Epidemiological map of CD, and question for Canadians

[Mark in Seattle]

Here is a map of the CD frequency globally. I wanted to look into this because I'm always intrigued by how geographies can be so different in terms of incidence/prevalence, and I figure there must be some good clues there if anyone wanted to seriously research it.

So if you want to check out this color coded map on page 4 of this link:

http://biologie.univ-mrs.fr/upload/p87/Economou.pdf

And you may notice the east-west gradient in Canada. The line is drawn between Manitoba and Ontario. Western Canada is red, which is the densest population of CD, while eastern Canada is green, which is the second from the lowest color coding on this map. So I'm just throwing out this question for Canadians if there are any theories as to how east/west differ which might explain the difference in CD incidence.

I think it's also interesting to note how the map turns red again in what I am perceiving as New Brunswick.

If it were me (I'm just a layman conjecturing...but hey), I'd like to go to a place on the map that is blue (lowest incidence), like Sudan for example, and see what is different with the folks that have CD compared to the general population. I think it's too late to try to ascertain anything by studying folks in the yellow and red zones.

I personally get a bit irked when I read so many epidemiology studies because it seems that all of the researchers do a somewhat cursory level job of researching and don't really put a lot of boots on the ground to really see what the true environmental variables are that are causing this.

 

[kiny]

They put forth 2 explanations in the text under discussion why it's primarily seen in the West.

Either it's MAP, and it coincides with the use of milk (there is another study that actually links places with more lactose intolerance to increased crohn)

Or it's because the West is more hygenic and children are exposed much later to bacteria in life than in other places. (this doesn't exclude MAP)