Past infection with the Epstein-Barr virus (EBV) and a history of glandular fever (infectious mononucleosis) are associated with an increased risk of multiple sclerosis (MS) across multiple ethnic groups, research has found.
The authors of the study, who used data on black, white and hispanic Americans, said the consistency of the findings across ethnic groups supported a true biological link between EBV infection and MS
“Studies like ours that include participants from multiple racial groups can be a strong tool to test for biological risk factors, especially when the frequency of exposures to biological factors like Epstein-Barr virus and mononucleosis differ between groups,” said lead author, Annette Langer-Gould, from the department of research and evaluation at Kaiser Permanente, Southern California. “If the findings were not the same across all groups, it would be less likely that a link would be biological.”
The case-control study, which was published in Neurology, involved a total of 239 black participants, 360 hispanic and 491 white who were enrolled over a three-year period.
The researchers found that EBV seropositivity was independently associated with the odds of incident MS or clinically isolated syndrome in each of the three ethnic groups, after adjustment for confounders. The same was also true of self-reported history of glandular fever.
By contrast, exposure to another early-life infectious agent, cytomegalovirus, was inconsistently associated with MS risk across the ethnic groups, which the team indicates a non-causal link.
EBV has previously been linked to MS but the overwhelming majority of research has only included white participants.
The researchers said their findings supported the ‘hygiene hypothesis’ — that a lack of exposure to infection early in life disposes individuals in developed countries to the development of allergic and autoimmune disease. EBV is usually not serious if contracted early in life but symptoms of glandular fever can be severe in adolescence and adulthood.
 Langer-Gould A, Wu J, Lucas R et al. Epstein-Barr virus, cytomegalovirus, and multiple sclerosis susceptibility. Neurology 2017; 89:1–8. doi: 10.1212/WNL.0000000000004412