Yes, there is a link, according to a study published in Science in January 2022.
The cause of multiple sclerosis (MS) is unknown, but the Epstein-Barr virus, a herpes virus that can cause mononucleosis and is spread through bodily fluids like saliva, has long been thought to be a likely suspect. Establishing a causal relationship, however, has been difficult because Epstein-Barr infects about 95 percent of adults in the United States, while MS affects 0.2 percent of the population. In addition, MS symptoms don't usually appear until 10 years after an Epstein-Barr infection.
To find out if there is a link, researchers at the Harvard T.H. Chan School of Public Health analyzed data from more than 10 million military recruits over 20 years. Every two years, the scientists took blood samples to see whether the soldiers had been infected with the Epstein-Barr virus and to assess the relationship between that infection and MS onset during the period of active duty.
They discovered that the risk of MS increased 32-fold after infection with Epstein-Barr but was unchanged after infection with other viruses. Levels of a certain biomarker associated with nerve degeneration typical in MS increased only after an Epstein-Barr infection. These findings cannot be explained by any known risk factor for MS and suggest that the Epstein-Barr virus is the leading cause of MS, the researchers wrote.
The delay between infection with Epstein-Barr and the start of MS may be partially due to MS symptoms being undetected during the earliest stages; it also may be partially due to the relationship between the Epstein-Barr virus and the immune system, which is repeatedly stimulated whenever the virus reactivates.
The mechanism by which Epstein-Barr is linked to MS is unknown, but there are at least two theories. One is that the virus, which causes a lifelong infection in memory B cells, reactivates in the brain, triggering an immune and inflammatory response and damaging the surrounding tissue. The other is that the similarity between Epstein-Barr proteins and the host's proteins causes the immune system to attack healthy tissue.
An Epstein-Barr infection, which is nearly impossible to prevent without an effective vaccine, is confirmed through a blood test that detects antibodies. Nearly all adults in the United States have antibodies that reflect a current or past infection. At the moment, there is no cure, but targeting the virus with specific antiviral drugs or creating a vaccine for it could ultimately prevent or cure MS, according to the researchers.
Dr. Ascherio is professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health and professorof medicine at Harvard Medical Schoolin Boston. He was the lead author of the study on Epstein-Barr and multiple sclerosis published in Science.
