I honestly don't have much planned in the way of plagues going from the New World to the Old.@JSilvy nice to see you making another Native American timeline. Adding to @traveller76, have to ask will there be any New World diseases that will be introduced to the Old World? I’m curious because the spainish conquered some of the more populated cities that happened to be near mosquito infested wetlands, America has more animal domesticates ITTL, and there are and will be lot of spainish interactions with natives.
Regarding the nature of mosquito-infested swamplands and the issue of malaria spreading in the Americas, I do plan to discuss that more when I dive deeper into the slave trade.