Canine distemper virus and multiple sclerosis.

Abstract

One of many hypotheses in the literature addressing the etiology of multiple sclerosis (MS) proposes that exposure to canine distemper virus increases the risk of MS. Canine distemper virus is one of more than a dozen viruses that, at one time or another, have been thought to be involved in the etiology of MS. This review briefly summarizes the epidemiologic evidence for this relationship. Epidemiologic investigations of MS have reported marked geographic variation in MS prevalence, and it is now widely believed that MS is a disease with a long latency period following a critical event likely occurring during childhood or early adolescence.1 Studies of migrants between countries with differing prevalence indicate that people born in a high-prevalence area who move to a low-prevalence area develop MS at the same rate as the population of the host country if this move occurs prior to adolescence. If the move takes place after adolescence, the evidence indicates that individuals retain the risk of their native country.2 This evidence is quite convincing for migrants from high-prevalence to low-prevalence areas, but less so for the reverse pattern of migration from countries of low-prevalence moving to countries of high prevalence.1 These data suggest that one or more environmental exposures occurring before adolescence may pre-dispose to developing MS later in life. Since exposure to numerous viruses occurs during childhood, and since viruses are well recognized causes of demyelination and inflammatory responses, MS may have a viral etiology. Many authors have investigated infectious agents, with particular interest in viruses, including Epstein-Barr virus, varicella, and canine distemper virus.2,3 Canine distemper virus is a ubiquitous neurotropic virus causing canine distemper in the animal families Canidae (dog, fox, coyote, and wolf), Mustelidae (mink, otter, weasel, skunk, marten, fisher, and wolverine), and Procyonidae (raccoon) as well as …