The Association between Childhood Environmental Exposures and the Subsequent Development of Crohn's Disease in the Western Cape, South Africa

Background: Environmental factors during childhood are thought to play a role in the aetiolgy of Crohn's Disease (CD). However the association between age at time of exposure and the subsequent development of CD in South Africa is unknown. Methods: A case control study of all consecutive CD patients seen at 2 large inflammatory bowel disease (IBD) referral centers in the Western Cape, South Africa between September 2011 and January 2013 was performed. Numerous environmental exposures during 3 age intervals; 0-5, 6-10 and 11-18 years were extracted using an investigator administered questionnaire. An agreement analysis was performed to determine the reliability of questionnaire data for all the relevant variables. Results: This study included 194 CD patients and 213 controls. On multiple logistic regression analysis, a number of childhood environmental exposures during the 3 age interval were significantly associated with the risk of developing CD. During the age interval 6-10 years, never having had consumed unpasteurized milk (OR=5.84; 95% CI, 2.73-13.53) and never having a donkey, horse, sheep or cow on the property (OR=2.48; 95% CI, 1.09-5.98) significantly increased the risk of developing future CD. During the age interval 11-18 years, an independent risk-association was identified for; never having consumed unpasteurized milk (OR=2.60; 95% CI, 1.17-6.10) and second-hand cigarette smoke exposure (OR=1.93; 95% CI, 1.13-3.35). Conclusion: This study demonstrates that both limited microbial exposures and exposure to second-hand cigarette smoke during childhood is associated with future development of CD.