Infection with Epstein-Barr virus (EBV), resulting in infectious mononucleosis, which primarily effects adolescents and young adults, more than doubles the risk of developing multiple sclerosis (MS) later in life, results of a large review of studies suggest.

“Multiple sclerosis is a complicated disease, probably caused by a combination of factors,” lead author Evan L. Thacker from the Harvard School of Public Health, Boston, told Reuters Health. “It is likely that some viral infections, such as infectious mono, play a role in determining whether multiple sclerosis will occur.”

Similarities in the patterns of infectious mononucleosis and MS led the researchers to consider EBV as a cause of MS, Mr. Thacker and two colleagues from Harvard point out in the Annals of Neurology.

Both conditions occur in young adults, both are more prevalent in certain geographic locations and both are rare in populations in which infections occur at an early age, suggesting that late infection with EBV, evidenced by occurrence of infectious mononucleosis, is an important causal factor in MS,” they explain.

However, studies that have evaluated the relationship between infectious mononucleosis and MS risk have produced inconsistent results.

Against this backdrop, the Harvard group systematically identified and statistically combined 14 relevant studies conducted in the US, Europe, and Australia to come up with an overall picture of the connection between infectious mono and MS.

“The most important observation in our study was that people who got infectious mono while growing up were about twice as likely to get multiple sclerosis later, compared to people who never got infectious mono,” Thacker told Reuters Health.

“The potential implication of our observation is that some cases of multiple sclerosis could probably be averted through the prevention of infectious mono,” he said. “One way to accomplish this might be to develop a safe and effective vaccine against Epstein-Barr virus.”

SOURCE: Annals of Neurology, March 2006.