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How Malaria Was Eradicated In The U.S.

This episode of Real Science is brought
to you by CuriosityStream. Sign up today at and get free access to Most of us probably think of malaria as
a disease confined to the tropics. It thrives in Southeast Asia, the eastern
Mediterranean, parts of Central and South America, and Africa which carries most of
the global malaria burden. And when we think of malaria we probably think of
humid jungles or tropical lakes in equatorial regions. As of 2017, 87
countries had ongoing malaria transmission, with places like the US and
Europe appearing to be safely off the list. It’s easy to assume that’s because
the US and Europe are not tropical places. But in fact, both places used to
be riddled with malaria. In the U.S. in particular, it debilitated towns, caused
thousands of deaths, and even determined the settlement patterns of the country.
But now it has been so thoroughly erased that many people don’t even know it used
to exist there at all. So how is it that malaria once thrived in the US, and why
did it disappear? And perhaps most importantly, can the methods of its
elimination in the US be copied elsewhere? To understand the spread of
malaria in the US it’s important to consider the life cycle and behavior of
the Plasmodium parasite and it’s vector, the mosquito. Malarial parasites are
carried by the Anopheles mosquito which breeds in still water such as marshy
ponds and swamps, features that exist in great numbers in the eastern and
southern United States. When a mosquito bites an infected person a small amount
of blood is taken in which contains microscopic malaria parasites, which then
mate in the gut of the mosquito and begin a cycle of growth and multiplication.
About one week later, a form of the parasite called a sporozoite
migrates to the mosquitos salivary glands. When the mosquito takes its next
blood meal these parasites mix with the mosquitos saliva and are injected into
the next person being bitten. The sporozoites then rides in the
bloodstream towards the human liver. Once it arrives, it enters a liver cell. There
it undergoes many rounds of division and multiplication. A single infected liver
cell can lead to the creation of thousands of new parasites. These new
parasites then migrate to infect red blood cells where they can hide from the
body’s immune system. Here they consume the contents of the red blood cell and
divide to create even more parasites. Eventually the red blood cell they are
inhabiting ruptures and the new parasites called merozoite are released.
These continue the cycle by invading other red blood cells which subsequently
also rupture. The parasites living in the bloodstream is what causes the symptoms
of malaria, which can range from headaches, to fever, to seizures, to death
if the parasites block arteries in the brain and kidneys. At this point the
parasite within the human bloodstream can then be ingested once again by a
mosquito and transmitted to another unsuspecting human and the cycle begins
again. No one knows for sure when malaria was first introduced into humans but it
is thought to have been in prehistoric times. But as for the US its
infestation with the disease was not brought about until the 17th century
with the first arrival of slave ships from Africa. Once the parasite was
introduced to North American shores places like the wet low-lying plains of
Virginia and South Carolina became overrun with the disease. The Carolinas
were initially thought of as a land of paradise by European settlers but with
the introduction of malaria became known as a ghastly place to live. An English
proverb at the time said “those who want to die quickly, go to Carolina”.
Incoming immigrants thus labeled certain colonies as healthy and others as
dangerous. The Caribbean was understood to be the most dangerous, with Florida
and the Carolinas being a close second. The Chesapeake was a bit better but only
in the northern colonies – New York, New England, and Pennsylvania, did European
settlers thrive. And because most African slaves had some tolerance to malaria and
white indentured laborers from Europe did not, demand for slave labor in
malarious areas also increased. Malaria, along with other diseases like yellow
fever, thus had a substantial role in determining settlement and labor
patterns in the colonies – patterns that would eventually lead to the Civil War.
Malaria wreaked havoc in America for centuries, and by the time of the first world
war, malaria was a huge problem, especially
for the military, where men training in the south were picking up the disease in
rapid numbers. 10,500 admissions for malaria were reported from April 1917
through December 1919, involving a loss of 130,000 training days. By the 1930s malaria had become concentrated in 13 of the
country’s southeastern states and there were well over a million cases during
the Great Depression. Malaria had become a major national problem. By 1933, malaria
deaths in America reached a new peak. Malaria thrives when poverty is high
where people lack access to adequate health care and nutrition, and America
had just descended into the Great Depression. But for the next decade where
malaria should have boomed, it instead retreated. But the exact reason why isn’t
as clear as you might think. To this day scientists and historians fiercely argue
about which of the many factors was the key to its eradication. At the time there
were two camps of opinion on the best way to get rid of malaria. The first, to
attack the parasite inside the human body. The second, to eliminate the vector
for the disease, the mosquito. If it were possible to treat all members of a
community at once and eradicate the parasite within them, then malaria could
be wiped out, even if the adult mosquitoes carry on biting everyone. For
hundreds of years people were aware that quinine obtained
from cinchona bark could be used to alleviate the symptoms of and even
prevent malaria. So in 1916 scientists carried out a study on 500,000 people in
Bolivar County Mississippi, a place plagued with malaria, to see if
quinine could be used as an effective treatment. They gave out doses of quinine
for free and indeed found that it reduced malaria infections by 90%.
However even though high doses of quinine were good for quickly ending an
episode of fever and chills they found that people would not take enough
quinine on a regular basis to prevent infection long term because of its bad
side effects. Therefore, it was useful for interrupting
