{
  "id": "cocoliztli-epidemic-of-1576",
  "type": "entity",
  "name": "The cocoliztli epidemic of 1576 and the record kept of it",
  "summary": "The epidemic that halved what was left of the indigenous population of central Mexico in two years, and the paper trail it left. The crown's protomédico wrote down the clinical picture; bodies were opened and the organ findings written up; tribute counts were taken in 1570 and 1580 on either side of it. Modern epidemiology still works from those documents and still cannot say what the disease was. The record is the contribution; the thing recorded is the catastrophe.",
  "locale": "en",
  "tags": [
    "medicine",
    "epidemiology",
    "new-spain",
    "demography",
    "science",
    "americas",
    "spanish-empire",
    "sixteenth-century"
  ],
  "relations": [
    {
      "rel": "related",
      "target": "quatro-libros-de-la-naturaleza-1615"
    },
    {
      "rel": "related",
      "target": "hospitals-of-the-indies"
    },
    {
      "rel": "related",
      "target": "protomedicato-de-las-indias"
    },
    {
      "rel": "related",
      "target": "columbian-exchange"
    },
    {
      "rel": "related",
      "target": "empires-violence-and-demography-compared"
    },
    {
      "rel": "related",
      "target": "orden-hospitalaria-de-san-juan-de-dios"
    },
    {
      "rel": "related",
      "target": "hospital-real-de-san-jose-de-los-naturales"
    },
    {
      "rel": "related",
      "target": "orden-de-la-caridad-de-san-hipolito"
    },
    {
      "rel": "related",
      "target": "pedro-lopez-hospital-de-la-epifania-1582"
    },
    {
      "rel": "related",
      "target": "epidemic-records-of-spanish-america"
    },
    {
      "rel": "related",
      "target": "colonial-records-as-a-climate-archive"
    },
    {
      "rel": "related",
      "target": "extramural-cemeteries-in-the-indies"
    },
    {
      "rel": "related",
      "target": "villalba-epidemiologia-espanola-1803"
    },
    {
      "rel": "related",
      "target": "cacao-out-of-the-americas"
    },
    {
      "rel": "related",
      "target": "cisneros-sitio-naturaleza-y-propriedades-1618"
    },
    {
      "rel": "related",
      "target": "annals-of-the-cakchiquels"
    }
  ],
  "questions": [
    "What was cocoliztli and what caused the 1576 epidemic in Mexico?",
    "How many people died in the cocoliztli epidemic of 1576?",
    "Who wrote down the symptoms of cocoliztli?",
    "Were autopsies performed during the 1576 epidemic in Mexico?",
    "How do historians know the scale of the sixteenth-century population collapse in Mexico?",
    "Was cocoliztli an Old World disease or an American one?"
  ],
  "claims": [
    {
      "id": "c1",
      "text": "The scale is measurable because the colonial administration counted people for tax on either side of the epidemic, and the two counts can be set against each other. Acuña-Soto and colleagues retrieved all the available data from the censuses of 1570 and 1579-1580, obtaining information for 196 cities and districts and usable quantitative data for 157 communities. Their arithmetic is stated plainly: \"In 1570, a total of 2,098,426 individuals lived in those 157 communities. Two years after the epidemic, by 1580, the population in the same places was reduced to 1,020,524. This represents 1,077,902 deaths, or a population loss of 51.36%.\" The instrument that makes this knowable is a tribute survey, not a public health system.",
      "sources": [
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.8
    },
    {
      "id": "c2",
      "text": "Set in the longer run, the same paper gives the figures that frame the century: \"In 1519, the year of the arrival of the Spaniards, the population in Mexico was estimated to be between 15 and 30 million inhabitants. Eighty-one years later, in 1600, only two million remained.\" The lower and upper bounds of that first number are a century-old scholarly quarrel in their own right, and the confidence here is set accordingly; the 1570-1580 comparison in c1 rests on administrative counts and is the firmer of the two.",
      "sources": [
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.6
    },
    {
      "id": "c3",
