And yet, I've only ever heard the description of how European diseases effected the natives, and not the other way around. Even though- from what I've been told- the Europeans had worse hygiene and would rarely bathe, while native americans were cleaner and bathed often. what gives?
There is a popular theory in the medical community that Syphilis originated in the New World and was brought back to Europe by either the returning Columbian explorers or by the captive native American people that they brought with them.
This theory is supported by documents belonging to Fernandez de Oviedo and Ruy Diaz de Isla, two physicians with Spanish origins who were present at the moment when Christopher Columbus returned from America. The former, sent by King Ferdinand of Spain in the New World, confirms that the disease he had encountered for the first time in Europe was familiar at that time to the indigenous people who had already developed treatment methods.
Ruy Diaz de Isla acknowledges syphilis as an “unknown disease, so far not seen and never described”, that had onset in Barcelona in 1493 and originated in Española Island. Ruy Diaz de Isla is also the one that states in a manuscript that Pinzon de Palos, the pilot of Columbus, and also other members of the crew already suffered from syphilis on their return from the New World.
Opponents of the Colombian origination theory have attempted to disprove it through use of radio-carbon dating on skeletons with lesions unique to the disease. This has proven problematic in that no European skeletons with the lesions have been "reliably" dated before 1492. New World skeletons show the lesioning as far back as several thousand years.
Opponents of the theory point to 16 cases of skeletal lesions dated to the middle 1400s as evidence that syphilis was endemic to Europe prior to the return of Columbus. Those cases were revisited in 2011 and found that they all came from communities with significant seafood diets. This lead to the possibility of "old carbon" where older carbon from deep ocean upwelling is added to the community. This additional error brings the dating window inconclusive before 1492.
The first well documented outbreak of syphilis occured during the battle of Fornova in the war of Napolitano Succession, which occurred in July of 1495. It is also recorded that syphilis was at the time significantly more deadly. This would be consistent with new introduction of the pathogens to a group with no prior exposure to the disease, similar to the introduction of smallpox to the New World by Europeans.
In 2008 genetic sequencing of modern syphilis led researchers to tie the disease to an ancestral precursor disease "yaws" that is endemic to South America.
The genetic evidence, outbreak timing, and lack of historic contravening skeletal evidence before the 15th century means that Columbian exchange is the prevailing current understanding for European origin of syphilis.
So yes it does appear that there was exchange of diseases during the European conquest of the Americas, but smallpox being a respiratory droplet spread viral disease and syphilis being a sexually transmitted bacterial disease means that there was not parity with the virulence and spread of the exchanged diseases
Sources:
Origin and antiquity of syphilis revisited.
There is very good reason to suspect Native Americans did have their own set of disease that Europeans were not prepared for. I previously answered a similar question here, but will copy the relevant points.
The quick and dirty answer is that Europeans did often fall ill in the New World, and in many cases we assume these deaths were from diseases they encountered in the Americas. Contrary to popular opinion, the New World was not a disease-free paradise. About a year ago I wrote a post about evidence for epidemic diseases in the New World before contact. In that post I mentioned New World populations played host to a wide variety of intestinal parasites (roundworm, hookworm, whipworm, etc.), gastrointestinal diseases (Giardia, Entamoeba, and Cryptosporidium, etc.), Chagas disease, syphilis, Rocky Mountain Spotted Fever (and possibly Lyme), and tuberculosis. I also hypothesized they would be subject to occasional zoonotic events (when a non-human pathogen jumps into human hosts), just like modern populations with frequent access to wildlife/bushmeat trade. There is also reason to believe that observed epidemics that occurred after contact, like the cocoliztli (a Hanta Virus-like hemorrhagic fever) epidemics that swept through Mexico in the sixteenth century, were present, though perhaps more contained, before contact. Two cocoliztli epidemics, in 1545 and 1576, killed between 7 and 17 million people in highland Mexico, Europeans included. There is no evidence the pathogen responsible for the epidemic arrived from the Old World, but researchers suspect a massive drought altered the relationship between the murine host and humans, leading to increased chance of pathogen transmission, and a catastrophic epidemic. New research has muddied the cocolitzli argument, however, after the discovery of Salmonella enterica in contact period mass burials.
Next, when we read the accounts of early Spanish entradas in the U.S. Southeast, the authors make specific mention of crew members becoming ill weeks after their arrival in new lands. Nutritional and physiological stress from poorly planned colonization attempts likely decreased their immune defense, leaving them vulnerable to illness. Ayllón's 1526 attempt to establish a settlement on the Santee River in South Carolina ended in disaster. Of the original 600 colonists, all but 150 died from hunger and disease. Later, the 1528 Narváez entrada likewise suffered a series of unfortunate events in their attempts to find riches in Florida. 400 men landed in Tampa Bay, yet only four survived the trip to Florida. After a month of raiding Apalachee towns, members of the entrada began to fall ill. Cabeza de Vaca says
there were not horses enough to carry the sick, who went on increasing in numbers day by day... the people were unable to move forward, the greater part being ill.
