Immunohistochemistry, histopathology, quantitative morphometry of negri bodies in the brain of rabid animals

Direct Fluorescent Antibody Technique (dFAT) on brain impression smears and tissue sections are the routinely used techniques for the diagnosis of rabies in animals and humans. Total 38 rabies suspected cases were subjected for rabies antigen/Negri bodies detection by immunofluorescence (19), immunohistochemistry (18) and histopathology (16). Sensitivity of immunohistochemistry and histopathology in comparison to dFAT on brain tissue smears was found to be 94.74% and 84.21%, respectively. Hundred neurons per case from different sites were visualized for presence or absence of Negri bodies and number of Negri bodies was counted in each positive neuron. With IHC 58.83% neurons were found positive for Negri bodies in comparison to 47.94% with H & E. Average number of Negri bodies detected per neuron by IHC and histopathology was 2.71 and 1.94, respectively. It was concluded that IHC was a more efficient and precise technique for detecting rabies viral antigen/Negri bodies in paraffin embedded formalin fixed tissues from rabies suspected case than conventional H&E staining.