Systematic Veterinary Virology

LESIONS

• The most important lesions in rabies is encephalomyelitis (inflammation) in brain tissue and meninges with mononuclear infiltration, perivascular cuffing of lymphocytes or polymorphonuclear cells, Babes nodules consisting of glial cells and Negri bodies.
• Negri bodies appear as round or oval inclusions within the cytoplasm of nerve cells of animals infected with rabies. Negri bodies may vary in size from 0.25 to 27 µm. They are found most frequently in the pyramidal cells of Ammon's horn, and the Purkinje cells of the cerebellum. They are also found in the cells of the medulla and various other ganglia. Negri bodies can also be found in the neurons of the salivary glands, tongue, or other organs.
• Staining with Mann's, giemsa, or Sellers stains can permit differentiation of rabies inclusions from other intracellular inclusions. With these stains, Negri bodies appear magenta in color and have small (0.2 µm to 0.5 µm), dark-blue interior basophilic granules.