The MesoAmerican Black Death: Huey Cocoliztli

The conventional narrative about epidemics of infectious diseases in indigenous Amerindian after the Colombian exchange goes something like this- Europeans and their African slaves introduced infectious diseases, such as Smallpox, which decimated the Amerindian population. While this narrative is fairly accurate, it ignores the devastation caused by epidemics of infectious diseases that were indigenous to the Americas. Contrary to popular belief, such infections caused as much death as the introduced infectious diseases- especially in Mesoameria.

I am guessing that most of you have never heard about something called Huey Cocoliztli. Google it here: Huey Cocoliztli. Apparently it was an epidemic infectious disease that killed millions of Mexicans decades after a significant number of them died of imported diseases such as Smallpox. It stands out from other epidemics of infectious diseases that swept the region we now know as Mexico on three points: (i) It killed more people than Smallpox; (ii) The course and symptoms of the disease were unlike anything the Spanish had ever seen; (iii) The indigenous people had legends of massive sudden deaths associated with a certain set of climatic conditions. A good introduction to the topic can be found here- Was the huey cocoliztli a haemorrhagic fever?

Many scientists used to think that Huey Cocoliztli was an old world disease such as epidemic Typhus, Yellow Fever or atypical forms of Smallpox. However the symptoms described by Spanish physicians who were familiar with these diseases tell a different story.

The fevers were contagious, gripping and continuous, very much a total pestilence and in great part lethal. The tongue, dry and black. Intense thirst, urine the colour sea green, leafy green, and black, and from time to time changing from a greenish to a pale colour. Pulse frequent and rapid, but small and feeble, sometimes almost none. The eyes and all of the body yellow. Following (these symptoms) delirium and convulsions. (There appeared) pustules behind one or both ears, and hard and painful tumours, pain in the heart, chest and stomach, trembling and great anxiety and dysentery; the blood, which flowed from a cut vein was the colour green or very pallid, dry and without any serosity. In some gangrenes and lesions erupted on the lips, the pudenda and other areas of the body with members putrefied, and blood flowed from their ears; in truth, in many people blood flowed from the nose.

If you read the entire description and other contemporary descriptions, it seems that Huey Cocoliztli presented as an acute fever with a minimal and localized rash whose main symptoms and effects on the body are centered around its effects on blood coagulation such as nosebleeds (epistaxis), conjunctival suffusion(blood-shot eyes), vomiting of blood (haematemesis), bloody stool- (dysentery), frank blood per stool (haematochezia), haematuria (blood in the urine), bleeding from the gums (gingival haemorrhage), and vaginal haemorrhage. The effects on urine color are also highly suggestive of intravascular haemolysis. Furthermore the incidence of the disease was linked to the extent of your physical involvement in agriculture, so that mexican peasants who worked the fields had the highest incidence of that disease while those who lived and worked away from fields rarely suffered from it. An other interesting feature of this disease was that it killed the young while barely affecting old people, who also survived the disease in far higher percentages than their adult children and grandchildren.

Indeed, the lasting socio-economic effects of Huey Cocoliztli on Mesoamerica were linked to the fact that it killed a majority of the young Mexican peasants and laborers during it many major and minor outbreaks from 1545-1580 AD.

There are however two types of questions about this disease that have never been properly answered-

1. What is the identity of the microorganism (likely a virus) responsible for this disease? If this disease was transmitted by animals (very likely), which species of animals are the natural reservoir of this virus? and does this virus still exist? Why did it disappear as an epidemic disease about a hundred years after its dramatic appearance in the mid 1500s. Why were the later epidemics smaller, even though the disease remained fairly lethal in those who suffered from it.

2. While epidemics with similar symptoms were known before the arrival of the spanish, why did their arrival make things so much worse? Was it linked to habitat disruption whereby the Spanish forced the local population to expand agriculture in geographical locations containing the animal carrying the virus? What was the role of climatic changes especially recurring droughts in those decades on humans and the animal species carrying the virus?

What do you think? Comments?