The "Spanish flu" didn't come from Spain.
The 1918 to 1920 pandemic killed an estimated 17 to 50 million people. It got its name because Spain was neutral in the First World War and its press could report freely, while belligerent countries censored the news. Spain therefore looked like the epicentre. The first documented cases were in Kansas, USA, in March 1918.
Useful: Where something is reported first is often just the place with the freest press.
Source: en.wikipedia.org