Ergotism is a condition that arises from the consumption of grains contaminated with a fungus called Claviceps purpurea. This fungus infects cereal crops, particularly rye, and produces toxic compounds known as ergot alkaloids.

When grains infected with Claviceps purpurea are consumed, the alkaloids present in the fungus can cause various symptoms and health effects in humans and animals. There are two main types of ergotism: gangrenous and convulsive.

Gangrenous ergotism occurs when the alkaloids constrict blood vessels, leading to reduced blood flow and tissue death (gangrene). This can result in symptoms such as cold and painful extremities, numbness, and eventually gangrene.

Convulsive ergotism is characterized by neurological symptoms, including hallucinations, muscle spasms, seizures, and mental disturbances.

It`s important to note that ergotism is rare in modern times due to improved agricultural practices and food safety measures. However, historically, outbreaks of ergotism have been associated with the consumption of contaminated grains, especially during times when the fungus was more prevalent or when grain storage conditions were inadequate.

In summary, ergotism is caused by the consumption of grains contaminated with the fungus Claviceps purpurea, and it is not related to rotting vegetables, contaminated water, or stale cooked food.