Diagnosis of animal rabies: comparison of direct fluorescence test (dFAT), reverse transcriptase pcr and real-time PCR

Abstract

Rabies is endemic in most parts of India, with the exception of Andaman and Nicobar, Lakshadweep islands and to some extent Nagaland. For prevention and control it is essential to rapidly and precisely diagnose rabies. In this study, we used three diagnostic methods, direct fluorescent antibody test (dFAT), reverse transcriptase polymerase chain reaction (RT-PCR) and real time reverse transcriptase polymerase chain reaction (RT-qPCR) to detect the rabies virus in suspected animal brains. Out of the 80 animal brain samples tested, 64 (80%) were positive for rabies according to the RT-qPCR. Compared to the RT-qPCR, the sensitivities of dFAT and RT-PCR were 95.31% and 96.88%, respectively. The specificities of dFAT and RT-PCR were on far with qRT-PCR. Even though the dFAT findings did not completely coincide with results obtained from RT-PCR and RT-qPCR, dFAT appears to be a fast and reliable assay that can be used to analyze fresh brain samples. But in countries like India where temperature reaches 50°C during summer and lack of diagnostic facilities and trained personnel to carry out the dFAT at field level, the suspected samples will be usually sent to National/Regional Disease Diagnostic Laboratory /State veterinary or agricultural universities for rabies diagnosis. In summary the molecular methods RT-PCR and RT-qPCR can serve as quick and rapid diagnostic methods for animal rabies in India.