As viruses go, Epstein-Barr [EPP-stine BARR] is a wolf in sheep’s clothing.

One of the most common human viruses, it’s believed to strike up to ninety-five percent of all Americans by the time they reach middle age.

People infected during childhood may hardly notice the virus’ effects. But in young adults, it causes mononucleosis.

There’s an even more serious condition associated with Epstein-Barr multiple sclerosis, a mysterious disease that attacks nerve fibers.

Patients may experience fatigue, numbness, loss of coordination, even paralysis.

Scientists already know exposure to Epstein-Barr may increase the risk of developing multiple sclerosis. But a new study indicates the virus’ influence may last twenty years.

As reported in a recent issue of Archives of Neurology, researchers examined patient records kept by a California health plan. They looked for patients with multiple sclerosis who gave blood samples before the disease appeared.

Forty-two patients met those criteria. Many had unusually high levels of antibodies against Epstein-Barr.

By comparing those patients with people who didn’t have multiple sclerosis, researchers determined that a fourfold increase in antibodies doubled the risk of contracting the disease.

Some patients had elevated levels of Epstein-Barr antibodies for fifteen to twenty years before the disease appeared.

Researchers aren’t sure why the virus is associated with multiple sclerosis, but they suspect it raises the risk for numerous autoimmune disorders.

So maybe it’s an understatement to call Epstein-Barr a wolf in sheep’s clothing. It sounds more like a pack of wolves managed to squeeze into this outfit.