The effect of tonsillectomy on John Cunningham virus serological status in multiple sclerosis patients: A retrospective case–control study

Tonsils are believed to be the initial site of the John Cunningham virus (JCV) infection. The long-term effect of childhood tonsillectomy on JCV status in multiple sclerosis (MS) patients has not been investigated. In this retrospective case–control study, we analyzed data of 144 JCV seropositive cases and 82 JCV seronegative controls from three outpatient MS clinics in the United States. Early tonsillectomy (before the age of 8) was reported among 8 (5.56%) JCV seropositive subjects and 19 (23.17%) controls. Early tonsillectomy was associated with JCV negative status (adjusted odds ratio = 5.39, 95% confidence interval = 2.13–13.62, p < 0.001) independent of age and gender.