and infection and relieving symptoms but more often than not the infection would
just come right back. Thus quinine distributed in large numbers definitely
helped but it would not be the complete answer to getting rid of malaria in
America. It would take more than medicating the population to get rid of
this persistent disease. Once it became known that the mosquito was the cause of
malaria many people believed its death would be the way to eliminate the
disease. But killing the adult stage of the mosquito is challenging since they
infest the world in 3d space and at the time there wasn’t any reliable methods
for doing so. Therefore many believed it was best to attack the mosquito at the
most vulnerable point in its lifecycle – the larval stage. Mosquitoes lay their
eggs in marshy stagnant water which then hatch into larvae which will eventually
develop into full-grown malaria spreading mosquitoes. And so one way to
hit them where it hurts is to eliminate their breeding grounds, the marshy
stagnant water. And unluckily for the mosquitoes the 1930s brought a wave of
public works projects intended to boost the economy, including malaria control and
lots and lots of digging. The Works Progress Administration put people to
work digging 32,000 miles of ditches and draining 623,000 watered acres. And when
draining wasn’t possible, coating the surfaces of ponds with oil and spraying
their habitats with a compound called Paris green further smothered the larvae.
These efforts coincided with a sharp decline in malaria transmission in the
1930s, but by 1940 while less common than it once was,
malaria still persisted. During this time the US army still
trained its men in many areas of the Southeast US where malaria still had its
grip. Not wanting to repeat the hard lessons from the First World War,
large-scale anti malaria operations were undertaken. 40,000 acres of surface water
was eliminated 4.7 million gallons of diesel oil larvacide was used, and 9.8
million dollars was spent on this all-out war against malaria. Then in 1944
one of the most effective mosquito killers of all time was invented – DDT.
Thanks in part to DDT by 1945 malaria transmission in the US had dropped
significantly and the disease’s days in the US were numbered.
Then in 1946, the CDC was born, with the primary mission of finally getting rid
of malaria in America once and for all. During the CDC’s first few years more
than 6.5 million homes were sprayed with DDT. This along with even more wetland
drainage pushed the disease out of existence. By 1951 malaria was considered
eliminated altogether from the country. The onslaught of DDT, drainage works,
habitat oiling, and preventive medication had finally worked. However there are
dozens of other factors which also contributed to malaria’s death in
America. Some historians firmly believe that the key factor in its eradication
was actually population movement away from rural areas, while others think it
was simply better education about the disease that did the trick. Others think
it was general economic improvement and the installation of screens on houses,
and yet others think it was actually a massive drought that led to malaria’s
demise. This multivariable attack on the disease and the uncertainty that that
causes has left scientists unsure of how to best translate these results to other
parts of the world today. This, along with the fact that many of the approaches
taken in America cannot or should not be taken in other parts of the world has
made eliminating malaria globally a massive, still unsolved problem. Most can
agree that draining marshy areas in America helped lead to malaria’s decline
in some amount. However, in Africa where most of the world’s cases of malaria
occur today, such methods are not feasible, because the mosquitoes there
breed in small pools of water that form from rainfall, spread across the
landscape. It is difficult if not impossible to predict when and where the
breeding sites will form and to find and treat them before the adult mosquitoes
emerge. DDT too was instrumental in eliminating
malaria in America since it’s so effective at killing mosquitoes. The
problem is we now know it’s also great at killing everything else. It was banned
pretty much everywhere in the world in the 1970s and 80s, and although it’s
still being used in some places scientists urged it to be used as a last
resort to combat malaria. Distributing anti malaria medicine also would
certainly help if everyone vulnerable to the disease had plentiful access to it
but the cost of this can be prohibitive and while some progress can be made with
this method the geography of places like Africa make it so even if you make gains
in one area, the disease will just pop back up again as it returns from a
surrounding area. These problems along with new drug and insecticide resistance
within the parasite and mosquito makes it so new approaches must be taken in
this global battle. Luckily organizations like the Bill and
Melinda Gates Foundation are working towards just that putting their
resources in large part towards better data collection along with research and
development for creating new medicines and vaccines. And recently scientists
have been experimenting with genetically modified mosquitoes intended to
drastically reduce mosquito populations in the wild. It’s a drastic new
development in the battle against mosquito-borne illness and is something
we’ll cover in depth in a future video. No single strategy to combat malaria
will ever be effective everywhere and unfortunately there’s no silver bullet
for this centuries-old problem. But with long term commitment and a flexible
strategy along with much more funding it may be possible to eliminate malaria
everywhere in the world one day soon.
Malaria was in part wiped out in America because of effective military strategy – a
strategy that took thousands of man-hours and millions of dollars and at
the time seemed impossible. There have been many unlikely achievements like
this throughout history, from malaria and yellow fever eradication in different
parts of the world, to the building of the Panama Canal, to the successful
invasion of Normandy on D-Day, all things which took unprecedented levels of
coordination and strategy, and all things that easily could have failed with the
wrong plans set in motion. You can learn more about the detailed logistics for
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don’t know is a collaborative series where different YouTube creators break
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53 thoughts on “How Malaria Was Eradicated In The U.S.

