Page "Multiple sclerosis" Paragraph 18

Evidence for viruses as a cause includes the presence of oligoclonal bands in the brain and cerebrospinal fluid of most people with MS, the association of several viruses with human demyelination encephalomyelitis, and induction of demyelination in animals through viral infection.

Human herpes viruses are a candidate group of viruses linked to MS.

Individuals who have never been infected by the Epstein-Barr virus have a reduced risk of having the disease, and those infected as young adults have a greater risk than those who had it at a younger age.

Although some consider that this goes against the hygiene hypothesis, since the noninfected have probably experienced a more hygienic upbringing, others believe that there is no contradiction since it is a first encounter at a later moment with the causative virus that is the trigger for the disease.

Other diseases that have also been related with MS are measles, mumps, and rubella.