Bilemaw!

Blech.

Here's a description too for extra nerd points:

Bilemaws are a foul species of dragon that some believe to be responsible for virulent outbreaks of plague. They exude an awful nauseating smell from their mouths and through vents along their necks. Usually the stink may signal the arrival of a bilemaw to the wary. While unpleasant, breathing the stench given off from a bilemaw isn't lethal. The real danger of dealing with bilemaws results from their foul dripping mouths. While flying overhead cities and villages their jaws will drip infectious gobs of offal, literally causing a rain of plague. Anyone unfortunate enough to be bitten by a bilemaw and escape will soon find their body rife with infection. Any attempt by the victim to seek refuge and relief among their friends and family will sadly result in the spread of the plague.