Is previous infection by EpsteinBarr Virus (EBV) or Cytomegalovirus (CMV) a considerable risk factor for the development of Multiple Sclerosis (MS) in adults?

Background and objective: Multiple Sclerosis (MS) is a neurodegenerative, inflammatory and demyelinating disease of the central nervous system. The mechanisms that cause MS are still unknown. However, many variables appear as possible risk factors for the development of this disease. Therefore, this review aims to analyze the prevalence of MS cases in adult patients with a history of previous Epstein-Barr (EBV) or Cytomegalovirus (CMV) infection. Design and settings: This study is a literature review, produced in Bahiana School of Medicine and Public Health, Salvador, Bahia, Brazil. Methods: The studies evaluated were observational studies, published from 2016 to 2021, obtained in PubMed, with MeSH terms, published. The studies that did not correspond with the purpose of this review were excluded. Results: The search resulted in 254 articles, of which 60 were selected. In cohort studies, EBV was indicated as a relevant risk factor and CMV was identified as a protective factor. Besides, cross-sectional studies differ in relation to CMV being considered a risk or protection factor, while EBV was pointed out as a risk factor again. However, case-control studies show that there is no association between Epstein-Barr or Cytomegalovirus with the risk of developing Multiple Sclerosis. Conclusion: The evidence is still very uncertain, mainly due to the quality of the studies produced so far. Further studies of better methodological quality are needed to prove whether there is a causal association between these factors.