Abstract
For over 50 years, viruses have been implicated in the eitology of multiple sclerosis (MS) (Johnson, 1994). This is based on a number of epidemiological, genetic and virological studies. The epidemiology of MS supports a geographic association with evidence of MS clustering (Martin and Gale, 1997). There is an increased incidence of MS in temperate climates (less in the tropics) and migration to and from high prevalence areas of the disease influences the likelihood of developing MS. An increased risk of MS has also been suggested in children exposed to infectious agents while in adults, MS disease exacerbations increase with viral infection (Johnson, 1994). A variety of animal models have been developed in which viruses can cause diseases with long incubation periods, a relapsing remitting course, and demyelination (Johnson, 1994; Dalgleish, 1997).