Clinical Study Links Infectious Mononucleosis to Threefold Increase in Multiple Sclerosis Risk Over Two Decades

A new study finds that mononucleosis caused by the Epstein-Barr virus is associated with a 3x higher risk of MS, highlighting the need for viral prevention.

By: AXL Media

Published: Apr 2, 2026, 4:24 AM EDT

Source: Information for this report was sourced from American Academy of Neurology.

The Biological Link Between Common Viruses and Chronic Disease

A comprehensive longitudinal study has further clarified the relationship between common viral infections and the long-term risk of developing multiple sclerosis. The research, which utilized over twenty years of healthcare records, suggests that the Epstein-Barr virus (EBV) serves as a significant precursor to neurological complications when it manifests as infectious mononucleosis. While EBV is a pervasive herpes virus that often remains asymptomatic in the general population, its progression into a symptomatic illness during adolescence or adulthood appears to correlate with a heightened vulnerability in the central nervous system. This discovery emphasizes the potential for viral prevention strategies to act as a primary defense against the onset of chronic autoimmune disorders.

Analyzing Two Decades of Patient Health Records

The investigation, led by Dr. Jennifer L. St. Sauver at the Mayo Clinic, involved a meticulous comparison of more than 4,700 individuals who tested positive for mononucleosis against a control group of 14,163 people. By matching participants based on age and sex, researchers were able to isolate the impact of the viral infection over a multi-year follow-up period. The data showed that while the overall incidence of multiple sclerosis remains relatively low, the frequency of cases was markedly higher in the cohort that had previously battled mono. This large-scale data set provides a robust statistical foundation for understanding how early-life infections can ripple through a patient's health profile years later.

Statistical Disparity in Neurological Outcomes

The raw data from the study illustrates a clear divide in health outcomes between the two groups, with 0.17% of those who had mono developing multiple sclerosis compared to only 0.07% in the control group. When calculated through person-years—a metric that accounts for both the number of participants and the duration of their observation—the difference became even more pronounced. The mono-positive group saw 2.25 cases per 10,000 person-years, whereas the group without a history of the virus saw only 0.77 cases. These figures represent a significant statistical shift that persists even after researchers account for external variables.