الفهرس 
Epidemiology and pathology of MSOnly 14 pages are availabe for public view
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Abstract
Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) and the most common cause of disability amongst young adults. The majority of patients present with a relapsing-remitting illness, characterized by discrete episodes of focal neurological deficit with temporal and anatomical dispersion in the CNS.
Chronic CNS infection (eg, with a virus or other agent), or an autoimmune process triggered by an infection, have each long been etiological hypotheses for MS. Various infectious models have been proposed to account either for the inflammatory pathology of the disease or to explain the geographic variability in disease incidence or prevalence based on latitude or migration patterns.
The hygiene hypothesis, in which exposure to infectious agents in early life protects against MS, suggests that MS is an autoimmune reaction that is triggered in susceptible individuals in response to infection by multiple microorganisms, with risk increasing with age at infection. This hypothesis could account for the latitude gradient, higher incidence rates among individuals with greater socioeconomic status, the trend toward a later age at infection with childhood viruses in MS cases than control subjects, and the lower risk for MS among individuals exposed to infant siblings in early life. It might also explain the diminishing latitude gradient within the United States if improved hygienic conditions were responsible for change in infection pattern.
Epstein-Barr virus infection is very common, affecting >95% of the general population by adulthood. It was noted that infectious mononucleosis, the common clinical expression of EBV infection in adolescence and early adulthood, follows.