MS is a disease in which the immune system eats away at the protective coverings of the nerves.
MS is thought to affect more than 2.3 million people worldwide. While the disease is not contagious or directly inherited, epidemiologists have identified factors in the distribution of MS around the world that may eventually help determine what causes the disease. These factors include gender, genetics, age, geography and ethnic background. Research has demonstrated that MS is most common amongst Caucasians, however susceptibility rates are highest in African Americans. The incidence of a disease is the number of new cases occurring in a given period of time (usually a year) in a given population (usually 100,000). With the challenges inherent in promptly and correctly identifying people with MS, arriving at an accurate incidence figure has been virtually impossible.
The prevalence of MS is the number of people with MS at a particular point in time, in a particular place. No specific antigen has yet been identified in MS, leading some MS experts to conclude that MS cannot be classified as autoimmune.