The theory of environmental factors is another possible explanation of this disease. Some believe that the disease lies dormant in the victim’s body until some environmental factor triggers it. Catching the common herpes virus or the measles can trigger Multiple Sclerosis. Around 400,000 people across the United States have been diagnosed with MS, and about 2.5 million people worldwide have been diagnosed. These numbers are an estimate by experts in the field because there is no registry for this disease. The average age of clinical onset is between 30-33 years old. However the average age for actual diagnosis is 37 years old. Only 10% cases are diagnosed after the age of 50 years old.
In the primary-progressive type of MS the numbers are close to equal between men and women being diagnosed. However, women are three times more likely to develop relapsing multiple sclerosis. People who live further away from the equator are more likely to be diagnosed with multiple sclerosis at some point in their life. Populations exposed to more amounts of ultraviolet radiation or sunshine had lower rates of multiple sclerosis. Caucasians are more susceptible to developing MS than those with African heritage. Those of African background tend to be older when diagnosed, but show more symptoms and signs. However, when they are diagnosed they show more signs of Opticospinal MS, which is multiple sclerosis in the spinal cord and optic