Re: "I do live in a subtropical climate. No malaria yet" Malaria is not confined to hot climates. It was so prevalent in ancient Rome that it was called "The Roman Fever". It was prevalent in London (Latitude 51.5 North ! ) until the mid-19th century. It was not eradicated from the USA until the early 20th century. Australia was not declared malaria-free until 1981.

There were even malaria outbreaks north of the Arctic Circle in places including Russia and Finland.

( https://uk.news.yahoo.com/thinking-malaria-tropical-disease-huge-145400564.html )