Comparative evaluation of immunofluorescence in different anatomical sites of brain in canine rabies by direct fluorescent antibody test

Rabies is an acute fatal encephalitis known to mankind ever since the dawn of human civilization. Dogs act as the principal vector for transmission of rabies in India. Direct fluorescent antibody test on brain sample is the gold standard test recommended for diagnosis of rabies. The present study was designed to compare immunofluorescence for rabies in different anatomical sites of brain by employing direct fluorescent antibody test (DFAT). Impression smears from cerebrum, cerebellum, hippocampus and brainstem of 30 rabies positive dogs were subjected to grading and comparative evaluation of immunofluorescence upon DFAT. The impression smears from these sites were subsequently graded from 1+ to 4+ based on intensity and distribution of fluorescence. The results revealed that brainstem and cerebellum showed almost similar and higher grades of fluorescence followed by hippocampus and cerebrum. The study also unveiled unilateral distribution of viral antigen in the hippocampus in certain cases which questions the reliability of employing hippocampal smears for DFAT. The study concluded that brainstem and cerebellum are the preferred samples for DFAT for rabies in canines.