Epidemiology of multiple sclerosis

Multiple sclerosis (MS) refers to a family of diseases characterized by idiopathic inflammatory demyelination of the CNS. In most areas, MS appears to be increasing in prevalence and incidence, although improved ascertainment renders this observation difficult to interpret. Both environmental and genetic factors contribute to cause MS. Ecologic and correlational studies have been used to identify causal factors operative on a population level, whereas case-control studies have been applied to identify factors affecting individual risk. To date, no single causal agent has been associated convincingly with MS, with the possible exception of the class II major histocompatibility haplotype DR2-DQ6.