Did the US pay reparations to essentially all the nations for the 1918 flu? This originated among cattle in Kansas, and killed 50 million people: more than WW1 and WW2 combined.
The above claim that it started in Kansas is one hypothesis among many others. This is another hypothesis from the same wikipedia section: "In 1993, Claude Hannoun, the leading expert on the 1918 flu for the Pasteur Institute, asserted the former virus was likely to have come from China."