It’s been more than 90 years, but human beings may have introduced what is now known as the swine flu virus to pigs during the Spanish flu pandemic in 1918, claims a May issue of The Journal of Virology. The Indian Express looks back at what was one of the worst pandemics the world has ever known and which, lament some experts, has become the forgotten flu because the lessons that could have been learnt from it were often overlooked:

What was the Spanish flu?

The Spanish flu, also known as La Grippe, was a pandemic that struck the world in 1918-19 and affected the US, Europe, Asia, Africa and parts of South America, by some accounts infecting a fifth of the world. The passage of the disease was greatly aided by the travel made necessary by World War-I. Despite its name, the Spanish flu is widely acknowledged as first rearing its head as an epidemic in America, although there is speculation it may have originated in China. It is believed that the pandemic earned its monicker due to the high number of mortalities in Spain, as well as the fact that most reliable news of its spread came from the country, which had less censorship due to its neutral status during the war.

How did it spread?

The flu hit the world in three waves, the second being far deadlier than the first and third. In the first wave, which began around March 1918, the flu seemed relatively harmless and affected the elderly and already ailing rather than the young and healthy. About five months later, the trend changed, as the virus had apparently mutated and become more deadly — the war may have had a part to play in this, as instead of staying home, sick soldiers continued to fight in trenches and go to overcrowded hospitals. This also considerably lowered the age of fatalities as the soldiers and their acquaintances were most likely young adults.

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