Multiple Sclerosis Society of Canada


New Study Shows that Epstein-Barr Virus is Associated with the Development of Multiple Sclerosis and Sparks Hope for the MS Community

  • National News Release

Study examined blood samples and clinical data from more than 10 million U.S. military personnel collected over 20 years; strongly suggests the virus is a trigger for MS

TORONTO, ON (Jan. 18, 2022) – A large longitudinal study from a Harvard University research team has shown striking new evidence that the Epstein-Barr virus (EBV) is a leading trigger of MS. The study showed risk of MS increased by 32-fold after infection with EBV but did not increase with other viruses.

The causes of MS are believed to be a combination of genetic and environmental factors. This study presents the most significant evidence to date that EBV is a leading cause or initial trigger for the development of MS, as an environmental risk factor.

Canada has one of the highest rates of MS in the world, with approximately 90,000 people living with the autoimmune disease. MS is caused when the immune system attacks the protective sheaths surrounding nerve fibres called myelin, resulting in inflammation and damaged myelin which can disrupt nerve signals between the brain and body. This disruption can affect vision, memory, balance, and mobility.

EBV is a common virus, with an estimated 90 per cent of all adults infected at some point over their lifetime. EBV is the primary cause of infectious mononucleosis, commonly referred to as the “kissing disease.” While the virus does not cause MS in everyone who gets it, it has long been suspected of being an environmental risk factor for MS.

The research team examined a cohort of 10 million U.S. military personnel over two decades. About five per cent of military personnel (several hundred thousand people) did not have EBV when they joined the military, and 955 individuals eventually developed MS. Additionally, only one participant with MS out of the 801 MS cases examined had no evidence of EBV infection.

The study results showed that individuals who were infected with EBV were 32 times more likely to develop MS. The researchers also found that serum levels of neurofilament light chain, a biomarker of MS neuropathology and neurodegeneration, was increased only after EBV infection, suggesting EBV infection preceded the development of MS.

The study’s main author, Dr. Alberto Ascherio, says the findings “strongly suggest” that the virus is a “cause and not a consequence of MS.” Many other researchers have also spoken with significant optimism for what this could mean for future research and interventions.

Globally, researchers are investigating EBV and its role in MS. The MS Society currently funds Dr. Marc Horwitz at the University of British Columbia on research into EBV to understand the influence of EBV on MS and the underlying mechanisms in the development and progression.

“This study enhances our understanding of EBV and the risk factors and triggers of MS,” says Pam Valentine, President and CEO, MS Society of Canada. “While we still need to understand the underlying biology or mechanisms of action of EBV and its role in the development of MS, or why not all individuals with EBV go on to develop MS, it does provide hope for new intervention strategies and approaches that target EBV.”

It is important to note that although EBV may act as a triggering event for MS, disease development could also be influenced by or further triggered by other risk factors for MS, such as vitamin D status and smoking.

To learn more and donate to MS research, visit


About multiple sclerosis and the MS Society of Canada

Canada has one of the highest rates of multiple sclerosis in the world. On average, 12 Canadians are diagnosed every day. MS is a chronic autoimmune disease of the central nervous system (brain, spinal cord). It is considered an episodic disability meaning that the severity and duration of illness and disability can vary and are often followed by periods of wellness. It can also be progressive. Most people are diagnosed with MS between the ages of 20 and 49 and the unpredictable effects of the disease will last for the rest of their lives. The MS Society provides information, support and advocacy to people affected by MS, and funds research to find the cause and cure for the disease, bringing us closer to a world free of MS. Please visit or call 1-800-268-7582 for more information, to get involved, or to support Canadians affected by MS by donating.

Join the conversation and connect with the MS community online. Find the MS Society on Twitter, Instagram or like our page on Facebook.


Ian Royer
Director, Public Relations & Strategic Communications

MS Society of Canada

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