" It was precisely the existence of trans-Eurasian trade routes that enabled the bacterium Yersinia pestis to kill so many fourteenth-century Europeans. Likewise, European expansion overseas, beginning roughly a century and a half later, led to the so-called Columbian Exchange: pathogens brought by Europeans devastated indigenous American populations; Europeans then brought back syphilis from the New World; and by shipping enslaved Africans to the Caribbean and the Americas, Europeans also brought malaria and yellow fever to those places. "

― Niall Ferguson , Doom: The Politics of Catastrophe