Diagnosis of rabies from brain: Comparison of histochemical and histopathological approaches

Accurate laboratory diagnosis of rabies can impact significantly on the reduction of rabies related deaths every year. Receiving fresh samples for authentic diagnosis in a laboratory is practically unfeasible in tropical countries and working with fresh brain samples renders increased chances of infection therefore, formalin fixed tissue samples offer better promise as a practically feasible approach for diagnostic investigation. Thus, present study was envisaged to compare the effectiveness of immunohistochemistry (IHC) and histopathology in comparison to gold standard fluorescent antibody test (FAT) in diagnosis of rabies from brain samples of 34 rabies suspected animals (13 dogs, 11 buffaloes, 8 cattle, 1 cat and 1 horse). Sensitivity and accuracy of histopathological demonstration of Negri bodies was found to be 83.33% and 88.88%. Sensitivity and accuracy of IHC in rabies diagnosis was found to be 100%, exhibiting good agreement to FAT. IHC provides a promising alternative approach to gold standard FAT where FAT is not feasible and it should always be preferred method of choice over histopathology technique.