Childhood infectious mononucleosis a risk factor for subsequent MS diagnosis

Reuters Health - 29/10/2021 - Infectious mononucleosis (IM), an acute manifestation of the Epstein-Barr virus, is associated with an increased risk of developing multiple sclerosis (MS) if the infection occurs in childhood or adolescence, according to recent study findings.

"We believe that these more severe infections during childhood make it more likely that the virus causes sufficiently serious inflammation in the brain, triggering the immune system to attack myelin which is an insulating material around nerves that is required for them to function," Dr. Scott Montgomery of Orebro University in Sweden told Reuters Health by email.

Of almost 2.5 million people in the Swedish Total Population Register who were born in Sweden between 1958 and 1994, Dr. Montgomery and his colleagues found 5,867 (0.24%) who were diagnosed with MS at age 20 years or older over a median 15 years of follow-up. The median age at diagnosis was 31.5 years, the team reports in JAMA Network Open.

Adjusting for shared familial factors, IM during childhood was associated with a 2.87 times higher risk of MS (95% confidence interval, 1.44 to 5.74), while the risk was 3.19 times higher among those with IM during adolescence (95% CI, 2.29 to 4.46).

The risk of developing MS was also elevated for people who had IM in young adulthood, but this association was no longer significant after controlling for shared familial factors (HR, 1.51; 95% CI, 0.82 to 2.76).

Dr. Montgomery noted that the risk for later MS diagnosis was highest among children who had IM between the ages of 11 and 15 years, a time period in which puberty typically occurs.

"After age 15 years, the risk diminished with increasing age at IM until it was almost eliminated for IM by age 25 years," he said. "The immune system and central nervous system (CNS) must be particularly susceptible to exposures that cause inflammation in the CNS around puberty, with an increased risk of triggering the autoimmunity that can lead to MS."

Dr. Bruce Bebo, the executive vice president of research programs at the National MS Society in Houston, Texas, told Reuters Health in an email, "Adolescence appears to be a critical time for exposure to risk factors for MS, this may indicate a critical time of immune system maturation/education that alters risk for MS and perhaps other autoimmune diseases."

Perhaps one day "IM could be a component of" an "MS-risk calculator," suggested Dr. Bebo, who was not involved in the new research.

SOURCE: https://bit.ly/3plj1R1 JAMA Network Open, online October 1, 2021.

By Brandon May



Posted on 29 October 20219 November 2021