Some patients show clinical evidence of multiple sclerosis (MS) prior to documented Epstein-Barr virus (EBV) infection, according to study results presented at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) 2026, held from February 5 to 7, in San Diego, CA.
Researchers conducted a population-based assessment to assess whether clinical indicators of MS could precede laboratory evidence of primary EBV infection. The researchers used linked laboratory and health administrative data from Ontario, Canada, encompassing approximately 16 million residents between January 2007 and December 2022. Laboratory data captured more than 80% of EBV testing performed across hospital, community, and public health settings.
Individuals with serologic evidence of primary EBV infection were identified using positive heterophile antibody or viral capsid antigen immunoglobulin M results, and MS cases were determined using a validated claims-based algorithm requiring multiple MS diagnostic codes and at least 1 demyelinating disease–related diagnosis before the EBV index date.
Further research is required to evaluate possible explanations for EBV infection, or the possibility that some cases of MS may be due to other infections or environmental exposures.
Among 95,980 individuals with laboratory evidence of primary EBV infection, 0.31% (n=300) met criteria for MS. Of these, 24.7% of individuals (n=74) had documentation of at least 1 demyelinating disease-related code before the EBV index date. In this subgroup, the mean (SD) age at MS onset was 33.3 (14.3) years, and 75.7% (n=56) of patients were women.
The mean (SD) age at first positive EBV test among these patients was 42.5 (16.1) years, compared with 21.5 (10.6) years among all individuals with positive EBV testing. Overall, 78.4% (n=58) of the patients with documentation of at least 1 demyelinating disease-related code before the EBV index date met MS criteria prior to their first documented EBV test. Additionally, 93.2% (n=69) of these patients had a demyelinating disease–related claim at least 90 days before EBV detection.
In her presentation at ACTRIMS, Dalia Rotstein, MD, MPH, said, “It is premature to use EBV serostatus to rule out an MS diagnosis.”
“Further research is required to evaluate possible explanations for EBV infection following MS onset, including misdiagnosis of MS, misclassification of EBV infection, reactivation of EBV infection, or the possibility that some cases of MS may be due to other infectious or environmental exposures,” the study authors conclude.
date: 2026-02-09 15:01:00