A United Press article notes a recent study showing Canada to have one of the highest IBD rates in the world. An extract from the study's summary reads:
Based on our data we believe that there are currently approximately 170,000 (or approximately 1 in 180) Canadians with IBD. In areas of high incidence such as Europe, it has been estimated that as many as 1 in 100 people will develop IBD in their lifetime. Furthermore, our data suggest that incidence rates across the country, except for BC [British Columbia], are among the highest in the world, not just in MB [Manitoba]. Extrapolating our data to the United States suggests that as many as 1.5 million Americans have IBD. However, as discussed above, including accounting for potential disparities in incidence rate by geography (on a North-South basis), this extrapolation would need to be verified by careful epidemiological studies in the United States.
source: The Epidemiology of Inflammatory Bowel Disease in Canada: A Population-Based Study. The American Journal of Gastroenterology Volume 101 Page 1559 - July 2006
Recent epidemiological studies of IBD continue to show surprisingly high incidence rates. For example, an October 2003 Wisconsin study showed "the highest pediatric IBD incidence reported in the world to date". This Wisconsin study also noted:
An equal IBD incidence occurred among all ethnic groups, and children from sparsely and densely populated counties were equally affected. The majority (89%) of new IBD diagnoses were nonfamilial. [bold added]
source: Epidemiologic and clinical characteristics of children with newly diagnosed inflammatory bowel disease in wisconsin: a statewide population-based study. The Journal of Pediatrics. Volume 143, Issue 4 , October 2003, Pages 525-531