Human rabies encephalitis

Abstract

The files of the Armed Forces Institute of Pathology (1930-1064) were reviewed. Most fatal human cases occurred in young adult males, and nearly 1/4 were in children. Dog bites accounted for 51% of fatal cases; however, a large number yielded no history of animal exposure. Upper extremities, face, and lower extremities were bitten in decreasing order of frequency but had no bearing on the subsequent duration of the incubation period, which averaged 57.3 days. The mean clinical course ran 7.4 days. Neuritis, chills, and fever were the commonest prodromal symptoms, whereas psychiatric or pharyngeal manifestations became dominant in the fully developed clinical picture. The most frequent pathological finding was a combination of intracyto-plasmic rabies inclusions in neurons of the cerebellum and hippocampus and inflammation. The latter consisted of perivascular cuffs of lymphocytes and plasma cells, parenchymal microglial response, and, at times, neuronophagia. This type of inflammatory reaction usually occurred in the brainstem and spinal cord. Rabies encephalitis is predominantly a polioencephalomyelitis. Negri bodies were common in disease with a long total course, while inflammation appeared to be an early manifestation. Meningitis was observed in 3 children.