SCIENTISTS have found the strongest evidence to date that an infection from the Epstein-Barr virus (EBV) could significantly increase the risk of developing multiple sclerosis (MS), a degenerative disease.

“Our data strongly suggest EBV is the leading cause of MS,” said Kjetil Bjornevik, a research scientist at Harvard T.H. Chan School of Public Health and lead author of the study, which was published in the journal Science. The finding offers hope that a vaccine or early treatment of the virus could one day help prevent multiple sclerosis, according to Alberto Ascherio, an author of the study and epidemiology professor at the school.

But experts unaffiliated with the study say there’s still uncertainty about whether the virus causes MS. Multiple sclerosis, a progressive disease that affects the brain and spinal cord, is caused by inflammation that attacks myelin, the fatty tissue surrounding the nerves, according to the U.S. National Institutes of Health.

When myelin degrades, it’s more difficult for the nerves to send messages to the brain, causing blurred vision, weak limbs, tingling sensations, unsteadiness, and fatigue, according to the Multiple Sclerosis International Federation. In advanced cases, patients can have muscle weakness in their arms and legs, making it difficult to walk or stand.

To determine the link between an EBV infection and MS, scientists analyzed samples from the U.S. Department of Defense Serum Repository, a collection of more than 60 million blood samples taken from more than 10 million active and reserve duty members every few years.

The scientists compared blood samples of 1,566 service members who didn’t develop MS to samples from 801 service members who received an MS diagnosis during the course of the study. Of those individuals, 107 members of the control group and 35 members of the group that subsequently developed MS started off without an EBV infection.

By the end of the study, 34 of the 35 people who developed MS had been infected with EBV at some point during the study. In these cases, the infection always preceded the diagnosis. In other words, all but one person in the study who developed MS had a previous EBV infection, and having that infection increased the likelihood of getting MS later in life by 32-fold in the study, the scientists found.

It’s difficult to definitively prove that EBV, which is also the virus behind mononucleosis, causes MS.

Although it’s the most authoritative study to date, the way the study is designed means scientists can’t know with absolute certainty that the virus causes the disease, said Alan Thompson, dean of the Faculty of Brain Sciences from University College London and a peer reviewer on the new paper.

(SD-Agencies)