Ironically we don’t see much evidence of infectious disease in hunter gatherers. Now of course this only talks about those diseases we see evidence of in bones, but until we started keeping livestock and living in large close groups there doesn’t seem to have been much.

Obviously there still was disease. You’re never going to be able to find evidence of an infected wound or pneumonia in the skeletal remains, but the big killers like smallpox, measels, leprosy, etc. don’t develop until later.

Of course for those humans in environments that supported mosquitos malaria was still a huge problem.