54 negative samples. Test results were discordant in 10 samples which were positive by FAT, but negative (false negative) by rapid kit. The rapid test kit showed a sensitivity of 92% (95% CI: 85.9 – 95.6) and specificity of 100% (95% CI: 93.4 – 100) using FAT as the reference standard. The positive and negative predictive values were found to be 100% (95% CI:96.7 – 100) and 84.4% (95% CI: 73.6 – 91.3), respectively. Overall there was 94.4% (95% CI: 90 – 96.9) test agreement between rapid test and FAT (Kappa value = 0.874) with a positive percent agreement and negative percent agreement of 92 and 100%, respectively.Conclusions Our finding demonstrated that the rapid test kit (BioNote) can be used for confirming clinical case of rabies in animals for making rapid decisions including early medical intervention in human exposure and controlling rabies outbreaks in resource poor settings. Keywords: rabies virus; diagnostic test; fluorescent antibody test; rapid anigen test; rapid immunochromatographic test; Bhutan