Aztecs were wiped out by horror ‘eye-bleeding’ disease that killed 15million in just five years, scientists reveal
Experts say an epidemic called cocoliztli was to blame after finding DNA evidence on the teeth of long-dead victims
THE Aztecs were wiped out by a horror disease that caused them to bleed from the eyes, mouth and nose, experts have revealed.
Scientists say as many as 15 million people - an estimated 80 per cent of population - were killed when an epidemic known as cocoliztli swept Mexico's Aztec nation in 1545.
The word means “pestilence” in the Aztec Nahuatl language.
Its cause, however, has been in question for nearly 500 years.
On Monday, scientists swept aside smallpox, measles, mumps, and influenza as likely suspects, fingering a typhoid-like “enteric fever” for which they found DNA evidence on the teeth of long-dead victims, reports news.com.au.
Ashild Vagene, of the University of Tuebingen in Germany, said: “The 1545-50 cocoliztli was one of many epidemics to affect Mexico after the arrival of Europeans, but was specifically the second of three epidemics that were most devastating and led to the largest number of human losses.
“The cause of this epidemic has been debated for over a century by historians and now we are able to provide direct evidence through the use of ancient DNA to contribute to a longstanding historical question."
Vagene co-authored a study published in the science journal Nature Ecology & Evolution.
The cocoliztli outbreak is considered one of the deadliest epidemics in human history, approaching the “Black Death” bubonic plague that felled some 25 million people in western Europe in the 14th century — about half the regional population.
Analysing DNA extracted from 29 skeletons buried in a cocoliztli cemetery, scientists found traces of the salmonella enterica bacterium, of the Paratyphi C variety.
KILLER DISEASE What is cocoliztli?
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.
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It is known to cause enteric fever, of which typhoid is an example.
The Mexican subtype rarely causes human infection today.
Many salmonella strains spread via infected food or water, and may have travelled to Mexico with domesticated animals brought by the Spanish, the research team said.
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