Building on earlier posts, the Europeans were exposed to a lot germs, diseases, etc., due to the fact that the naturally occurring flora and fauna of Europe were very diverse. In addition, the population density, Europe-wide, was intense, so people were naturally exposed to many diseases. Think of the devestation of the Black Death…
In contrast, Americans were not: less population density to spread disease and acquire an immunity, less diversity of flora and fauna. Thus, their immune systems were much more susceptible to smallpox, which wiped out upwards of 95% of their population.
Europeans were susceptible to syphilis, as someone posted, and also yellow fever and malaria. But the impact of those diseases on Europeans didn’t reach anywhere the scale of smallpox to the Americans.
I agree in part, disagree in part. Possibly I might even remain topical.
Likely populations in Europe generally were more dense than in the Americas in 1492, but there were still very heavily populated areas, like the Valley of Mexico and the Mississippi Valley that would have rivaled in population any particular location in Europe.
I don’t know how flora could affect human disease. But fauna sure can, because humans and animals often trade diseases, or variants thereof. I have read, for example, that Indo-Europeans are particularly resistant to cattle vector diseases, of which smallpox is a variant or mutation. They spent millenia as herders on the Eurasian steppes before invading Europe and India, and brought cattle (and other herd animals) with them when they did. Supposedly that’s also why Indo-Europeans, pretty much alone among the world’s peoples, retain lactose tolerance into adulthood. If your livelihood is cattle for thousands of years, it is a survival advantage both to resist cattle vector diseases and to be lactose tolerant long-term. Wherever Indo-Europeans went, traveled or traded, they shared their diseases. Consequently, people in the Arab or Oriental lands (and to a degree in Africa) also gained tolerance to certain diseases.
Hogs are also vectors for human diseases, influenza famously being one of them. There were no hogs in most of North America before DeSoto brought them there. (Javelinas in the extreme southwest notwithstanding) Indians were also devastated by hog vector diseases like the flu. Nobody really knows what diseases killed the massive Mississippi Valley populations between DeSoto and Marquette, but it is believed by some that hog vector diseases did it.
Interestingly, sickle cell disease is a malevolent variant of a blood cell trait that confers relative resistance to malaria. Supposedly that’s why blacks are both relatively resistant to malaria and uniquely subject to sickle cell disease. The resistance to malaria was known to the early slavers, which is one of the big reasons why African slaves were brought to some of the more malarial parts of the New World.
Interestingly, “malaria” is a word of Italian origin. It has, at times, been very prevalent in sub-Alpine Italy. Long ago, rice planters in the Arkansas River Valley brought families of Italians over to work the rice fields because they were believed, perhaps rightly, to be relatively resistant to malaria. Not being slaves, they soon decided to leave, and many settled in the more congenial hills of NW Arkansas where a number still live in and around a town named “Tontitown” (after Revolutionary War figure DiTonti). It’s on the outskirts of the Springdale/Fayetteville/Bentonville/Rogers complex, and has some of the best Italian restaurants anyone ever saw. If you haven’t eaten at Mary Maestri’s, for example, you haven’t lived.
Possibly Rich Olezewski knows that story better than I do.