Only one of the MS patients had no evidence of the Epstein-Barr virus prior to diagnosis. And 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, considering that about 90% of adults have antibodies showing they’ve had Epstein-Barr — while nearly 1 million people in the U.S. are living with MS, according to the National Multiple Sclerosis Society.
The virus appears to be “the initial trigger,” Drs. William H. Robinson and Lawrence Steinman of Stanford University wrote in an editorial accompanying Thursday’s study. But they cautioned, “additional fuses must be ignited,” such as genes that may make people more vulnerable.
Epstein-Barr is best known for causing “mono,” or infectious mononucleosis, in teens and young adults but often occurs with no symptoms. 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.
