Creeping Buboes

What begins as a reddish sore in a tender area spreads all over the body in a matter of hours. After a day, the buboes burst, and drip a foul-smelling, black bile. This is an old disease, and some believe it was part, if not all, of the terrible plague that spread through the Empire in the twelfth century. This disease spreads through fleabites.

Source

 * Warhammer Fantasy RPG 2nd ED -- Tome of Corruption (pg. 48).