Peeps by Scott Westerfeld
In Peeps vampirism is a parasitic sexually transmitted disease. Once infected with Echinococcus cannibillus, you turn into a vampiric monster who eschews sunnlight in favor of hordes of rats or you become a carrier like the novel's protagonist. Cal has night-vision, superhuman strength, and a ravenous craving for sex - after all, the parasite needs its carriers to spread.
My friend Jessica originally advised me against reading Peeps. She didn't think I'd care for the parasite descriptions that begin open each chapter. She was right, but fortunately those sections are consistent enough to make them easy to skip over them without missing out on any of the text of the main story (I'll admit that I stopped forcing myself to read them at around the halfway point).
Parasites aside, I thought Peeps was OK. While I really like Westerfeld, this one was not one of my favorites. It took me a week and a half to read it (normally I'd be able to read it in a day or two) because it was never my first choice when I sat down to read. I didn't find the storyline particularly compelling (though it did get better for me in the last quarter). I did like Westerfeld's historical and biological explanation of vampirism, though.