Influence of CMV/EBV serostatus on respiratory infection incidence during 4 months of winter training in a student cohort of endurance athletes

Aim: The purpose of this study was to examine the influence of previous infection with cytomegalovirus (CMV) or Epstein Barr virus (EBV) on the incidence, severity and duration of upper respiratory tract infections (URTIs) in endurance athletes during a 4-month winter training period. Methods: Blood samples were obtained from 236 subjects (166 males and 70 females, aged 18-35 years) at the start of the study period. Plasma samples were analysed for CMV and EBV serostatus. Weekly training and daily illness logs were kept for the next 16 weeks. Results: With regard to CMV/EBV serostatus, the results indicated that athletes with previous CMV infection (n = 58, 25 % of cohort) had significantly fewer URTI symptom days (median 2 vs. 4 days, p = 0.033) during the study period than those with no previous infection (n = 178, 75 %), whereas positive EBV serostatus (n = 197, 84 %) had no influence on URTI episode incidence, severity or duration. Moreover, we found that athletes with prior infection of both CMV and EBV (n = 50, 21 %) had 50 % fewer URTI episodes (p = 0.04) and symptom days (median 2 vs 8 days, p = 0.01) than athletes who were seronegative for both CMV and EBV (n = 31, 13 %). Conclusions: Previous coinfection with CMV and EBV might promote protective immune surveillance to lower the risk of URTI. Further research is required to clarify why previous CMV and EBV infection reduces the incidence of URTI.