Flaming Vomit

Originating from Brionne, Bretonnia, the sufferers of Flaming Vomit have a high fever and produce copious quantities of bright red vomit. It is a brighter red than blood, though doctors suspect that blood is a major constituent. After three days, the sufferers start to feel very cold, although they still have a fever and demand fires to keep them warm. These fires must be ever larger as the disease progresses.

Source

 * Warhammer Fantasy RPG 2nd ED -- Knights of the Grail (pg. 62).