12. Believed to be responsible for the deaths of approximately eighty percent of the Aztec people, “cocoliztli” killed tens of millions in the centuries following the Spanish arrival in the Americas
Spanning at least twelve outbreaks, including three major epidemics in the 16th century in the aftermath of Spanish arrival, “cocoliztli”, as the disease was termed by the native Aztecs, devastated the indigenous population of Mexico. First appearing in around 1520, the outbreak of 1545-1548, in particular, caused an immeasurable and fatal impact upon the Aztec civilization. Daily death tolls in the cities of Tlaxcala and Cholula ranged between 400-1,000 people, contributing to an estimated death toll of five to fifteen million people representing potentially as much as eighty to ninety percent of the indigenous population at this time.
Crucial to the reduction of the Aztec population from thirty million in 1519 to less than two million by 1700, the precise cause of the epidemic remains unknown. Major occurrences of “cocoliztli” typically appeared within two years of a major drought, lending credence to suggestions of a vermin-carried hemorrhagic fever. Symptoms, however, remain similar to many “Old World” diseases, including measles and typhus. Recent archaeological study has uncovered evidence of Salmonella enterica during the time of the outbreak, resulting in speculation that the epidemics might have been a unique concoction of immensely deadly afflictions.