Amoeba, Death-knell
by Sean MeaneySize: Microscopic; Environment: Equatorial Lakes and Rivers; Frequency: Rare
Stats: HD: 1hp; AC: -1; MV/Swim: 3'(1'); At: bite; DA: special; SA: Normal Human; NA: River Swarm (10d100)/Lake Nest (1d100 per square ft) ML 12; INT: 1; TT: NIL; XP:6
Description: This tiny little bugger lives in some lakes and will swim up the nose into the brain unnoticed where it will slowly eat the brain. Victims loose one point of intelligence(01-76)/Wisdom(77-90)/Charisma(91-100) every week until death (one stat is reduced to zero). Only a wish or regenerate spell can cure the damage. Only a Wish can remove the creature from a victim.
Source: Can we stop the spread of brain-eating amoebas that killed two children in Minnesota?