A common virus that causes mononucleosis – the ‘kissing disease’ – could more than triple the risk of developing multiple sclerosis, a devastating autoimmune disease that ravages the central nervous system.
Infectious mononucleosis is the symptomatic form of Epstein-Barr virus (EBV), one of the most common human viruses, infecting approximately 95 percent of the US population. Now, a major new study quantifies just how dangerous being infected with both viruses can be.
Researchers tracked nearly 19,000 people and found that children and young adults who had lab-confirmed EBV followed by symptomatic mono were significantly more likely to develop multiple sclerosis (MS) later in life compared to those who never had EBV-positive mono.
Of the more than 4,700 people with EBV-positive mono, eight went on to develop MS — a rate more than double that of the uninfected group.
Multiple sclerosis affects about one million Americans. The disease occurs when the immune system mistakenly attacks the protective covering of nerves in the brain and spinal cord, scrambling signals between the brain and the body.
Symptoms include muscle weakness, vision loss, numbness, severe fatigue, and trouble with balance. Over time, the damage can become permanent and disabling.
The exact cause of MS remains unknown, but scientists believe a combination of genetics, environmental triggers, and viral infections — especially EBV — plays a key role.
Experts say the findings, published from a population-based study using medical records from the Mayo Clinic-led Rochester Epidemiology Project, underscore the urgent need for preventive strategies, including a potential EBV vaccine, to reduce the long-term toll of the devastating neurological disease.
Saliva is the main route for EBV transmission. When teens catch the virus for the first time and develop mono, kissing is usually how it spreads, which is why the illness is often called ‘the kissing disease’ (stock)
Infectious mononucleosis, commonly known as mono, is extremely widespread, especially in teens and young adults, with about 500 out of every 100,000 people in the US getting it each year.
Although roughly 90 to 95 percent of people carry the Epstein-Barr virus, only about one in four who are exposed actually develop symptoms of mono.
EBV is primarily spread through saliva. In teens who are first exposed and develop mono, transmission typically occurs via kissing, earning the infection the nickname ‘the kissing disease.’
Mono typically causes extreme fatigue, a severe sore throat, fever and swollen lymph nodes in the neck and armpits.
Many people also develop swollen tonsils with white patches, headaches, body aches and an enlarged spleen, which can rupture if the person engages in contact sports or heavy lifting too soon.
While symptoms usually peak within two to four weeks, the fatigue can linger for months, especially in teenagers and young adults, who tend to experience more severe symptoms than younger children.
For the recent study, researchers conducted a population-based study using medical records from the Rochester Epidemiology Project, which covers southeastern Minnesota and western Wisconsin.
They identified 4,721 individuals who had both laboratory-confirmed EBV infection, verified through monospot tests or antibody testing showing recent infection, and a corresponding diagnosis code for infectious mononucleosis.
Selma Blair was diagnosed with relapsing-remitting multiple sclerosis in 2018 after decades of unexplained symptoms, and she later underwent aggressive stem cell transplantation that put her MS into remission
Christina Applegate revealed her multiple sclerosis diagnosis in August 2021, sharing that she had been living with symptoms like numbness and tingling for years before finally getting answers
This group, which was 55 percent female and 70 percent under age 20, formed the cohort exposed to both EBV and mono.
Each of these individuals was matched by age and sex to three people without that exposure to make 14,163 people total who had no evidence of EBV-positive mono during the study period.
The researchers then followed both groups from the day their positive test came back through September 2023, tracking the development of MS.
Over roughly six to eight years of monitoring, eight people who had mono caused by EBV went on to develop multiple sclerosis, or 0.17 percent of that group.
Among those who never had EBV-positive mono, ten people developed MS — just 0.07 percent of that group.
After accounting for factors such as race, smoking, and overall health, researchers found that people who had lab-confirmed EBV followed by mono were 3.14 times as likely to develop MS as those who did not.
The study, published in Neurology Open Access, also found that MS appeared sooner in the mono group — a median of 9.7 years after infection versus 14.2 years in the non-mono group.
That suggests symptomatic EBV infection may not only increase the risk of MS but also speed up its arrival.
The risk of death was the same in both groups. Other rare brain and spinal cord disorders were not included in the final analysis because too few people developed them.
The vast majority of MS sufferers are white women in northern Europe, Canada and the northern half of the US. The autoimmune disorder affects roughly one million Americans
Just because people with EBV-positive mono are three times more likely to develop MS does not mean mono causes MS.
The study found an association — a strong statistical link — but not proof of cause and effect.
Almost everyone with MS may have had EBV at some point. In fact, over 99 percent of people with MS show evidence of past EBV infection, compared to about 90 to 95 percent of the general population.
But the vast majority of people who catch EBV, even those who get sick with mono, will never develop MS.
