There is more evidence that one of the world’s most common viruses may put some people on the path to developing multiple sclerosis.

Multiple sclerosis is a potentially disabling disease that occurs when immune system cells mistakenly attack the protective coating on nerve fibers, gradually eroding them.

Epstein-Barr virus has long been suspected of playing a role in the development of MS. That’s a difficult link to prove, because nearly everyone gets Epstein-Barr, usually a child or young adult — but only a small percentage gets MS.

On Thursday, researchers at Harvard University reported one of the largest studies to support the Epstein-Barr theory.

They tracked blood samples stored by more than 10 million people in the U.S. military and found a 32-fold increased risk of MS after Epstein-Barr infection.

The military regularly conducts blood tests of its members, and researchers examined samples stored between 1993 and 2013, looking for antibodies that indicate viral infection.

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Only 5.3 percent of recruits showed no signs of Epstein-Barr when they joined the military. The researchers compared 801 cases of MS diagnosed over a 20-year period with 1,566 service members who never had MS.

Only one MS patient had no evidence of Epstein-Barr virus before diagnosis. Despite an intensive search, the researchers found no evidence that other viral infections played a role.

The findings “strongly suggest” that Epstein-Barr infection is “a cause rather than a result of MS,” study author Dr. Alberto Ascherio of the Harvard TH Chan School of Public Health and colleagues report in the journal Science.

Considering that about 90 percent of adults have antibodies that indicate they have Epstein-Barr, that’s clearly not the only factor, according to the National Multiple Sclerosis Society — and nearly 1 million people in the U.S. have MS.

The virus appears to be the “initial trigger”, Drs. Stanford University’s William H. Robinson and Lawrence Steinman wrote in an editorial on Thursday’s study. But they warn that “additional fuses must be lit,” such as genes that could make people more vulnerable.

Epstein-Barr is known for causing “mononucleosis,” or infectious mononucleosis, in teens and young adults, but usually has no symptoms. The virus remains inactive in the body after initial infection, and it has also been linked to the later development of some autoimmune diseases and rare cancers.

It’s unclear why. One possibility is so-called “molecular mimicry,” meaning that a viral protein might look so similar to certain nervous system proteins that it induces the wrong immune attack.

Regardless, the new study is “the strongest evidence to date that Epstein-Barr contributes to MS,” said Mark Allegretta, vice president of research at the National Multiple Sclerosis Society.

This, he added, “opens the door to potential MS prevention by preventing Epstein-Barr infection.”

Attempts to develop an Epstein-Barr vaccine are underway, including a small study just started by Moderna Inc., best known for its COVID-19 vaccine.