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Comment by todd8 | Hacker News Reader

Although some posts suggest that the USA may experience malaria at some point in the future because of global warming; in actuality, the USA has already experienced malaria.

In 1882, the range of malaria in the USA extended from the Canadian border on the north to southern border with Mexico on the south. The only states of the current 48 contiguous states unaffected were Nevada, Utah, Arizona, Idaho, Main, Vermont, and New Hampshire. Something like 41 states had malaria cases (the maps are a bit hard to read).

Approximately 375 cases acquired in the USA per 100,0000 population were reported in 1920.

Eradication efforts continued until the 1950s when the USA essentially became free of malaria. See [1].

[1] https://www.cdc.gov/malaria/about/history/elimination_us.htm...

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The eradication efforts in the US included lots and lots of DDT.

The Little House on the Prairie family caught malaria, and was so sick they almost died of dehydration because they couldn’t get down to the river to drink.

https://littlehouseontheprairie.com/dr-george-a-tann-pioneer...

This is something that has confused me for a long time. America definitely has mosquitoes (I’m from Washington, DC). How are there mosquitoes but no malaria?

It's only a few (4?) species of mosquito that carry malaria, out of hundreds of species in total.

It's bizarrely hard to find good explanations of this! The National Malaria Eradication Program, between 1947 and 1951, cut down on malaria transmission enough that the parasite was driven locally extinct. They drained wetlands where mosquitoes bred, sprayed house interiors and mosquito-heavy areas with DDT on a very large scale, and generally engineered a very specific ecological disaster, depriving the parasite of the human hosts needed for part of their reproductive lifecycle. Without enough infected humans, the parasites died out.

Crucially, they didn't need to get rid of all the mosquitoes to do this: they just needed to drive mosquito-to-human transmission low enough for long enough.

https://en.wikipedia.org/wiki/National_Malaria_Eradication_P...

If this were the complete story then just a single person coming back to the USA infected would lead to mass infection...

Clearly that hasn't happened.

Malaria does not spread from human to human, you need infected mosquitos in the mix. So you would need to get a breeding population of infected mosquitos biting humans for it to start spreading.

Only explanation I can think of is that the malaria from elsewhere is different somehow, worse adapted to US conditions.

We do still have mosquito abatement programs too.

I know here in Louisiana the local abatement program has trucks that spray synthetic pyrethroid chemicals (resmethrin, sumithrin and prallethrin) at night and uses an organophosphate (naled) from planes.

And residents are routinely urged to be aware of and eliminate standing water on their property.

We just don't use DDT anymore -- we almost wiped out our state bird with it.

Edit: I have to wonder how much housing changes also mattered. With modern air conditioning and well sealed homes it's fairly rare to have mosquitoes in the home at night.

The answer is malaria eradication efforts never stopped neither in US nor in Europe. It's just as routine as renewing asphalt roads or maintaining sewers

The Anopheles mosquitos [1] which spread human malaria are present at some level across about half of the US, but are just not especially abundant here compared to other mosquitos that do not spread malaria.

In fact, of the ~200 mosquito species which occur in the United States, only 12 are known spread any sort of human disease [2].

[1] https://en.wikipedia.org/wiki/Anopheles

[2] https://www.cdc.gov/mosquitoes/about/mosquitoes-in-the-us.ht...

There's a reason the CDC is in Atlanta.

Yea but I’m an Atlanta native and never hear of malaria. Plenty of mosquitos around here.

That's because they did their job well.

https://upload.wikimedia.org/wikipedia/commons/b/b3/MalariaM...

I grew up in Alabama, and remember a few times a summer seeing the "mosquito truck" drive by, spraying pesticide as I played in the yard. I guess it works!

I don't think we do it for malaria these days, just to reduce mosquito stings? Thinking about like mosquito sprays in Chicago...

AFAIK it's more about West Nile and EEE, maybe Zika and even others.

Though, incidentally, if you reduce/eliminate mosquitos carrying West Nile, Zika, etc ... you also reduce/eliminate the ones carrying Malaria :)

We had those growing up in suburban Chicago too -- in my case in the 70s. The trucks would only appear at dusk. We dumb kids thought the fog was a hoot so we would jump on our bikes and chase behind the truck hooting at the novelty, breathing in who knows what chemicals. I can still remember the smell.

> breathing in who knows what chemicals

Probably DDT. Not thwebest of ideas!

In the 1970s? No, almost all use of DDT in the US ended in 1972.

I seem to recall this in the Midwest as recently as the 90s

My dad told me similar stories from midcentury New York.

It was probably malathion, which is an organophosphate pesticide that is considered low toxicity, although it may be a carcinogen.

In FL, we still have the mosquito truck end up coming by at least every other week.

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