It Enters the Body with a Kiss and Stays for a Lifetime!

A new study that involves millions of people in the United States has revealed striking findings regarding the link between the Epstein‑Barr virus (EBV), an infection popularly known as "the kissing disease", and multiple sclerosis (MS) attacks. Researchers determined that immune‑system activity associated with the virus can rise months before an attack in MS patients.

Three Months Before an MS Attack, It Sent a Signal

In a study published in Nature Medicine, blood samples from 114 MS patients and 21 healthy participants were examined. Scientists found that in the immune cells of MS patients, activity linked to EBV increased up to three months before some attacks.

MS attacks can manifest with muscle weakness, vision problems, numbness, and severe fatigue.

The study particularly identified pronounced changes in B cells, where EBV can hide in the body. These cells were seen to shift from a normal state to a more active immune condition, and that activity increased before an MS attack.

The Virus Can Remain in the Body for a Lifetime

Epstein-Barr virus, a member of the herpesvirus family, is highly prevalent. It is estimated that roughly 90 to 95 percent of people become infected with EBV at some point in their lives.

The virus is primarily transmitted through saliva. In adolescents and young adults, infection can sometimes lead to infectious mononucleosis, also known as the "kissing disease."

Once EBV enters the body, it does not disappear entirely. The typically dormant virus can reactivate under certain conditions.

The link to multiple sclerosis has been investigated for years.

Multiple sclerosis is a chronic neurological disease that arises when the immune system attacks the protective covering of nerves in the brain and spinal cord. In the United States, about one million people are estimated to live with MS.

The potential link between EBV and MS is one of the topics that the scientific community has been studying for a long time. Earlier studies had shown a strong association between EBV infection and the risk of developing MS.

The new study, however, presents new data indicating that the virus may be linked not only to the disease's progression but also to attacks in existing MS patients.

Notable Change in B Cells

Researchers used the 'single-cell RNA sequencing' method, which allows them to examine thousands of blood cells individually.

The results showed that the strongest changes appeared in B cells. It was noted that signals associated with EBV, along with the activity of certain genes linked to MS susceptibility, were observed before an MS attack.

The fact that the same pattern was not observed in periods when patients were attack-free or in healthy participants caught the researchers' attention.

Could Open the Door to New Treatments

The study's senior author, Dr. Tanuja Chitnis, said the findings could open a new research area for developing more targeted therapies.

Today, many MS treatments rely on broadly suppressing immune system activity. Researchers, however, believe that future approaches could target EBV directly or specific immune cells involved in the attack process.

However, the study does not prove that EBV activity directly causes an MS attack, nor does it propose a new method to prevent attacks based on current findings. What researchers have identified is the relationship between EBV‑related immune changes before an attack and MS activity.

Eyes in EBV Vaccine Studies

In another study published in April 2026, the health records of about 19,000 people were examined, and it was reported that children and young adults who had symptomatic mononucleosis confirmed by laboratory‑verified EBV infection had a higher likelihood of developing MS in subsequent years.

Scientists say that a more detailed understanding of the relationship between EBV and MS is important not only for new treatments but also for determining whether future EBV vaccines could play a role in preventing MS.