The newest edition of Parasitic Diseases is available in PDF form (officially) for free from http://www.parasiteswithoutborders.com/ ... h-edition/
You can also purchase a hardcopy from the same location (which I'll be doing soon).
Two of the authors on the book are also hosts on the podcast "This Week In Parasitism", which is one of several podcasts run by the same group. I highly recommend them if you're interested in microbiology. You can find all the podcasts (and several others) on: http://www.microbe.tv/science-shows/
Figured this would be an appropriate place to share these since I assume they're a common interest for anyone reading here. XD