I have two bookshelves full of books that I regularly consult on travel medicine issues. Obviously, it's impractical for anyone to carry these heavy resources, and therefore it is lucky that there is a skillful synopsis available by Stephen Bezruchka. Dr. Bezruchka has spent a lot of his adult life in developing countries, mostly Nepal. He has distilled the most basic information that might confront the international traveller into a book that is the same size as your passport. The tone is reassuring and authoratative. You will want to read the pre-travel information before you go, but you may not look at the rest of it--until you need it. I think this is the lightest, most useful resource available to travelers.