Spanish flu is a type of influenza that emerged after World War I, is apparently the same disease with avian flu today. It arrived in many countries along with the return of soldiers, mainly affecting young and having a high mortality rate which killed between 50 and 100 million people worldwide, between 1918 and 1919. It is believed that it was one of the most lethal pandemic in human history. Many of the victims were young and healthy people, totally different from the other pandemics that affected children, the elderly and people with weakened health.
The disease was first noted in Fort Riley, Kansas, United States of America on March 11, 1918. Allies of World War I called it Spanish Flu because the flu received more attention in Spanish newspapers than in the rest of Europe. Spain was not involved in the conflict and the press was not censored like in the rest of Europe.
Pandemic mortality rate is unknown but is estimated between 2,5-5% of Earth population of the time and that 20% have suffered illness. Flu killed 25 million in the first 25 weeks .
Spanish Flu spread in 1918. It was an influenza pandemic that spread to nearly every part of the world. It may have been caused by an unusually virulent and deadly influenza A virus strain of subtype H1N1. The pandemic lasted from approximately March 1918 to June 1920, spreading even to the Arctic and remote Pacific islands.
It is estimated that anywhere from 50 to 100 million people were killed worldwide which is from three to seven times the causalities of the First World War (15 million), making it the most deadly natural disaster in human history. Although the first cases of the disease were registered in the continental U.S, and the rest of Europe long before getting to Spain, the 1918 pandemic received its nickname "Spanish flu" because Spain, a neutral country in WWI, had no special censorship of news regarding the disease and its consequences.