Many people with MS ask if their disease was caused by a virus
or other infectious agent. Much research has focused on trying
to answer this question. Evidence Pointing to a Viral Cause for
MS It is tempting to speculate on a viral cause for MS for
several reasons: - Viruses are known to cause demyelinating
disease in animals and humans. Demyelination (destruction of
myelin, the fatty sheath the surrounds and insulates nerve
fibers in the central nervous system) causes nerve impulses to
be slowed or halted and produces the symptoms of MS. - Data from
epidemiological studies—those that analyze variations in
geographical, socioeconomic, genetic, and other factors—suggest
that exposure to an infectious agent may be involved in causing
MS. Some viruses are known to have a long latency period between
time of infection and appearance of clinical symptoms, as is
thought to be the case in MS. - Increased antibodies to many
different viruses have been found in the blood and cerebrospinal
fluid of people with MS. Howev