      "text": "The clinical description that modern work still starts from was made by a crown official on the spot. The Emerging Infectious Diseases paper attributes it to \"Francisco Hernandez, Proto-Medico of New Spain and former physician to King Philip II\", and reproduces what he recorded: \"high fever, severe headache, vertigo, black tongue, dark urine, dysentery, severe abdominal and thoracic pain, large nodules behind the ears that often invaded the neck and face, acute neurologic disorders, and profuse bleeding from the nose, eyes, and mouth with death frequently occurring in 3 to 4 days.\" This is a syndrome description with a case definition and a course, written in the middle of the outbreak by the man the crown had sent to survey the natural history of New Spain.",
      "sources": [
        "acuna-soto-2002-megadrought-megadeath"
      ],
      "confidence": 0.85
    },
    {
      "id": "c4",
      "text": "The fuller course, as the 2004 paper reconstructs it from the period accounts, was fast and haemorrhagic. \"The disease had a very short course, lasting three to five days. It started abruptly with high fever, vertigo, severe headache, insatiable thirst, red eyes and weak pulse. Patients became intensely jaundiced, very anxious, demented and restless.\" Hard painful nodules appeared behind one or both ears; chest and abdominal pain, dysentery and ulcers of lips and genitals followed; and then blood flowed \"from the ears, anus, vagina, mouth and nose.\"",
      "sources": [
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.85
    },
    {
      "id": "c5",
      "text": "Bodies were opened and what was found in them was written down. The 2004 paper states it in two sentences: \"Some autopsies were performed and the reports described a very enlarged and hard liver, lung hemorrhage and splenomegaly. Reportedly, none of the physicians that did those bare-hand autopsies acquired the disease.\" That is a post-mortem investigation of an epidemic conducted in the Americas in 1576, and its findings are organ findings, not humours. What the source does not supply is said here rather than filled in: it does not name who performed the autopsies, does not say who ordered them, does not say how many were done, and does not say whose bodies were opened or on what authority. In a colony where the dead of this epidemic were overwhelmingly indigenous, that last silence is not a small one.",
      "sources": [
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.8
    },
    {
      "id": "c6",
      "text": "The physical setting has since been reconstructed independently of the documents. Tree-ring records from Durango show that the 1545 and 1576 epidemics \"occurred during the 16th century megadrought, the most severe and sustained drought to impact north central Mexico in the past 600 years\", which the authors use to argue for a drought-driven concentration of rodent hosts amplifying transmission. The chronological coincidence is well evidenced; the causal mechanism built on it is the authors' hypothesis.",
      "sources": [
        "acuna-soto-2002-megadrought-megadeath"
      ],
      "confidence": 0.75
    },
    {
      "id": "c7",
      "text": "Neither paper claims to have identified the disease, and both say so in terms. In 2002: \"The disease described by Dr. Hernandez in 1576 is difficult to link to any specific etiologic agent or disease known today\", and \"the hypothesized viral agent responsible for cocoliztli remains to be identified.\" In the later paper: \"At the present time, cocoliztli cannot be definitely linked to any known disease.\" An entry that presented the indigenous-haemorrhagic-fever reading as settled would be misreporting its own sources.",
      "sources": [
        "acuna-soto-2002-megadrought-megadeath",
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.9
    },
    {
      "id": "c8",
      "text": "The competing explanation is bacterial and comes from ancient DNA, and it points back across the Atlantic rather than away from it. Work on a soldier buried at the 1652 siege of Barcelona recovered \"a large number of sequence reads mapping to Salmonella enterica Paratyphi C\" whose genome \"clusters with colonial Mexican strains\", and the authors read the Mexican material as showing that \"detection of Paratyphi C in association with victims of the Cocoliztli lends support to the hypothesis that S. enterica was a contributor to epidemics during recent historical times\". They are careful about how far this goes: \"more evidence based on genome-wide data from different locations and time periods is needed to assess its putative role as an epidemic pathogen.\" If the enteric-fever reading holds, cocoliztli belongs with the imported diseases of the conquest and not with the American ones, and the question is open enough that this entry states both readings and settles neither.",