  1. @Real Science aka Brian McManus, can you please make a video on how do you make so high quality videos with high production value. I do really want to learn this style for my software development YouTube channel.

  2. I remember reading that most human deaths were caused by Malaria. I'm talking since our early cave dwelling days.

    Also that parasite is not a bacteria or a virus it's a much more complicated unicellular Eukaryotes, they aren't Amoebas or fungi or plants. Most dangerously is that if a vaccine or medicine is found it can quickly evolve an immunity to it because there are millions of it being born all the time and since they aren't asexual there is a much greater chance for random mutations that will eventually yield an immunity.

    This disease has haunted all of us since our earliest days.

  3. I'm an American, I like to think I'm well informed on a lot of topics, and I'm always trying to learn more, but I had no idea that America had ever had a malaria problem. Thank you for making this video, and for teaching me more about the world we all live in.

  4. The CDC wasn't born as the Center for Disease Control as we know it. Before that, it was the Contagious Disease Center, and before that it was the Office of Malaria Control in War Areas, a subset of the DoD. We can thank the CEO of Coca-Cola for the CDC's current incarnation, as he donated the buildings and land to the burgeoning CDC to eradicate malaria.

    Here's hoping we can elimenate Malaria around the world in the future.


  6. Sickle cell anemia make you immune to this
    In germany we hd this decades ago

    then we forced the Rhine river into a straigh and killing off its sprawling sidearm
    thus drying out the swamps

  7. I kinda want to check this nebula thing out, but on the other hand I already have curiositystream subscription, so I would miss out on the deal. Feelsbadman

  8. So far the videos have been focused on biology type stuff, which I have enjoyed. But will there be any videos on astronomy or astrophysics?

  9. So far the videos have been focused on biology type stuff, which I have enjoyed. But will there be any videos on astronomy or astrophysics?

  10. It's thanks to a massive faker called Rachel Carson why Malaria wasn't wiped out completely. The US stopped supporting DDT spraying globally (while DDT was still effective) because she fooled the public. She faked her statistics and knowingly lied in a book called Silent Spring. She claimed the number of Robins had been falling while the Audubon society's data showed record numbers of Robins. That this fraud is acknowledged as the Mother of the Environmental movement is representative of the type of science environmentalists accept (esp. groups like Greenpeace). In a case of Karmic justice, Rachel Carson died of cancer. But she's responsible for more deaths than Hitler or Stalin.

  11. Some folks in California figured out how to genetically engineer mosquitoes to make the entire population infertile, they tested it and it took the population down by like 96%. I think we might have found that silver bullet after all

  12. Great video as usual, I didn't know we had no idea we had such a horrible Malaria problem in the past. Thankfully it's eradicated though, because I currently live in Florida. Also, that deal for Nebula and curiosity stream is actually a great deal, so I'm signing up as we speak. I'm sure I won't be disappointed, there's a lot of good channels on there.

  13. You should talk about the research being done on CRISPR sterilization programs of anophales and Aedes species of mosquito (2 of these most problematic genus of mosquitoes) they plan on being able to completely wipe out any species within 8 to 15 generations by putting a recessive sterility gene in mosquitoes which would be benign until it reaches critical mass in the population, and makes all Male mosquitoes sterile. I believe there was a promising study done in the Florida keys about this very subject near me. I don't work directly for mosquito control so don't quote me on this but I've partnered with them several times and this seems like the most realistic way to eradicate malaria. And the ecological effect would be relatively minimal as virtually zero pesticides would be needed and in most places that I've seen Anopholes and Aedes occur they're non native as they seem to predominantly occur around human settlements and not in natural areas so the food chain would remain intact in the vast majority of cases.

  14. "We now know [DDT] is great at killing everything else." This statement is painfully un-scientific and biased. The cost of eradicating malaria in the U.S. was not "killing everything else"…it was reduced populations of Brown Pelicans & Peregrine Falcons which rebounded relatively quickly. But maybe you, like the environmental activists that hastily got life-saving DDT banned, want to avoid the tough questions surrounding accepting and mitigating the risk to some bird species to save the millions of African children that die each year from malaria.

  15. Vaccine was created in the 80s by Manuel Elkin Patarroyo in Colombia with 28% efficacy. More work should be done over that, bet new technologies can improve the vaccine.

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