Why is nutritional oedema (kwashiorkor) localized in specific area?

In my short experiences, when I was in Bangladesh, which has high underweight rate of u5 Asia, and saw that kwashiokor was less shown than African countries that I ever visited. I think that the one of reasons is related to the kind of food that people daily consume. Dal (beans) is consumed daily in Bangla although its amount is small; that is, children has more opportunity not to be kwashiokar. However, it needs more evidence based research.

Kiros, you are correct. When I look at the distribution of kwash in surveys it always follows a negative binomial distribution between clusters (showing pocketing of kwash in certain clusters) whereas marasmus follows a poisson distribution showing that it is randomly distributed in an area. So yes, I have the statistical proof that it occurs in certain areas - and these can be very small - like one village, whereas the neighbouring villages do not have kwash. It is clearly an environmental factor. But we are not sure why as yet. I have noticed that the prevalence tends to be high where there is deeply red soil and a reasonably heavy rainfall (with staples of maize, cassava, banana, rice, enset, yam). I suspect that it is related to mineral nutrition but have no firm evidence except some indication that Se is implicated. It is a fascinating question - with no answer at the moment. Cheers Mike Golden