Dear Priya, [Priya Anaokar, Jamaica http://www.hifa.org/dgroups-rss/prevalence-chronic-diseases ]
Have you looked at the global burden of disease (GBD) publications and web site?
Your message did not say what sources had been tried, if any, nor the results of that research. My experience has been - both as a generall and specific-focus medical librarian - that information on even a singlee disease will vary widely in terms of disease and geographic area and currency.
I am part of the GBD vision expert group. So I know the challenges in uncovering the most current and useful information for a few diseases which might be included in your definition of chronic.
So all that I can say is that the GBD publications, which I believe are all OA, and the GBD atlas, are worth spending time looking at and understanding. The GBD panels do not do epidemiological prevalence and incidence research; they search out the work which has been done, extract and organize the information. There may be more up to date data for specific diseases in some parts or all of the region you are interested in. But if I were asked as a librarian I would have to clarify what diseases, what work had been done already using what resources, etc. I don't know, for instance, if you are interested in psoriasis, hyperlipidemua, glaucoma...all systems? All diseases classed as chronic, all populations?
Pamela C. Sieving
Sieving Information Solutions
HIFA profile: Pamela Sieving is a special volunteer at the National Eye Institute/National Institutes of Health, and an independent consultant in biomedical information access; she works primarily in the vision community to increase access to information needed to preserve and restore vision. pamsieving AT gmail.com