In my story, I have two late renaissance era cultures discovering each other for the first time and I plan for the story to develop into more of how they both understand each other. However, I don't want it to be a battle against disease spread so I need a reason for why there wouldn't be any transmitted disease like in how we brought disease to the New World.
I thought that the flu and other diseases could have developed in both cultures separately since they both have big cities with poor hygiene that would have been a hotbed for disease. Could such an explanation work?
an important fact I forgot to mention is that the two civilizations are two different species but they are descendants of the same animal.