Bah, what are you, 12 year olds?
Oh wait, this is the internet. Of course you are.
While I do not fear these conditions per se, I have looked into them more than most (and that doesn't mean I've watched every movie, but actual research)
First Lycanthropy, Most of you probaly consider it to just be getting hairy and losing your mind at the full of the moon, and being immune to anything less than silver bullets or wolfbane. Not quite. For the most part you can be wounded normaly and the wound will show in both forms. There is also the fact that according to most ledgends, they MUST kill to survive during such transformations. wether due to having to eat the flesh or drink the blood of a human victem. Often they are considered to perish at the Touch of silver, not just from being dealt a mortal blow from a weapon crafted of it. This leads to it being a rather regretable condition, best solved quickly.
Another interesting fact about werewolves of ledgend, is that if not slain by a weapon of silver they would rise again as a vampire...
Vampires you must remember are undead, they are no longer the people they appear to be, and quite honnestly I am offended by the recent flood of vampire romance entering the mainstream. These creatures are in most older tales bear the hallmarks of being corrupted by disease, the hungry dead lusting for blood and all that. Yet in modern times they have been turned into mesmerising seductors, suddenly considered to be "cool". Creatures that slowly drain the life force out of people until they die are currently being portraid as "not so bad people" and it irks me.
And then there is the most generic type of living dead, or "Zombie" if you prefer (Actualy a misnomer in this case, zombies being undead servants being raised by magic, while infectious undead tend to be far less intentional). These infected have a tendance to quickly degenerate to a point of non-sentience and rot in a bizzare fashion (in most cases they appear to dessicate rather than bloat as one whould expect, as if only the surface tissue was affected. but I digress, it would be a condition where if you were infected then a dramatic act of self sacrifice would most likely be your best way out (at least for the remaining uninfected around you).
to quote the last human, "better dead than smeg"