Peeps by Westerfeld

Before there was the ruckus over Twilight and all other things vampire, there was Peeps. The book offers a fresh and interesting view of vampires. According to Westerfeld, vampirism is a fluid-borne disease with interesting side-effects, like an aversion to anything or anyone you used to love. (Hence, why vampires hate crosses and garlic - some of them used to be good Italian Catholics).

Because these monsters are a product of science rather than evil, there's a good deal of cool information about diseases, parasites, and other biology. The story follows Cal, a kid who is positive for the disease but doesn't have any of the unpleasant, people-eating symptoms. He works with a secret branch of the government to track down active vampires, contain them, and treat them.

The book is a bit mature (the parasite is passed through *ahem* sexual contact) but it never gets too lurid. Due to the cannibalism and sensuality, it's probably not a book for the squeemish, but it's still a good story. This book has a sequel, called The Last Days. Please do not read it, as it is horrible.