TLDR: Global HIV/AIDS epidemic ignited by slavery in the 1920s Belgian Congo.
The ignition of the global HIV/AIDS epidemic has been traced back to 1920s Léopoldville, now known as Kinshasa. Combining the work of scientists with what we know about the history of the Belgian Congo in the 1920s, we can conclude that slavery, perpetrated by certain Belgians and other Europeans who held power in the Belgian Congo during that time period, caused the HIV/AIDS epidemic. Although King Leopold II was technically dead by the 1920s, he did begin the Belgian colonization of the Congo, and the slave labour regime perpetrated during said colonization, so basically, HIV/AIDS should be renamed to "King Leopold's Ghost".
You can read a more detailed explanation here:
https://www.reddit.com/r/AntiSlaveryMemes/comments/120tdph/king_leopolds_ghost_continues_killing_to_this/