Which histologic findings are characteristic of rabies?

Updated: Jun 21, 2019
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

General findings on pathology include cerebral congestion and inflammation typical of encephalitis. Neuronal cell death is uncommon histopathologically.

Immunohistochemical or fluorescent antibody staining of nervous tissue, usually of unfixed brain or skin biopsy specimens with sensory nerve endings, reveals deposition of virion in the cytoplasm.

Negri bodies, seen in the image below, are observed in neurons on light microscopy and represent round cytoplasmic inclusions of assembling nucleocapsid. Only 70% of brain biopsy tissue exhibits this finding in human rabies encephalitis. Electron microscopy is more sensitive than light microscopy and reveals the characteristic bullet-shaped virion.

Hematoxylin and eosin stain of Negri body in a rab Hematoxylin and eosin stain of Negri body in a rabies-infected neuron. Courtesy of the US Centers for Disease Control and Prevention.

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