The causes of multiple sclerosis (MS) are complex, but recent research has found that Epstein Barr virus, the same virus that causes mononucleosis, is an environmental trigger for MS.
Canada has one of the highest levels of multiple sclerosis (MS) in the world, with 250 per 100,000 people affected.
MS is an autoimmune disease in which the elements of the immune system that are designed to protect us – white blood cells and antibodies – begin to damage the brain and spinal cord. This causes acute attacks – also known as relapses – of neurological dysfunction, such as vision loss, difficulty walking or urinary and sexual dysfunction.
Activation of the environment
But what causes MS? The answer is complex. MS is caused by a combination of factors, including a genetic predisposition to the disease (birth with genes that cause MS), an abnormal immune system that attacks instead of defending, and an environmental trigger.
In a study published in the journal Science, researchers found that Epstein Barr virus (EBV) – the virus that causes mononucleosis – is also an environmental factor for MS. EBV is a common occurrence, with more than 95% of people infected in their lifetime.
In this study, researchers examined the blood of a large group of adults and continued to monitor their health for 20 years. The results show that 34 of the 35 people who developed MS who were initially negative for EBV tested positive for the virus before being diagnosed with MS. This contrasts with 57% of controls (those without MS) that tested positive for EBV.
This does not mean that if you have had Epstein-Barr virus, you will definitely develop MS. However, the study found that new EBV infection in adults increased the risk of developing MS by 32 times. No increase in the risk of MS has been observed for other viral infections.
Identification of the main risk factor
This document describes the biggest risk factor for MS discovered so far. Importantly, the study did not look at children or adolescents, so it is not known whether the presence of mononucleosis before the age of 18 would increase the risk of MS.
Evidence that EBV infection puts someone at high risk for MS is an important finding. This means that researchers can start designing preventative treatments for MS, such as vaccines and antivirals, such as those that protect against SARS-CoV2, the virus that causes COVID-19.
Other studies have shown that EBV infection in people who have already been diagnosed with MS can change their immune system from one that protects them from disease to one that attacks the brain and spinal cord. This is an immune response that is specific to EBV. This suggests that even in people with MS, focusing on treatments designed to prevent EBV from altering the immune system would be a new strategy to prevent progression.
Discovering the link between EBV and the risk of MS is a crucial part of the MS puzzle, opening up new potential treatments for people living with this condition.
Michael C. Levin does not work for, consult, hold, or receive funding from any company or organization that would benefit from this article, and has not disclosed any relevant links outside of their academic assignment.
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