Did members of Ayllón and Narváez's entrada perish from New World pathogens, or did they bring their own microbes with them, and perish as a result? We don't know for sure. The deaths began outside the incubation period for many common pathogens, giving us reason to suspect they did not bring those illnesses with them from Cuba, but rather encountered them from the neighboring maize-based agricultural populations like the Apalachee. Similar European mortality events are noted in Jamestown, where of the > 3,500 who arrived from 1617-1622, only 1,240 were alive in 1622. The chief cause of death was endemic illness, and the term "seasoning" was commonly used to describe the disease transition new immigrants needed to go through before their survival was more assured. We don't know for sure if the seasoning illnesses were infections brought from Europe, or if they included pathogens encountered for the first time in the New World.
To sum up, the popular assumption that Europeans did not encounter any new pathogens in the New World looks to be wrong. As we dive into the primary sources we find abundant evidence of infections, but it will always be a little difficult to determine, with 100% certainty, that those illnesses were from New World pathogens alone.
The idea that European (or Eurasian) diseases wiped out indigenous American populations after contact is actually something of a bit of a myth. Virgin soil epidemics did happen...in local, isolated cases. But the extremely high mortality rates from disease among indigenous Americans were facilitated and connected with displacement from war, malnutrition and enslavement. It's also not clear that many of the high-mortality epidemics that did hit native populations, such as the cocoliztli epidemics in 16th century Mexico, were actually introduced European/Eurasian diseases rather than indigenous ones.
For more, here is a link to the "Myths of Conquest: Death by Disease Alone" post by u/anthropology_nerd.
Most important immunological point to add to the discussion:
The American continent ( the new world) certainly have had their share of diseases. But there is a very important immunological aspect that many above answers have missed. It is due to the fact of diversity and semi globalization of the AfroEuroasian continent. Basically , the more diverse your community is , the more diseases will you likely encounter and be immunized. Also there is something called the monoculture/ multicultural genetic effect that basically means the more bio diverse a system is , the less number of diseases you shall face. Thus these two factors played to the advantage of the European conquistadors.
Europeans also encountered Yellow Fever and Malaria, two tropical diseases that killed untold numbers of Europeans in the greater Caribbean region. Outbreaks of such diseases affected newcomers to an area. Whereas a person with inherited immunity to Malaria, or in the case of Yellow Fever, childhood exposure, could soldier on quite well in such an environment, those contracting it as adults were going to have a rough go. When Yellow Fever hits a child, they typically suffer far less and survive with much greater odds than adults contracting it, who become dreadfully ill, and vomit a coffee ground looking substance before succumbing to the illness at high rates.
The vector for spreading these illnesses is mosquitos, and although the colonial Europeans did not realize this, they could not help but notice how new arrivals at lower elevations fared poorly during the rainy season and shortly after, when the outbreaks would occur. Those settlements at higher elevations did better, grew faster, and not surprisingly, that is where the majority of settlers went. In the comparatively cooler hills and mountains (say in Bogota) mosquitos were less present than in the swampy lower lying areas (Cartagena for example.). The ambient temperature was lower, so was the relative humidity, all making a mosquito less likely to seek a blood meal as the females are wont to do in hotter, more humid conditions. So settlements seemed to grow faster in areas where outbreaks were less frequent, less widespread, and less deadly.
Although the connection between outbreaks and mosquitos would not be firmly established until 1900 AD, the pattern of newcomers falling sick during rainy times was observed widely in the region. Quinine bark had long been used to treat Malaria, we have records of its use as early as 1632, and the Jesuits introduced it to Spain a few years later. A purified form was developed in 1820 to replace the bark as the primary treatment. But outbreaks had a devastating impact on new arrivals until the advent of modern mosquito remediation techniques.
I had often wondered why, as Spain sat humbly as a declining power in Europe, other ascendant empires such as the English, Dutch and French failed to take advantage, leaving all of South America to the Spanish and Portuguese. And it was not for lack of ambition, or lack of trying. The Dutch failed to seize Brazil in the 1620’s. The British themselves tried to seize Cartagena in 1741, Havana in 1762, and in both attempts were eaten alive by mosquitos bearing Yellow Fever and Malaria. The slim Portuguese and Spanish garrisons were able to wait out the rainy season behind elaborate fortifications, secure in their acquired immunity to Yellow Fever, and with Quinine bark for treating Malaria, and let illness decimate their foe without fortifications, immunity or treatment available.
Toussaint L'Ouverture knew his best hope of beating the French expeditionary force sent by Napoleon to end his rebellion on Haiti lay in waiting out the rainy season, when European newcomers to Haiti would feel the effects of these tropical diseases. Although he did not know the mosquito was his ally, he had seen the pattern in action with other groups of French arrivals. So hitting and running, disbursing and regrouping kept the French busy until the sickness came, and the prospects of the revolt’s success grew with each new infection.
Charleston, SC is still within the area of the Greater Caribbean region too, forming its northern border. The city of Charleston ‘enjoyed’ the reputation as a sick place amongst many European colonials. So frequent and intense were the outbreaks of Yellow Fever and Malaria, that the population voted with their feet and moved into the hill country of the interior in waves, where these occurrences were less prevalent. Had not been for that, Charleston, SC with its strategic location, beautiful surroundings and proximity to rich soils may have grown to be the equal of Philadelphia or even New York in terms of population and wealth. Outbreaks did occur in Philadelphia and New York as well, typically confined to summer, but did not last as long, occur as frequently or come on as deadly as those in Charleston, SC.
Mosquito Empires: Ecology and War in the Greater Caribbean, 1620–1914 By JR McNeil