Common Virus Linked To Multiple Sclerosis Development, Study Finds

The common Epstein-Barr virus (EBV) may just be the "leading cause" of multiple sclerosis (MS), a team of researchers has found. This is said to be a "big step" for possibly preventing the disease.

MS is a "potentially disabling" disease of the central nervous system wherein the immune system attacks the protective sheath covering the nerve fibers, Mayo Clinic explained. This leads to issues in communication between the brain and the rest of the body.

Though about 2.8 million people are affected by MS worldwide, there is still no "definitive" cure for the disease and its cause has remained unclear, Harvard T.H. Chan School of Public Health [Harvard Chan School] noted in a news release.

One of the hypothesized causes of MS is EBV. This is a known human herpes virus that causes illnesses such as infectious mononucleosis, commonly known as mono. According to the Centers for Disease Control and Prevention (CDC), it is among the most common human viruses, with most people likely to get infected with it "at some point in their lives."

However, establishing a cause-and-effect relationship between EBV and MS hasn't been easy since EBV is so common and MS is so rare. Furthermore, the onset of MS symptoms takes about 10 years to begin after getting infected with EBV, Harvard Chan School said.

For their study, published Thursday in Science, a team of researchers tested the hypothesis by looking at more than 10 million young adults who were on active duty in the U.S. military. These members had their blood screened at the beginning of their service and every two years thereafter. This meant the researchers were able to test their EBV status from the first sample then monitor the relationship between EBV and MS throughout their time of being on active duty.

Among the participants, 955 were eventually diagnosed with MS during their service, with MS risk increasing by 32-fold after EBV infection but not with other viruses. The difference was "so high" that it was unlikely to be a coincidence and "provides compelling evidence of causality," Marianna Cortese of Harvard Chan School, one of the study authors, told Gizmodo.

"Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion," the researchers wrote. "These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS."

Alberto Ascherio of Harvard Chan School, senior author of the study, called the discovery a "big step" as it shows a potential pathway to possibly avoiding MS by preventing EBV first.

"Currently there is no way to effectively prevent or treat EBV infection, but an EBV vaccine or targeting the virus with EBV-specific antiviral drugs could ultimately prevent or cure MS," Ascherio said, as per Harvard Chan School.