      "sources": [
        "de-dios-2021-salmonella-barcelona-1652"
      ],
      "confidence": 0.75
    },
    {
      "id": "c9",
      "text": "What the record amounts to should be stated without inflation. A syndrome written down in the field by the crown's chief medical officer, organ findings from post-mortems, and two administrative population counts eight years apart are, together, the reason a sixteenth-century American epidemic can be argued about with data at all four and a half centuries later - every modern paper cited here is built on them. They did not save anyone. The medicine of 1576 had no treatment for what it was describing, the description did not slow the epidemic, and the population it was describing was collapsing under a régime whose arrival is inseparable from the epidemics that followed it. The contribution claimed here is the making and keeping of a usable record, and nothing beyond it.",
      "sources": [
        "acuna-soto-2002-megadrought-megadeath",
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.85
    },
    {
      "id": "c10",
      "text": "The limits of this entry's own evidence are worth naming. Everything above is read from three modern peer-reviewed papers, not from the sixteenth-century manuscripts they work from; no page of Hernández, of López de Hinojoso or of Farfán has been opened for this object, and those names appear in the 2004 paper's reference list and not in its body text. The evidence tier is set to secondary for that reason and not raised by the age of the underlying documents.",
      "sources": [
        "acuna-soto-2004-when-half-the-population-died"
      ],
      "confidence": 0.9
    }
  ],
  "takeaways": [],
  "faqs": [],
  "evidence_tier": "secondary",
  "evidence": {
    "level": "industry_observation",
    "source_types": [
      "paper"
    ]
  },
  "moat_flag": false,
  "winning_edge": "English-language accounts of cocoliztli split into two literatures that do not talk to each other: popular science about a mystery plague and a Salmonella genome, and colonial history about demographic collapse. What neither foregrounds is the thing both depend on - that there is a clinical description, a set of post-mortem findings and two censuses to argue from, made and kept by the colonial administration whose arrival is bound up with the catastrophe being counted. This entry puts the record and the death toll in one place, quotes the epidemiologists' own refusals to name the pathogen instead of resolving them, gives the ancient-DNA counter-reading equal standing with the haemorrhagic-fever one, and marks in the open what the sources do not say - who opened the bodies, on whose authority, and whose bodies they were.",
  "confidence": 0.8,
  "last_verified": "2026-08-11",
  "canonical_url": "https://hispanic-legacy.com/k/cocoliztli-epidemic-of-1576",
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  "jsonld": {
    "@context": "https://schema.org",
    "name": "The cocoliztli epidemic of 1576 and the record kept of it",
    "description": "The epidemic that halved what was left of the indigenous population of central Mexico in two years, and the paper trail it left. The crown's protomédico wrote down the clinical picture; bodies were opened and the organ findings written up; tribute counts were taken in 1570 and 1580 on either side of it. Modern epidemiology still works from those documents and still cannot say what the disease was. The record is the contribution; the thing recorded is the catastrophe.",
    "url": "https://hispanic-legacy.com/k/cocoliztli-epidemic-of-1576",
    "license": "https://spdx.org/licenses/CC-BY-4.0.html",
    "dateModified": "2026-08-11",
    "citation": [
      {
        "@type": "CreativeWork",
        "name": "Megadrought and Megadeath in 16th Century Mexico",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC2730237/"
      },
      {
        "@type": "CreativeWork",
        "name": "When half of the population died: the epidemic of hemorrhagic fevers of 1576 in Mexico",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7110390/"
      },
      {
        "@type": "CreativeWork",
        "name": "Salmonella enterica from a soldier from the 1652 siege of Barcelona (Spain) supports historical transatlantic epidemic contacts",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8430385/"
      }
    ],
    "@type": "Article",
    "headline": "The cocoliztli epidemic of 1576 and the record kept of it"
  }
}