St Anthony's fire

A different St Anthony, (the hermit) but the disease was caused by ergot fungus growing on rye.

from medievalistblog:

The Annales Xantenses reports that in the year 857 “a great plague of swollen blisters consumed the people by a loathsome rot, so that their limbs were loosened and fell off before death.” Ina Lipkowitz explains that the
victims suffered from hallucinations, insanity, vomiting, and gangrene of the hands and feet due to constriction of blood flow to the extremities. Those afflicted felt as if they were being burned at the stake as their fingers and toes split open and dropped off, one by one. A late medieval chronicler wrote of an “invisible fire that separated the flesh from the bones and consumed it.”It was said that 40 000 people in northern Germany were killed by the disease in the year 994. In the eleventh-century a group of lay people created an order to take care of people afflicted by the disease. They declared Saint Anthony of Egypt to be the patron saint of the order, and the disease became known as St.Anthony’s Fire. Ergotism is much rarer in the modern world, but outbreaks have occurred in less developed countries even in recent years