Comment in Gastroenterology. 1999 Apr;116(4):988-9. Gastroenterology. 1999 Nov;117(5):1253-5. BACKGROUND & AIMS: Measles virus has been implicated in the etiology of both inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis. Subacute sclerosing panencephalitis (SSPE) is caused by atypical measles infection. This study investigated the patterns of infection that are risks for SSPE, early infection and a close temporal relationship between measles and another infection, as potential risks for IBD. METHODS: The data are from 7019 members of a nationally representative 1970 British Cohort Study. The ages of five childhood infections were recorded before onset of IBD symptoms. Diagnoses of IBD and insulin-dependent diabetes mellitus (IDDM), as a control disease, were identified by age 26 years. RESULTS: Mumps infection before age 2 years was a risk for ulcerative colitis (odds ratio, 25.12; 95% confidence interval, 6. 35-99.36). Measles and mumps infections in the same year of life were significantly associated with ulcerative colitis and Crohn's disease, with odds ratios of 7.47 (2.42-23.06) and 4.27 (1.24-14.46), but not with IDDM. These relationships are independent of each other as well as sex, social class at birth, household crowding in childhood, and family history of IBD. CONCLUSIONS: Atypical paramyxovirus infections in childhood may be risk factors for later IBD.