I just finished "The Ghost Map", a book that covers a Cholera outbreak in 1854 London - and more importantly, the forensic footwork by Dr. John Snow and Rev. Henry Whitehead that traced the outbreak to a contaminated pump on Broad Street.
There's an interesting little epilogue as well, that catalogs the rise of urbanization in the world. Right now, roughly 50% of the world's population lives in urban areas, and if current trends continue, that will likely be 80% by the middle of this century. That's an unabashedly good thing, so far as the author is concerned, based on the fact that urban areas make many problems (transit, public health, sewage, etc) easier to deal with. He also lays out a few possible threats to that trend - a new plague of 1918 (or greater) proportions, nuclear terrorism - things of that nature. The epilogue is probably worthy of a whole separate book. In any case, I'd highly recommend this book - if nothing else, you'll learn how far urban health has come in the last century and a half.