Malaria is not inherently a tropical region disease. It routinely plagued Europe until the 1950s. Russia for one example had a huge Malaria outbreak in the early 1920s as did Eastern Europe broadly.

"Gustavo Pittaluga (1876-1956) estimated that in 1923, 18 million people suffered from malaria in Russia, and that sixty thousand deaths occurred out of a total population of about 110 million (Anigstein, Pittaluga, 1925). Similar observations were made throughout the whole of eastern and south-eastern Europe and the former Ottoman Empire."

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104...

Europe and the U.S. used to have Malaria. The name -- bad air -- is Latin, the Romans thought it originated from bad swamp air. Shakespeare mentioned it time and time again in his plays.

I'm pretty sure what Shakespeare was referencing is a much more general idea prevalent in his day - that smells (not necessarily unpleasant ones) could be poisonous, and could be warded off by opposing "good" smells. This roughly coincided with an explosion of scented-good manufacturing as a cottage industry, although I'm not sure which way the arrow of causation ran there.

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2) Limiting chance of mosquitoes biting people (aircon)

3) Limiting the population with malaria (the fewer people with malaria, the less chance of a given mosquito biting someone with malaria and thus becoming a carrier)

...which actually isn't that far-fetched for a pre-medical society to conclude, given that mosquitoes breed in warm, still waters.

No. The name is Italian. It predates Italian colonies in the tropics. It's a disease which was endemic in marshlands believed to be caused by bad air Mal aria and was in Scotland amongst other places.

Malaria is not exclusively tropical. Nor is dengue or mosquito borne encephalitis. Tropical wet regions sustain mosquitos. So do cooler climates.

I agree that covid-19 seems to have a larger potential breadth, and didn't intend to downplay its significance.