Be honest vegans, you hate mosquitos. If all they wanted was our blood to survive, maybe we could work something out, but they make the wound itch and shuttle diseases around–those entitled jerks. Of course, they spread deadly diseases. What do you expect from the succubus of our ecosystem? Malaria alone, being one of these diseases, killed more than half a million people in 2022.¹ Yet, it’s treatable. There are anti-malarial drugs that will treat the infection, but you need to diagnose it early and have access to the medication. That requires access to healthcare facilities that are less common in impoverished countries. It all comes together when you realize that 95% of the deaths caused by Malaria in 2022 occurred in Africa¹ and that the United States declared itself free of Malaria in 1949.² Given the inability of these impoverished regions to access healthcare seamlessly, the scientists must step in.

Three takeaways to tell your friends:

• Malaria killed over 450,000 children in 2022,¹ yet with the proper resources, it is very treatable.
• One species of mosquito, Anopheles gambiae spreads Malaria.³
• Millions of genetically-modified sterile male Anopheles gambiae eggs can be released into the wild to eliminate the population.⁴

There have been two vaccines supplied for Malaria since 2021,^(5,6) but how do we reach all the people in these areas? It seems our best bet is to eliminate the disease-causing mosquitoes. There are over 3,000 species of mosquitoes.³ Only three are known to spread diseases.³ One of those three species, Anopheles gambiae, spreads Malaria.³ In this study, using a CRISPR/Cas9 system, they attempt to eliminate this single mosquito species.⁴

CRISPR/Cas9 is a revolutionary tool that allows researchers to edit genes within organisms.⁷ Genes are patterns of DNA that become proteins like insulin and keratin. The disruption works by having the CRIPSR/Cas9 slice a gene’s DNA sequence at a specific point. Then, in an attempt to repair itself, the gene becomes misaligned.⁷ Therefore, when called upon, the gene cannot produce the protein properly and is considered deleted. Now, for this study, the goal is to produce sterile males and no females from their mating pairs. To achieve this using CRISPR/Cas9, they “deleted” two male fertility genes, one involved in sperm motility, while also “deleting” two essential female genes.⁴ This way, the offspring will consist of sterile males and no surviving females (Figure 1). It worked.

Something of note, once a female mates with a male, her vaginal opening becomes sealed with a “mating plug” preventing the female from mating again.⁴ Think of mosquitoes as monogamous: one mating partner, then babies until death. If the male were fertile, the female would continue to produce offspring from his sperm stored in her reproductive organs over her lifetime. However, in this study, the males are sterile, so the females do not produce offspring and cannot mate again, rapidly eliminating the population (Figure 1).

But how effective is the elimination? Well, the more the merrier. There is over a 90% chance of eliminating the A. gambiae population when researchers conduct ≥6 weekly releases of sterile eggs when the number of sterile eggs is calculated by multiplying the current A. gambiae population.⁴ Therefore, weekly releases and population multiplier are inversely correlated. For example, releasing eggs 20 times per week, then only releasing 24 times the current population (Table 1).⁴

Weekly Releases	Population Multiplier	Number of eggs per release	Number of eggs released each week
6	128x	240 million	1.44 billion
20	24x	45 million	900 million
16	128x	240 million	3.84 billion

This work has been modeled before in another disease-spreading mosquito species but never used in the wild.⁸ In this study, they only conducted the elimination within their lab environment or through computer simulations⁴; however, it checks out. And hopefully, soon it will be implemented in the local African regions that need it most, like Nigeria, the Democratic Republic of the Congo, Uganda, and Mozambique.¹ It’s time to rid the world of the needless insult of a treatable disease like Malaria. Let’s end the reign of the Anopheles gambiae mosquito.

If you are worried that releasing sterile male mosquitoes into the wild would increase disease spreading even temporarily, males don’t bite and therefore, cannot spread disease.

If you’re interested in learning what would happen if we completely rid the world of mosquitoes, I highly recommend this short article from HowStuffWorks.

Fun fact: did you know that Sickle cell disease can help prevent a deadly Malaria infection? Why do you think Sickle cell disease is so common in Africa? Because it helps them survive.

REFERENCES

1. World Health Organization. Malaria [Internet]. World Health Organization. WHO; 2023. Available from: https://www.who.int/news-room/fact-sheets/detail/malaria

2. Elimination of malaria in the United States (1947 — 1951). Center for Global Health (US) Division of Parasitic Diseases and Malaria [Internet]. 2018 Jul 23 [cited 2024 Sep 16]; Available from: https://stacks.cdc.gov/view/cdc/100616

3. National Geographic. Mosquitoes | National Geographic [Internet]. Animals. 2010. Available from: https://www.nationalgeographic.com/animals/invertebrates/facts/mosquitoes

4.         Apte RA, Smidler AL, Pai JJ, Chow ML, Chen S, Mondal A, et al. Eliminating malaria vectors with precision-guided sterile males. Proc Natl Acad Sci U S A. 2024;121(27):e2312456121.

5.         Willyard C. The slow roll-out of the world’s first malaria vaccine. Nature. 2022;612(7941):S48-S9.

6.         Egbewande OM. The RTS,S malaria vaccine: Journey from conception to recommendation. Public Health Pract (Oxf). 2022;4:100283.

7.         Jinek M, Chylinski K, Fonfara I, Hauer M, Doudna JA, Charpentier E. A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity. Science. 2012;337(6096):816-21.

8.         Li M, Yang T, Bui M, Gamez S, Wise T, Kandul NP, et al. Suppressing mosquito populations with precision guided sterile males. Nat Commun. 2021;12(1):5374.

‌

‌

‌