After I read this, I thought I should become an epidemiologist.
Though it was classified under the children's section at my local library, I was intrigued by both the cover, the description, and the title. I checked it out and read it; it contains summaries, drawings, history, stories, and explanations of many highly infectious diseases that have plagued man throughout history--six or seven, I believe. Included are: tuberculosis, leprosy, cholera, bubonic plague, AIDS, smallpox, and malaria. Before I read this, the basis of my knowledge of smallpox was that it is mostly gone, with the exception of a few lab samples around the world. Now I know how the vaccination was developed, as well as its spread and symptoms.
If diseases are something even slightly interesting to you, this is the book I would begin with.