EASTERN EQUINE ENCEPHALITIS - DISTRIBUTION OF CENTRAL NERVOUS SYSTEM LESIONS IN MAN AND RHESUS MONKEY

Brain and spinal cord were examined from a fatal human case of Eastern equine encephalitis, proved by isolation of virus from brain. Lesions were mild to moderate in the forebrain and brainstem, and were remarkably mild in the spinal cord. Rhesus monkeys were inoculated intracerebrally with unpassed virus from the fatal case, and with two unpassed mosquito isolates. All animals developed an acutely fatal encephalitis, with most severe lesions in the forebrain and mild lesions of the cord. Data from a previous study indicated that the distribution of lesions in the monkey CNS, following intracerebral inoculation of Langat and Japanese encephalitis viruses, both virulent group B arboviruses, was quite different than that produced by EEE virus, and was characteristic for each strain inoculated. These observations suggest that wild strains of EEE virus have very high primate neurovirulence regardless of the host in which they are multiplying in nature; and that in primates EEE virus has an innate tendency to produce severe lesions in the forebrain, with a relative sparing of the spinal cord. © 1968.