First use of biological warfare

The earliest documented incident of a biological agent being used in warfare is in the 6th century BC. The Assyrians, who lived in present-day Iraq, used rye ergot to poison enemy wells. The resulting effects were delusional and paranoid behaviour and even death amongst their attackers.

Ergot poisoning causes delusions, paranoia, seizures, twitching and cardiovascular problems that can lead to death.

Ergot is a fungus blight that causes ergot poisoning in crops.