The Epstein-Barr virus (EBV) may be the leading cause or trigger of multiple sclerosis (MS), a study led by Harvard researchers suggests.
MS is a progressive, neurodegenerative disease of the brain and spinal cord that affects 2.8 million people worldwide, nearly 1 million of whom are in the United States. The cause of MS has not been established although many have suspected EBV, a member of the herpesvirus family that can cause infectious mononucleosis, also called “kissing disease.” EBV can also establish a lifelong latent infection in the individual.
“The hypothesis that EBV causes MS has been investigated by our group and others for several years, but this is the first study providing compelling evidence of causality,” said Alberto Ascherio, professor of epidemiology and nutrition at Harvard Chan School and the senior author of the study, in a statement.
“This is a big step because it suggests that most MS cases could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for MS.”
Authors say establishing a causal relationship between EBV and MS has been hard because EBV infects about 95 percent of adults while MS is relatively rare, and the onset of MS symptoms takes place about 10 years after initial EBV infection.
In the study, published online in the journal Science on Jan. 13, researchers observed more than 10 million young adults on active duty in the U.S. military, of whom 955 were diagnosed with the condition during their service.
Researchers analyzed blood samples taken every two years (during routine HIV testing) by the military, and analyzed up to three blood samples for each soldier with MS.
The researchers assessed the soldiers’ EBV status at the time of the first sample (taken when most in the military were under 20 years old), and the relationship between EBV infection and MS onset throughout their period of active duty.
“Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus,” authors wrote.
Authors also found that serum levels of neurofilament light chain (NfL)—a biomarker of nerve degeneration that’s typical in MS—increased only after EBV infection.
Past studies suggest that NfL levels rise a few years before MS onset.
“These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS,” authors said in their report, titled “Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis.”
Immunologists William H. Robinson and Lawrence Steinman from Stanford University said in an accompanying commentary, “These findings provide compelling data that implicate EBV as the trigger for the development of MS.”
Virologist Jeffrey I. Cohen, who heads the Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases (NIAID), who was not involved in the research, told The Scientific American that he is cautious about claiming causation, and it still must be shown that preventing EBV prevents MS, but acknowledges the results are significant.
“When the original studies were done with cigarette smoking and lung cancer, they found a 25-fold risk factor for people who smoked more than 25 cigarettes a day,” Cohen told the magazine. “This is even higher.”
Ascherio said that a possible reason why the onset of MS is much delayed from the initial EBV infection could be because symptoms are not notable or are undetected in the early stages of MS, and could also be due to how EBV interacts with the infected person’s immune system, which is stimulated whenever the latent EBV virus reactivates.
“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 suggested.
Anthony William, the No. 1 New York Times best-selling author of the Medical Medium book series, asserts in his book “Medical Medium Thyroid Healing” that the Epstein-Barr virus “is the hidden cause of MS.”
An article on his website details the proposed steps to take, as well as foods to eat and foods to avoid, for a person who wants to drastically reduce symptoms of MS. William notes that his content is “for informational purposes only and are not a substitute for medical advice, diagnosis, treatment, or prescribing.”
MS involves the immune system attacking the protective sheath, or myelin, that covers nerve fibers, disrupting communications between the brain and the rest of the body. Symptoms range from mild to severe, and include numbness or weakness in the limbs affected, slurred speech, fatigue, vision issues, and problems with bowel and bladder function.
According to the Mayo Clinic, most MS sufferers experience a relapsing-remitting disease course—periods of new symptoms or relapses over days or weeks that usually improve partially or completely, followed by periods of remission that can last months or years.