Eastern equine encephalomyelitis. Histopathologic and ultrastructural changes with isolation of the virus in a human case.

Enveloped Toga virus particles were demonstrated by means of an electron microscopy in the brain tissues of a 3-year-old girl with acute encephalitis. Areas of demyelinization and necrosis throughout the white matter and brainstem were revealed by light microscopy. These viral particles were identified as eastern equine encephalomyelitis virus in postmortem isolation of the virus utilizing young mice and complement-fixation studies. To the authors' knowledge, this is the first demonstration of eastern equine encephalomyelitis virus particles in human tissues by electron microscopy.