There’s strong, new evidence that one of the world’s most common viruses might set some people on the path to developing multiple sclerosis.
MS is a potentially disabling disease in which the body’s immune system mistakenly attacks the protective coating on nerve fibers, gradually eroding them and interfering with communication between the brain and the rest of the body
The Epstein-Barr virus has long been suspected of playing a role in development of MS. But it’s a connection that’s hard to prove because just about everybody gets infected at some point with Epstein-Barr, usually as kids or young adults — but only a tiny fraction develop MS.
Now, Harvard researchers are reporting the results of one of the largest studies to back the Epstein-Barr theory.
They tracked blood samples stored from more than 10 million people in the U.S. military and found the risk of MS increased 32-fold following Epstein-Barr infection.
The military regularly administers blood tests to its members. The researchers checked samples stored from 1993 to 2013, hunting for antibodies signaling viral infection.
Just 5.3% of recruits showed no sign of Epstein-Barr when they joined the military. The researchers compared 801 MS cases subsequently diagnosed over the 20-year period with 1,566 service members who never got the disease.
Only one of the MS patients had no evidence of the Epstein-Barr virus prior to diagnosis. Despite intensive searching, the researchers found no evidence that other viral infections played a role.
The findings “strongly suggest” that Epstein-Barr infection is “a cause and not a consequence of MS,” study author Dr. Alberto Ascherio of the Harvard T.H. Chan School of Public Health and colleagues reported in the journal Science.
It’s clearly not the only factor, given that about 90% of adults have antibodies showing they’ve had Epstein-Barr — and nearly one million people in the United States are living with MS, according to the National Multiple Sclerosis Society.
The virus appears to be “the initial trigger,” Dr. William H. Robinson and Dr. Lawrence Steinman of Stanford University wrote in an editorial accompanying the study.
But they wrote, “Additional fuses must be ignited,” such as genes that might make people more vulnerable.
Epstein-Barr is best known for causing “mono,” or infectious mononucleosis, in teenagers and young adults, but it also often occurs with no symptoms at all. A virus that remains inactive in the body after initial infection, it also has been linked to later development of some autoimmune diseases and rare cancers, though it’s not clear why.
Among the possibilities: “molecular mimicry,” meaning viral proteins might look so similar to some nervous system proteins that it induces the mistaken immune attack that occurs with MS.
