Answer:
Influenza, in the year 1918
Explanation: The Influenza pandemic 1918, was one of the severe pandemics in the world history. It had a bigger death toll than world war I. About 33% of the world's population was infected and it mostly affected the people aged between 20 to 40. Spain was the first to report the pandemic as it had free press.
It led to a great stride in genetics as scientists had to find the cause as well as cure to an unknown disease.
