Plenty of people have caught or know someone who’s had infectious mononucleosis, a.k.a. mono, in the past. A study out this week finds this notoriously miserable infection might cause even more serious trouble down the road.
Researchers at the Mayo Clinic and others examined the long-term health of people diagnosed with mono tied to the Epstein-Barr virus (EBV). People with a history of mono were three times more likely to later develop multiple sclerosis than those without, they found. The findings seem to provide an important clue as to why only a small percentage of people infected with EBV ever develop this debilitating condition.
“Our results add to the growing body of evidence linking EBV-positive IM infection to MS risk,” the researchers wrote in their paper, published Wednesday in the journal Neurology Open Access.
Common but rarely dangerous
Scientists have amassed considerable evidence in recent years that EBV, a type of herpesvirus, is the major leading cause of MS. But there remain many questions about the relationship between the two.
Just about everyone in the world contracts EBV at some point, after which the virus remains latent in the body. Yet only some people will become sick from the initial infection; even fewer develop MS (around 1%).
Mono is perhaps the most well-known manifestation of acute EBV-related illness, affecting a quarter of people who catch the virus in their teen or young adult years (that said, other infections can cause mono, too). It usually appears about a month after exposure to EBV, causing symptoms like a measles-like rash along with bouts of extreme fatigue, sore throat, and headaches. Most people will recover from mono within a few weeks, but it can take up to six months for some unlucky few.
Several studies have suggested that people who catch EBV-related mono are then more likely to develop MS. According to the authors, however, this research has largely looked at self-reported or indirectly ascertained cases of mono, limiting its reliability.
For the new study, the researchers analyzed the medical records of 4,721 people with mono linked to a confirmed positive test of EBV. They compared these people to a larger group of people (14,163) without mono who were matched in age and other characteristics.
The groups were followed for a median length of six to eight years. And though diagnosed MS cases were rare for both groups, people with mono had a clearly higher risk, the researchers found. Even after adjusting for other possibly relevant factors, such as a history of smoking or depression, people with past mono were over threefold more likely to come down with MS.
The need for prevention
Though the findings appear to confirm the role of mono in pushing people toward MS, it’s important to note that even most people with mono will never develop the condition. There is still more work needed to untangle the likely complex triggers behind MS.
For the study authors, however, the takeaway is clear: we urgently need vaccines that can effectively prevent EBV infection, or at least the sort of infection that might one day lead to MS.
“Together with previous studies, our findings highlight the importance of continued efforts to develop preventive strategies against EBV-positive IM,” they wrote.
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