Comparative evaluation of clinicopathological, immunohistochemical, and immunofluorescent techniques for diagnosis of rabies in animals

摘要

Rabies is one of the most feared zoonotic diseases in the world. The present study was envisaged to compare the sensitivity of detection of rabies virus antigen by histopathological and immunohistochemical approaches in the brain tissues of 100 rabies-suspected animals. In dogs, anorexia, difficulty in standing/paralysis, and hypersalivation were the common clinical signs, whereas in cattle and buffaloes, important clinical signs of rabies were anorexia, circling/head pressing, behavioral change, and bellowing. Percentage of neurons positive for Negri bodies by hematoxylin and eosin (H&E) and immunohistochemistry (IHC) were 33.34 and 65.71 %, and average number of Negri bodies detected per neuron by H&E and IHC were 1.72 and 3.00, respectively. Out of total 100 samples, 60 were positive for rabies by IHC, 58 by fluorescent antibody technique (FAT), and 45 by histopathology. The sensitivity of histopathology and IHC on brain tissue sections in comparison to FAT of brain smears was found to be 64.28 and 100 %, respectively. The amount of rabies viral antigen/Negri bodies detected with IHC was significantly more than that detected by H&E. It was concluded that immunohistochemistry in formalin-fixed paraffin-embedded tissue sections was more sensitive than histopathology for the detection of Negri bodies/rabies antigen, and therefore of immense value for retrospective studies.