Multiple sclerosis (MS) is a disease caused by damage to the nerve fibers in the central nervous system (CNS), which disrupts the signals sent to and from the brain. MS is a progressive disease that worsens over time and eventually leads to death.
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What is MS?
MS is an autoimmune disease, which is a disease where the body’s immune system attacks healthy tissue within the body. In the case of MS, the immune system mistakes myelin, which is the protective covering that surrounds nerve fibers, for a foreign body and mounts an immune response against it.
Diseases that involve damage to this myelin are called demyelinating diseases. Destruction of the myelin disrupts the ability of the nerve to conduct signals, which may be slowed or stopped altogether.
Some experts believe a certain combination of genes may predispose an individual to MS, while other theories suggest that viral infection of the immune and/or nervous system may be responsible.
Research into the incidence of the condition across the globe has shown that MS is more common in countries that lie further north of the equator, such as the United Kingdom and Scandinavia than in countries such as Malaysia or Ecuador, for example. One theory that supports this is that a lack of sunlight and subsequently vitamin D plays a role in the development of MS.
Worldwide, the median estimated prevalence of MS is 30 per 100,000 population. Globally, the median incidence of new cases annually is 2.5 per 100,000 population. Among different regions, the median estimated prevalence is highest in Europe, at 80 per 100,000 population. This is followed by a prevalence per 100,000 of 14.9 in Eastern Mediterranean regions, 8.3 in the Americas, 5.0 in the Western Paciﬁc, 2.8 in South East Asia, and 0.3 in Africa.
The highest estimated prevalence of MS by country is found in Hungary at 176 per 100,000 population, followed by a prevalence per 100,000 of 150 in Slovenia, 149 in Germany, 135 in the United States, 133 in Canada, 130 in the Czech Republic, 125 in Norway, 122 in Denmark, 120 in Poland, and 110 in Cyprus.
Studies have also shown that when countries are stratified by income, the median estimated prevalence of MS is greatest in the high-income countries, at 89 per 100,000 population. This is followed by an estimated prevalence of 32 per 100,000 in upper-middle-income countries; 10 per 100,000 in lower-middle-income countries; and 0.5 per 100,000 in low-income countries.
Overall, MS is more common among white populations than in non-white populations.