Diseases Transmitted by Man's Worst Friend: the Rat.

Historically, the rat has been considered a scourge to mankind, for example, rats infected with the plague bacillus that caused the Black Death, which accounted for millions of deaths in Europe during the Middle Ages. At least three pandemics (in the 5th and 6th, 8th through 14th, and 19th through 21st centuries) of plague ravaged civilizations, and the disease undoubtedly plagued humankind prior to recorded history. Also, numerous other diseases are spread to humans by rats; thus, a quote from Hans Zinsser's text Rats, Lice, and History, "Man and rat will always be pitted against each other as implacable enemies," conveys the general revulsion that society holds for the wild rat.