Mono Infection Linked to Increased Risk of Multiple Sclerosis

A study published on April 1, 2026, in Neurology Open Access, an official journal of the American Academy of Neurology, has found that infectious mononucleosis, commonly known as mono, is associated with a significantly increased risk of developing multiple sclerosis (MS) later in life.

Researchers analyzing more than two decades of health records determined that individuals who contracted the Epstein-Barr virus (EBV) during their teenage years or adulthood—resulting in a clinical case of mono—were three times more likely to develop MS compared to those who did not experience the disease.

Study Statistics and Risk Factors

The research identified a 300% increase in MS risk for individuals with a history of mono. These findings remained consistent after researchers adjusted for race, smoking and underlying health conditions, including depression and diabetes.

According to the study data, 0.17% of the mono group developed MS, which represents 8 out of 4,721 individuals. This equates to 2.25 cases per 10,000 person-years.

In contrast, the control group saw a development rate of 0.07%, with 10 out of 14,163 individuals developing the condition. This represents 0.77 cases per 10,000 person-years.

The Role of the Epstein-Barr Virus

The Epstein-Barr virus is a common herpes virus that typically causes no symptoms in the majority of people. However, the timing of the infection appears to be a critical factor in the risk of developing MS.

While EBV infection is nearly universal, it often manifests as infectious mononucleosis only when contracted during the teenage years or adulthood. The study suggests that this specific manifestation of the virus is the event that escalates the risk of MS.

Researchers emphasized that the study shows an association between mono and MS, but it does not prove that mono caused by the Epstein-Barr virus directly causes the disease.

Public Health Implications

Although MS is relatively rare, it often develops when individuals are in their prime years of raising families and working, leading to high treatment costs and risks of significant disability.

These results highlight the need for further research into ways to prevent infection with the Epstein-Barr virus. Preventing these infections could reduce the overall burden of MS.

Jennifer L. St. Sauver, PhD, Mayo Clinic

The findings underscore the potential impact of preventative medicine. Because EBV is linked to the development of the disease, the creation of a vaccine could potentially reduce the global incidence of MS.

The study was supported by ModernaTX, Inc., a company currently developing vaccines aimed at EBV-associated conditions, including multiple sclerosis.