Seasonal variation of enteric infections and inflammatory bowel disease.

Background: The time trends of inflammatory bowel disease are characterized by short-term variations that affect Crohn's disease and ulcerative colitis alike. The aim of the present study was to test whether these variations might be related to exacerbations of inflammatory bowel disease secondary to superimposed gastrointestinal infection.
Methods: The Hospital Episode Statistics (HES) comprises a data set of all patients admitted to hospitals throughout England, which includes inpatients and day cases. This data set was used to analyze the monthly variations in all hospital admissions for Crohn's disease (ICD10 code K50), ulcerative colitis (K51), bacterial intestinal infections (A04), viral intestinal infections (A08), diarrhea and infectious gastroenteritis (A09), upper respiratory infections (J06), pneumonia secondary to unspecified organism (J18), and unspecified acute lower respiratory infection (J22).
Results: The temporal analysis revealed similar monthly fluctuations of hospital admissions for Crohn's disease, ulcerative colitis, and bacterial intestinal infections. Viral intestinal infections and infectious gastroenteritis were characterized by different seasonal variations that showed no relationship with any of the fluctuations of inflammatory bowel disease or bacterial intestinal infections. Similarly, respiratory infections resulted in marked cyclical variations in hospital admissions unrelated to any changes in inflammatory bowel disease or enteric infections.
Conclusions: The similarity in the time trends of Crohn's disease, ulcerative colitis, and bacterial intestinal infections suggests that superinfection by intestinal bacteria are responsible for the fluctuations in hospital admissions for inflammatory bowel disease.