more at link... but this is the point https://www.thesun.co.uk/news/53517...million-in-just-five-years-scientists-reveal/ ... The cocoliztli epidemic – attributed to one or two illnesses collectively - caused millions of deaths in the New Spain territory of Mexico in the 16th century. Although the cause for the epidemic remains unknown, theories suggest it could have been a deadly viral haemorrhagic fever exacerbated by the worst droughts to hit the region in 500 years. Heavy downpours that followed the drought saw an increase in populations of the Vesper mouse – a carrier of haemorrhagic fever. According to physician Francisco Hernandez, symptoms included high fever, severe headache, vertigo, black tongue, dark urine, dysentery, severe abdominal pain, head and neck nodules, jaundice and profuse bleeding from the nose, eyes, and mouth. Death frequently occurred in 3 to 4 days.