This week's (August 6, 2008) issue of The New Yorker magazine has an article by Jerome Groopman on "Superbugs," which I found helpful for getting caught up on the use of antibiotics and the rise of antibiotic resistant bacteria in recent years.

I can also recommend "Flu: The Story Of The Great Influenza Pandemic" by Gina Kolata.

Thanks for the link, Blast, to the article re: bacterial infections and the 1918 flu epidemic.