What happens if an immunodeficiency virus makes the species jump from chimpanzees to humans earlier than IOTL and manages to spread throughout the world? IMO, the perhaps *most interesting* time to see it happen would be during the 1600s Atlantic Slave Trade, where a captured African carrying the disease is brought, along with the virus, to the Americas (preferably North America, where they will survive long enough for the disease to spread) and from there into the broader developing world trade networks? I also find it possible for the disease to spread on a slave ship, possibly by sexual contact if the victim is female and is assaulted by a crewman, otherwise via exposure between salt sores of the sort that seem likely to develop in the conditions of a slave ship. How fast does the disease spread? How does this impact the course of the 1600s, which already faced massive upheaval OTL in the form of the 30YW, Ming Collapse, etc? Afterwards?