Bacteria as biological weapons: The war of the flea

Since ancient times, centuries before the term ‘biological warfare’ had been coined and before Pasteur and Koch had developed the germ theory of disease, bacteria have been used as weapons. For example; in 1343 an invading Mongol army threw plague-infested bodies over the walls of a besieged city in Northern Italy to cause outbreaks of the Black Death (plague)1. It was common practice to put animal carcasses into wells or watercourses to pollute a water supply.