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Abstract

We are pleased by the precise review of our paper by Drs Levy and Plevy. Furthermore, we are delighted by the careful comparison between the results of our study and the case-control studies by Amre et al (Am J Gastroenterol 2006;101:1005–1011) and Bernstein et al (Am J Gastroenterol 2006;101:993–1002).As stated by the authors, some disparities between the 3 studies have to be highlighted. In addition to those mentioned by Levy and Plevy, some extra points might be worthwhile mentioning to explain the different findings. Our study, as well as the study by Amre et al, included pediatric cases of inflammatory bowel disease (IBD), the study by Bernstein et al focused on prevalent adult cases. Furthermore, Amre et al studied childhood pet contact only. Owing to the urban setting, they did not take farm animal contact into account, which seems to be more important than pet contact in the protection from allergic diseases (Lancet 2001;358:1129–1133).Another important point in the protective effect of farm animal contact on the development of respiratory allergies seems to be the timing of exposure. This aspect was not included in the study by Bernstein et al, most likely because of potential recall bias (participants were between 18 and 50 years of age at the time of the study). Because eating patterns are likely to change after diagnosis, the protective effect of having ever drunk unpasteurized milk on IBD seen in the study by Bernstein et al might be a result of this source of bias.What next? A prospective cohort of children at risk for IBD in rural and urban environments as suggested by Levy and Plevy would without any doubt be very helpful to disentangle the role of farm environments on IBD. In this context, we should not forget about the different genetic makeup that might always contribute to dissimilar epidemiologic findings in different populations. Therefore, in addition to research focusing on gene–environment interactions in industrialized countries, investigations in countries in economic and epidemiologic transition where the prevalence of IBD is currently on the rise are needed. This may help to derive strategies that may more effectively prevent, diagnose, and treat these diseases, not only in European and North American populations, but also in emerging nations. We are pleased by the precise review of our paper by Drs Levy and Plevy. Furthermore, we are delighted by the careful comparison between the results of our study and the case-control studies by Amre et al (Am J Gastroenterol 2006;101:1005–1011) and Bernstein et al (Am J Gastroenterol 2006;101:993–1002). As stated by the authors, some disparities between the 3 studies have to be highlighted. In addition to those mentioned by Levy and Plevy, some extra points might be worthwhile mentioning to explain the different findings. Our study, as well as the study by Amre et al, included pediatric cases of inflammatory bowel disease (IBD), the study by Bernstein et al focused on prevalent adult cases. Furthermore, Amre et al studied childhood pet contact only. Owing to the urban setting, they did not take farm animal contact into account, which seems to be more important than pet contact in the protection from allergic diseases (Lancet 2001;358:1129–1133). Another important point in the protective effect of farm animal contact on the development of respiratory allergies seems to be the timing of exposure. This aspect was not included in the study by Bernstein et al, most likely because of potential recall bias (participants were between 18 and 50 years of age at the time of the study). Because eating patterns are likely to change after diagnosis, the protective effect of having ever drunk unpasteurized milk on IBD seen in the study by Bernstein et al might be a result of this source of bias. What next? A prospective cohort of children at risk for IBD in rural and urban environments as suggested by Levy and Plevy would without any doubt be very helpful to disentangle the role of farm environments on IBD. In this context, we should not forget about the different genetic makeup that might always contribute to dissimilar epidemiologic findings in different populations. Therefore, in addition to research focusing on gene–environment interactions in industrialized countries, investigations in countries in economic and epidemiologic transition where the prevalence of IBD is currently on the rise are needed. This may help to derive strategies that may more effectively prevent, diagnose, and treat these diseases, not only in European and North American populations, but also in emerging nations. Farm Animals and Inflammatory Bowel Disease: Old MacDonald Had Poor HygieneGastroenterologyVol. 134Issue 3PreviewRadon K, Windstetter D, Poluda AL, et al. (Unit for Occupational and Environmental Epidemiology & NetTeaching, Institute and Outpatient Clinic for Occupational and Environmental Medicine, Munich, Germany). Contact with farm animals in early life and juvenile inflammatory bowel disease: a case-control study. Pediatrics 2007;120:354–361. Full-Text PDF