History of Influenza:
Influenza probably first occurred after humans began domesticating animals and fowls, and transmitted from the animals to humans. However, given the similarity of its symptoms to other diseases like dengue, diphtheria, typhoid and pneumatic plague, it's tough for researchers to trace the exact history of influenza.
We find a description of flu symptoms in Hippocrates' writings more than 2400 years ago. The first recorded European Influenza epidemic happened in the 1580s. It is thought to have begun in Russia and then it spread fast to Continental Europe and Africa, wiping out populations on a massive scale.
There was another severe flu epidemic in 1743 in Europe. More severe epidemics followed in 1830-1833 and in 1918-1919. The latter, which started during the closing stages of the First World War, was dubbed the Spanish Flu and spread worldwide, killing an estimated 20 to 40 million people.
Flu epidemics in more modern times have been sporadic and less severe, in part due to better control and medical know-how. The notable ones were Asian Flu of 1957-1958, the Hong Kong Flu of 1968-1969, the Swine Flu in New Jersey in 1976, the worldwide Russian Flu in 1977 and the H5N1 avian influenza in Hong Kong and Asian countries in 1997. However, the emergence of new and hardier strains remains a matter of concern of public health programs around the world.