COCOLIZTLI: THE LOST EPIDEMIC
- Genaro Pimienta
- Jan 7
- 6 min read
Updated: Jan 9
THE GREAT SICKNESS
Centuries ago, a deadly epidemic swept through Mesoamerica. Those who lived through it, called this malady cocoliztli, which means sickness or pestilence in the Nahuatl language.
It was a hemorrhagic fever. One which in the spring of 1545, appeared out of nowhere in central Mexico's highlands. Cocoliztli spread with the wind, stopping only because the roads ended. Sonora to the north. Guatemala in the far south.
Estimates from population censuses put the death toll at ~80% in a span of three years (1545-1548).
In 1576, cocoliztli struck again, taking in its wake ~50% of the souls who had survived the 1545 epidemic.
Cocoliztli presumably died-out in 1815. But before that, it recurred 12 times during the 17-19th centuries.
THE SYMPTOMS
The sick died in 3 to 4 days after the first signs of malady appeared.
The combination of symptoms were unlike any of the plagues documented back then.
Fever with hemorrhage from ears, eyes, mouth, and nose
Liver enlargement and jaundice
Convulsions and delirium
Commissioned by the Spanish Royal Crown, Dr Francisco Hernandez de Toledo (the Viceroy's Chief Physician), performed autopsies on the dead from cocolizlti infection.
In his detailed medical report to the Spanish Royal Crown, Francisco Hernandez used the word cocoliztli. And in doing so, he pointed out that cocoliztli was different from anything his eyes had ever seen.
THE AFTERMATH
It was all empty towns. The dead were so many, that they laid unburied on the streets.
Those who survived could barely recover. Missionaries from all congregations tried to help, but were at a loss. And in helping, some of them, like Friar Bernardino de Sahagun, got infected too and passed away.
But before that happened, Friar Bernardino de Sahagun had been combining his evangelization efforts with meticulous anthropological studies of the Mesoamerican cultures.
Urged by the need to preserve their traditions, Mesoamericans took to using codexes. It was in codexes that they wrote about their ways and beliefs, and about their post-Contact (with Europe) experiences.
Many accounts of the cocoliztli outbreaks from 1545 and 1576 are available in codex format. One example is the Codex Telleriano Remensis shown below.
The outbreak in 1545 documented in the Codex Telleriano Remensis. The text in the image reads: Left:“Yesterday big trees broken." Right:"Year 1544 and 1545 great mortality amongst indians."
THE CONTEXT
Long hidden in the wilderness, but one day thirsty and hungry, cocoliztli went for a walk.
By 1545, many in Mesoamerica had been forcefully relocated by the Spanish to densely packed agricultural communities. In these places, people co-existed in close proximity with domesticated and wild animals.
These poor living conditions were heightened by a long-lasting megadrought, which led to insufferable famine. A dire scenario of this type may have laid out the conditions for an epidemic outbreak.
Three plausible consequences:
European livestock (cows, goats, hens, horses, and pigs) put in farms for Mesoamericans to take care of, became a flash point for zoonotic disease outbreaks.
The severe drought, which had triggered a famine, may have prompted Mesoamericans to eat wild animals they otherwise would have not consumed.
Cocoliztli, which appeared right after an unusual rain in the midst of the drought, may have prompted an influx of wild animals into human settlements in search for food and water.
THE BACTERIA
In a burial ground, which dates back to the cocoliztli epidemic, the teeth of the dead who lay there to rest in the afterlife, keep a secret.
A study published in 2018, which leveraged metagenomics tools, reported the first link between a pathogenic bacteria—Salmonella enterica subsp. enterica serovar Paratyphi C— and the 1576 cocoliztli epidemic.
Three caveats in this study should be pointed out:
From the 28 samples analyzed, only 8 have Salmonella enterica subsp. enterica serovar Paratyphi C
The metagenomics approach used is limited to bacteria and DNA viruses, leaving RNA viruses unexplored
While inconclusive, this study offers a glimpse into what may have caused the wave of cocoliztli outbreaks in Mesoamerica.
THE VIRUS
In the riddle that cocoliztli appears to be, a loose knot stands out.
The microbe linked to cocoliztli, while still elusive, can only be one which causes hemorrhagic fever. This fact alone limits the possibilities to an RNA virus.
The hypothesis, which proposes that cocoliztli was caused by a hemorrhagic RNA virus, is substantiated by a series of studies, published in the early 2000s.
