In the meantime, I offer this little goody you can use in OSRIC, although I'm sure you could use it in LL or S&W or whatever, too since there are really no stats to it. Enjoy.
(I'm being kind of funny here and saying things like "there is no save" and pointing out the "profuse sweating" part which just happened to me while on an important business phone call. Do with it what you want!)
Disease: Martian Death Flu
This disease can be spread by any humanoid creature. From Spring through Fall (3/4 of the year), the chance of encountering a creature with the Martian Death Flu is 1%. During the Winter, the chance of encountering a humanoid or demi-human creature with the Martian Death Flu is 5%.