You do know what doctor's said AIDS originated from, before it was politically incorrect to mention? Sex with monkeys.
And who told us not to practice beastiality? Of course from the atheist view point, I guess all of the animals are just one big family anyway.
I wouldn't know. I am not an atheist.
However, if all the human diseases were carried on the Ark, Noah and his family would have never survived.
According to your bible, it was Adam that checked out all the animal for their suitability as a "helpmate" ...