The Festering Death, also known as simply the Festering, was a horrific plague which ravaged England prior to the 19th century. It caused severe putrefaction of the skin and bodily organs, and also drove its victims insane, causing them to hallucinate. It spread via physical touch. Consequently, victims of the Festering had a heightened sexual appetite which drove them to commit rape, infecting other people.
Unique among diseases, the Festering Death lived on after its victims' deaths in the form of semi-sapient flesh-eating ulcers. The illness could remain alive for centuries, and was vulnerable only to fire. The disease was almost totally wiped out in the British Isles before the coming of the 20th century because the victims were almost always burned. As a result, it was an almost totally unknown disease even to modern day experts.
One isolated case of Festering Death survived into the 20th century however. In the town of Garth, during the early years of the disease's notoriety, before people knew to burn its victims, a forester named Tabor became infected and was hanged and then buried. In modern times, workers drilling a well for Mike and Holly Mannion unearthed Tabor's remains, and with them, the Festering. Several residents of Garth, including the Mannions, fell prey to the Festering before Dr. Gerald Williamson burned up the original site of the infection in the well.