Nested RT-PCR for ante mortem diagnosis of rabies from body secretionexcretion of animals suspected for rabies

Abstract

Aim: The present study deals with molecular technique Nested RT-PCR for detection of rabies viral RNA from biological fluid samples (Saliva, Milk and Urine) collected from animal suspected for rabies and to compare the sensitivity of Nested RT-PCR applied for ante mortem diagnosis of rabies with conventional technique (immunofluorescence) applied on neural tissue. Molecular technique Materials and Methods: Nested RT-PCR was applied on 62 biological fluid specimens collected from rabies suspected animals. First round amplification with nested set of primers (RabN1 and RabN5) yielded 1477 bp product while amplification with second round primers (RabNfor and RabNrev) yielded 762 bp product. Sensitivity of the technique was compared in accordance with WHO recommended gold standard test viz. Immunofluorescence (FAT) applied on brain samples. Results: By Nested RT-PCR, viral RNA could be detected in 9/24 (37.50%) saliva samples, 2/17 (11.76%) milk samples and 6/21 (28.57%) urine samples. Confirmatory diagnosis by Immunofluorescence performed on brain sample revealed 18 true positive cases. Overall, Sensitivity of Nested RT-PCR technique employed on fluid samples was 69.23% when compared with immunofluorescence performed on brain samples. Conclusions: Early reliable ante mortem diagnosis of rabies can be obtained from biological fluid samples of animals suspected to be rabid when tested with Nested RT-PCR technique.

Incidence of human rabies following bite or exposure to laboratory confirmed rabid animals

“…27 Rabies virus was detected in 9/24 (37.50%) saliva samples, 2/17 (11.76%) milk samples and 6/21 (28.57%) urine samples. 28 In the present study, humans were exposed to confirmed rabies cattle and buffalo by consuming milk, touching and milking rabid cattle and buffalo, but no human suffered from rabies up to one year of exposure. Moreover, all persons exposed to rabid cattle/buffalo were vaccinated with recommended doses of anti-rabies vaccine.…”