Just the clap.
The Americas were lacking in large domesticable beasts.
According to Jared Diamond (Guns, Germs and Steel, 1997), since the europeans domesticated and lived with horses, pigs, sheep, chickens, geese, ducks, ox and cows they traded zoonotic diseases back and forth, and the survivors had genes to resist any number of diseases.
By the time settlers arrived in what would become America, something like 90% of the people here were already dead.
Dead of the diseases that to europeans were minor annoyances.
'If this is small pox, what must the great pox be like?' an Aztec is said to have wondered...
‘If this is small pox, what must the great pox be like?’ an Aztec is said to have wondered...
https://en.wikipedia.org/wiki/Syphilis#Etymology
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