Guest post by Kip Hansen
You would think that science journalists have been carefully trained to research the topics they write about, especially in popular media like New York Times. It’s a pity that relying on careful background is a thing of the past even in these prestigious newsrooms.
“A new study offers a glimpse into the future by looking into the past. According to the study, the mosquitoes that transmit malaria in sub-Saharan Africa migrate to higher altitudes about 6.5 meters (about 21 feet) each year and 4.7 kilometers (about 3 miles) away from the Equator each year. in the past century. “
“That rate is consistent with climate change and may explain why malaria’s range has expanded over the past few decades,” the authors said. The results have serious implications for countries that are not prepared to deal with this disease.”
The article was motivated by a recent study (yes, “There is a study!”) that appeared in Biology letter with the title: “Rapidly changing range of the African Anopheles mosquito over the past century“ by Carlson et al. (2023).
This study claims to have found “Mosquitoes that transmit malaria in sub-Saharan Africa migrate to higher altitudes about 6.5 meters (about 21 feet) per year and 4.7 kilometers (approximately) from the Equator.” three miles) per year for the past century, according to the study.
I’m not going to argue with their actual findings… that’s the result of rather confusing computations on heterogeneous data sets. But we caught the lead author, Colin Carlson, quoting this quote for Time:
“If this were random and if it wasn’t climate related, it wouldn’t appear to be clearly climate related.”
Ours time Journalist, Mandavilli, said, “A new study offers a glimpse into the future by looking to the past.”
Unfortunately, the authors or Mandavilli don’t seem to have looked far enough or close enough into the past to realize that their conclusions and worries are not supported by real-world historical events. Other epidemiologists have noticed, as reported in the “Discussion” section of the article:
“Others have disputed these conclusions, suggesting that they are not reconciled with the long-term progress towards malaria elimination, that regional trends are better explained by control programs have lapsed and resistance is increasing, and that climate change is inconsistent with long-term trends at the continental scale.”
And these others were quite right in refuting the conclusions, which completely ignored a number of important facts:
1) The concern is not that Africans can get bitten by mosquitoes – they will always and almost everywhere in Africa (with the exception of the Sahara and other northern deserts). It is about the location of the mosquito that transmits African malaria (Anopheles spp.).
2) But where is the real historical data on where in Africa malaria is a threat — where is malaria endemic?
That map is the Malaria Transmission Line – not just where Anopheles mosquitoes live. That shows the history of malaria transmission in Africa since 1900.
And closer to today?
This map shows where species is a reservoir for malaria has actually been found to have malaria in the blood – that is, the individual has malaria or is a carrier of malaria.
What species is that?
“Reservoir: People are the only important reserve malaria in humans. Mode of transmission: Malaria is transmitted by the bite of an infected female Anopheles mosquito. Transfusion of blood from infected individuals and the use of contaminated needles and syringes are other potential modes of transmission. April 2, 2014 Georgia Malaria Fact Sheet” (.pdf)
~ ~ ~ ~ ~
Reservoir and vector in malaria
Humans are reservoirs for malaria – The causative agent of malaria is the amoeba of the parasite parasites group (there are several) – Malaria transmission vector is one Anopheles mosquito – The host of malaria is, again, Human, who becomes part of the Reservoir.
~ ~ ~ ~ ~
3) It’s not that malaria spread around the world because Anopheles mosquito?
Incorrect:
“GLOBAL SAGA OF Malaria BILLION“
“Malaria occupies a special place in the annals of history. Over the millennia, its victims included Neolithic inhabitants, early Chinese and Greeks, princes, and the poor. In the 20th century alone, malaria claimed the lives of 150 million to 300 million people, accounting for 2 to 5% of all deaths (Carter and Mendis, 2002). Although its main sufferers today are the poor in sub-Saharan Africa, Asia, the Amazon Basin and other tropical regions, 40% of the world’s population still live in areas where it is endemic. malaria.”
“The arrival of malaria in Rome in the first century AD was a turning point in European history. From the African rainforest, the disease most likely traveled down the Nile to the Mediterranean, then east to the Fertile Crescent and north to Greece. Greek traders and colonists brought it to Italy. From that, Roman soldiers and merchants would eventually carry it as far north as England and Denmark (Karlen, 1995).”
“For the next 2,000 years, wherever Europe had crowded settlements and stagnant water, malaria flourished, leaving people with seasonal illness, weakness, and chronic lethargy. “
From : “Save Lives, Buy Time: The Economics of Malaria Drugs in the Age of Resistance”
Historically, malaria has been spread by movement of people – carriers of the malaria parasite and people who unknowingly transmit malaria-transmitting mosquitoes to new locations.
4) But not malaria is eliminated by elimination Anopheles mosquito?
No, not exactly. Perhaps not at all. Here is a map of malaria deaths in the United States in 1870:
Malaria deaths are as far north as Michigan, above Chicago and even some in Vermont.
When was it removed?
With this outbreak, we found that malaria was not eliminated in the United States in some areas until late 1965. How do we eliminate malaria? Kill all mosquitoes?
Are not.
The Anopheles quadrimaculatus mosquitoes are found today in a wide range east of the Rocky Mountains, but malaria has been completely eliminated.
How? By isolating people with malaria until their blood is free of parasites. Humans are reservoirs of malariano malaria people, mosquitoes have nothing to spread.
Note: Occasionally, travelers returning to the United States become ill with malaria in the Caribbean or Africa or other malarial areas. Once they are identified, they hospital treatment with antimalarial drugs. Malaria is a “nationally declared disease”, which means that doctors and hospitals are required/encouraged to report cases to the government. CDC.
5) In areas prone to outbreaks of mosquito-borne diseases, and in some areas, monitoring mosquito problem areas and spraying insecticides is an important public health effort. Outbreaks often stem from “ineffective control programs” — does not maintain state, county, and city insecticide spray programs. activists and lack of funding are the two most common reasons for spray discontinuation.
Bottom line:
1. Humans, not mosquitoes, are the reservoir for malaria. Humans with malaria transmit malaria. Historically, human commercial, exploratory, and military movements have been responsible for the worldwide spread of malaria. Mosquitoes are the only mediators of malaria transmission from one sick person to another (sometimes many).
2. Malaria is eliminated by treating people and preventing people with malaria from being bitten by mosquitoes, which transmit the disease.
3. Claims that an expansion or small change in the size of the habitat or the location of many Anopheles mosquitoes is a “new threat” to the people of Africa that could somehow, after centuries, be “unprepared to deal with the epidemic” is unfounded and alarming.
# # # # #
Author’s comments:
This is not my first time writing about Malaria and other mosquito-borne diseases are here.
I spent a day and a half on this essay — Apoorva Mandavilli at time write a story every few weeks. Maybe she has another job that I don’t know about. But perhaps she could have studied the history of malaria and determined that the study found no other threat to humanity.
Experts say Mandavilli at least includes this warning: “Some mosquito migration could also be due to changes in land use, food availability or a side effect of people’s migration. to higher elevations due to climate change. However, disease-carrying mosquitoes are a serious concern in areas where people and institutions are unprepared.” Or Africa’s rapidly growing population just needs somewhere to farm and live.
Thanks for reading.
# # # # #
Related
