Crisms
This is an unspecified and undescribed disease, possibly spread by Walruses, which has terminal consequences. The first Mr Proust died of Crisms, leaving his wife and his sons to run the Boffo Novelty and Joke Shop on Tenth Egg Street.
A brother of lady Sybil (wife of Sam Vimes) "fell victim to the outbreak of crisms, poor lad." (Quote from Snuff.)