The geoepidemiology of autoimmune intestinal diseases

Inflammatory bowel diseases (IBD) are chronic diseases of the intestinal tract which principally are composed of ulcerative colitis (UC) and Crohn's disease (CD). The prevalence and incidence of both forms of IBD have historically been higher in developed countries with decreasing North-South gradient. However, more recent evidence demonstrate changing demographics as countries become more developed and immigration increases from underdeveloped countries to developed countries. Typically these changes are marked by an increase in ulcerative colitis followed by an increase in CD. Thus, most if not all human populations appear to be susceptible to IBD under certain environmental influences. Several hypothesis have been advanced to explain these changing demographics including alterations in the bowel microflora, but direct experimental evidence is lacking in most cases. Celiac disease or gluten-sensitive enteropathy is a related inflammatory condition which is induced in susceptible individuals when exposed to gluten-containing foods. Similarly, the prevalence of celiac disease is increasing as the consumption of gluten-containing foods is increasing worldwide.