One of the songs in particular, "Virus", was written after Björk learned about "zombie snails" on YouTube. It has nothing to do with real viruses, though (Disclaimer: I haven't heard the album yet so I can't say if the music is any good). These snails are parasitized by a trematode worm called Leucochloridium paradoxum, which you can see in the photo below.
|Snail infected with Leucochloridium paradoxum in its eyestalk.|
Find out more about the sneaky life cycle of this worm from this article on Wired magazine, or read the Wikipedia article, or just watch the video that inspired Björk: