It is conceivable that multiple infectious agents trigger MS. Unfortunately, if MS is caused by multiple agents, it is unlikely that measures will be available in the short term to decrease MS risk (14). Another possibility is that classic MS is primarily caused by a known or as yet unidentified agent that has not yet been firmly linked to MS. In favor of the unitary hypothesis is the distinct worldwide distribution of MS, restricted age-specific incidence, the effect of migration on MS risk, the relatively low concordance rate in identical twins who share a remarkably close childhood environment and reports, albeit controversial, of clustering of MS or changes in incidence in different locales. If only one or a few agents are responsible for triggering MS, disease incidence may be alterable by development and deployment of appropriate vaccines or antibiotics (14).
Several infectious agents currently remain as viable candidate agents because they may be compatible with the unique worldwide distribution of MS, they induce demyelination in humans or animals, agent-specific antibodies are elevated in the serum or CSF of MS patients, or the agent has been identified in MS tissues (1,14). Measles, human coronavirus 226E, EBV, retroviruses, HHV-6, and Chlamydia pneumoniae have attracted interest in recent years in terms of known agents that commonly infect humans. Animal viruses that have attracted the most attention are JHM, a mouse coronavirus; Theiler's murine encephalomyelitis virus, a picomavirus of mice; and CDV, a morbilliform virus of dogs and carnivores.
Was this article helpful?