A Viral Suspect in Multiple Sclerosis

Study fingers Epstein-Barr virus

WEDNESDAY, Dec. 26, 2001 (HealthDayNews) -- Researchers say they have turned up a possible link between multiple sclerosis (MS) and the Epstein-Barr virus, which is best known as the cause of infectious mononucleosis.

Going through the records of two large studies in which thousands of women gave blood samples, a team led by Dr. Alberto Ascherio of the Harvard School of Public Health found that unusually high levels of antibodies triggered by the virus are associated with the onset of MS.

Epstein-Barr is one of the most common viruses, infecting as many as 95 percent of American adults. The immune system normally produces antibodies against the virus, but the levels of those antibodies generally decline after a few months. In this study, elevated levels of antibodies were associated with a four-fold increased risk of MS, a chronic degenerative disease in which repeated episodes of inflammation destroy the covering of nerve cells, causing weakness, movement problems, pain and paralysis. MS affects about 350,000 Americans.

"For decades it has been suspected that MS is caused by some form of infection in genetically susceptible individuals, but the organisms that are responsible for it have remained elusive," says a statement by Ascherio, an associate professor of epidemiology and nutrition at Harvard. "Our results suggest that Epstein-Barr virus may be the culprit, or at least one of the culprits."

But the cause-and-effect relationship is far from clear, says a report in today's Journal of the American Medical Association. The findings "offer evidence that Epstein-Barr virus infection may increase the risk of MS," the researchers write, but they add that "because few individuals infected with Epstein-Barr virus develop MS, other co-factors are required. These may include genetic predisposition and, perhaps, age at primary infection or infection with other microbes."

The finding is one piece in a complex puzzle, says Nicholas G. LaRocca, director of health-care delivery and policy research at the National Multiple Sclerosis Society. "We think of MS as a puzzle with many pieces, immunological, genetic and possibly environmental," he says. "Studies looking at infectious agents are trying to find what some possible environmental factors may be."

Many researchers have looked for a link between Epstein-Barr, other viruses and MS, LaRocca says. "It was an active line of research for many years, but the results were disappointing. It has come back somewhat in the last few years."

New techniques have revived the search, says an accompanying editorial by Dr. Donald H. Gilden of the University of Colorado Health Sciences Center. "The potential to identify rare or low-level pathogens has improved, and the molecular virologic strategies and techniques available today allow studies of virus detection not possible 20 years ago," he writes.

Noting that other viruses also have been named as possible culprits, Gilden says, "Although the cause of MS is not likely to be found under the Epstein-Barr virus lamppost, the search for a viral cause of MS must continue."

What To Do

"A better understanding of the mechanisms that relate Epstein-Barr virus to MS may also lead to novel therapeutic approaches," the researchers say.

For basic information about MS and help for patients, consult the National Multiple Sclerosis Society. Extensive information about MS and other neurological diseases is offered by New York Online Access to Health.

SOURCES: Interview with Nicholas G. LaRocca, director of health-care delivery and policy research, National Multiple Research Society, New York City; Dec. 26, 2001, Journal of the American Medical Association
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