I had a little bird,
Its name was Enza,
Opened up the door
And In-Flew-Enza.
—Children's jump-rope rhyme, 1918

In fall, 1918, an outbreak of epidemic influenza spread across the entire world. Erroneously dubbed "the Spanish Flu," the pandemic was to eventually cause the death of 40-50 million people, more than the total casualties of the first World War.

The first "wave" of flu began in spring, 1918, and was similar to the seasonal flus that were usual for that time of year. Although difficult to determine, it is believed that the Spanish Flu originated in Haskell County, Kansas, in February of 1918. From there it spread to Camp Funston, in Fort Riley, Kansas, and then was transferred overseas to Brest, France with American troops bound for the battlefields of Europe, becoming more virulent with each generation of influenza virus. By Fall 1918, there was scarcely a place on earth that the virus had not reached, leaving a toll of debilitating illness and death in its wake.

By the end of the outbreak in Spring 1919, nearly every inhabited location on the planet had been affected by the Spanish Influenza. It is estimated that between 25-30% of the world’s population contracted the Spanish Flu. As with many epidemics, the poorest countries and continents fared the worst: Asia and Africa are estimated to have lost approximately 5% of their population; overall, worldwide the death toll is considered to be between 3-5% of the human population.