EVIDENCE FOR MULTIPLE-SCLEROSIS AS AN INFECTIOUS-DISEASE

Evidence for a viral cause of multiple sclerosis (MS) is indirect sinc e no infectious agent has been reproducibly isolated from MS tissues n or has viral genome or antigen been consistently identified. The occur rence of spontaneous human and animal models of demyelination, serolog ic studies, and epidemiologic data provide pursuasive circumstantial e vidence for an infectious trigger in this disease. Potential mechanism s for viral induced demyelination include persistent infection of host tissues or immune mediated organ damage either in the presence or abs ence of the infectious agent. Any proposed viral candidate should caus e demyelination in animals or man and the pattern of infection should be consistent with the unique geographic features of MS epidemiology. In addition, serologic studies should support an infection by the agen t and:or viral genome should be detected in MS tissues. At this time n o virus can be unequivocally linked to MS but cumulative evidence is m ore supportive of canine distemper virus than other viruses.