Rich in climatological, demographic and ethnographic information, these studies offer a glimpse into the circumstances surrounding the cocoliztli outbreaks.
Centerfold to these circumstances is a yet unidentified zoonotic reservoir (possibly a rodent) from which the pathogen linked to cocoliztle jumped to humans.
Along this train of thought, the year 1967 was one in which a surge of wild mice in towns of Chiapas, Mexico, coincided with a hemorrhagic fever outbreak.
CONCLUSION
In times of constant pandemic outbreaks, worldwide epidemiological surveillance will remain incomplete until we know what caused the cocoliztli epidemics.
The rapid dissemination of the cocoliztli outbreaks (thousands of kilometers in a few weeks) points to a viral, rather than a bacterial etiology.
Salmonella enterica subsp. enterica serovar Paratyphi C, which is not known to cause hemorrhagic fever, may be a false lead, even if it was identified in the teeth of cocoliztli victims.
The results from the publication in Nature Ecology and Evolution that linked Salmonella enterica subsp. enterica serovar Paratyphi C to the cocoliztli epidemics, were misconstrued by some news outlets.
Prompted by this, the authors from the Salmonella paper clarified the meaning of their findings in Nature Springer's Behind the Paper channel.
"We appreciate the media coverage our work has received, though we wish to clarify two points widely mentioned that are contrary to our research design and conclusions:
Our analysis has focused on a Mixtec population as opposed to a Central Mexican Aztec population.
We believe enteric fever should be considered a candidate for the 1545 cocoliztli epidemic, but we do not assert that it was the definitive or sole cause."
"While these data demonstrate the presence of S. enterica Paratyphi C (enteric fever) at Teposcolula-Yucundaa during the 1545 epidemic, we cannot comment on its presence in other places around Mexico or whether it was the sole cause of the epidemic. Our detection method was limited to bacteria and DNA viruses, which represent a subset of pathogenic organisms capable of epidemic mortality."
FURTHER READING
1.
Goldsmith, R. S. & Shields, K. P. Epidemic in southern Mexico of disease resembling virus haemorrhagic fevers. Lancet (London, England) 2, 151–4 (1971).
2.
Elsa Malvido and Carlos Viesca. La epidemia de cocoliztli de 1576. https://www.estudioshistoricos.inah.gob.mx/revistaHistorias/wp-content/uploads/historias_11_24-33.pdf 26–33 (1985).
3.
Marr, J. S. & Kiracofe, J. B. Was the huey cocoliztli a haemorrhagic fever? Medical history 44, 341–62 (2000).
4.
Acuna-Soto, R., Romero, L. C. & Maguire, J. H. Large epidemics of hemorrhagic fevers in Mexico 1545-1815. The American journal of tropical medicine and hygiene 62, 733–9 (2000).
5.
Acuna-Soto, R., Stahle, D. W., Cleaveland, M. K. & Therrell, M. D. Megadrought and megadeath in 16th century Mexico. Emerging infectious diseases 8, 360–2 (2002).
6.
Acuna-Soto, R., Stahle, D. W., Therrell, M. D., Griffin, R. D. & Cleaveland, M. K. When half of the population died: the epidemic of hemorrhagic fevers of 1576 in Mexico. FEMS microbiology letters 240, 1–5 (2004).
7.
Acuna-Soto, R., Stahle, D. W., Therrell, M. D., Gomez Chavez, S. & Cleaveland, M. K. Drought, epidemic disease, and the fall of classic period cultures in Mesoamerica (AD 750-950). Hemorrhagic fevers as a cause of massive population loss. Medical hypotheses 65, 405–9 (2005).
8.
Cajimat, M. N. B., Milazzo, M. L., Bradley, R. D. & Fulhorst, C. F. Ocozocoautla de espinosa virus and hemorrhagic fever, Mexico. Emerging infectious diseases 18, 401–5 (2012).
9.
Vågene, Å. J. et al. Salmonella enterica genomes from victims of a major sixteenth-century epidemic in Mexico. Nature ecology & evolution 2, 520–528 (2018).
10.
Christina Warinner. Mixtecs, Aztecs and the great cocoliztli epidemic of AD 1545-1550. https://communities.springernature.com/posts/mixtecs-aztecs-and-the-great-cocoliztli-epidemic-of-ad-1545-1550 (2018).
GPR 01/07/2025
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