Evaluation of the diagnostic accuracy of lateral flow devices as a tool to diagnose rabies in post-mortem animals

Implementation of lateral flow devices (LFDs) for rabies antigen detection is expected to improve surveillance through the efficient detection of rabid animals in resource-limited settings; however, the use of LFDs for diagnosis remains controversial because some commercially available kits show low sensitivity. Therefore, we compared the diagnostic efficacy of three LFDs (ADTEC, Bionote, and Elabscience kits) paralleled with the direct fluorescent antibody test (dFAT) using fresh samples and investigated the diagnostic accuracies. To do so, we evaluated rabies-suspected samples submitted to the Regional Animal Disease Diagnostic Laboratory III, Philippines. Furthermore, we conducted real-time RT-PCR and sequencing to measure the accuracy of field laboratory diagnosis. The total number of animals submitted during this study period was 184 cases, including negative control samples. Of these, 53.9% (84 cases) were positive in the dFAT. Dogs were the most common rabies-suspected animal (n = 135). The sensitivities of the ADTEC and Bionote kits were 0.88 (74 cases) and 0.95 (80 cases), respectively. The specificity of both kits was 1.00 (100 cases). Furthermore, the sensitivity and specificity of the ADTEC kit after directly homogenizing the samples in assay buffer without dilution in phosphate-buffered saline (ADTEC kit DM) were 0.94 (79 cases) and 1.00 (100 cases), respectively. By contrast, there were no positive results using the Elabscience kit among all dFAT-positive samples. The sensitivity and specificity of LFDs make these tests highly feasible if properly used. Therefore, LFD tests can be used to strengthen the surveillance of rabies-infected animals in endemic and resource-limited settings.
Author summary Implementation of lateral flow devices (LFDs) for rabies antigen detection is expected to improve surveillance through the efficient detection of rabid animals in resource-limited settings because they are not only accurate but rapid, user-friendly, and low-cost tools. Although LFDs may positively contribute to accurate data reporting, the use of LFDs for definitive diagnosis remains controversial because some LFDs showed inadequate ability. In this study, we evaluated the diagnostic accuracy of three LFDs (ADTEC, Bionote, and Elabscience kits) paralleled with the direct fluorescent antibody test (dFAT) and real-time RT-PCR using fresh samples and investigated discrepancies among these tests. Of these, half of the submitted samples were positive in the dFAT. The sensitivity and specificity of the simplified ADTEC method (ADTEC kit DM) and Bionote kits were comparable with those of dFAT, but no positive reactions were observed using the Elabscience kit. Despite controversial discussions regarding the use of LFDs, we demonstrated that the diagnostic accuracy of ADTEC and Bionote kits was satisfactory under regional diagnostic laboratory conditions. Our results support the potential of LFD tests for in-field diagnosis of rabies in endemic countries and the feasibility for practical use when they are properly used.