Bill Gates has repeatedly drawn attention to this uncomfortable fact. Through his public advocacy and the work of the Gates Foundation, malaria eradication has remained firmly on the international agenda. Gates argues that the objective should extend beyond simply controlling malaria: advances in vaccines, drugs, mosquito control, surveillance and genetics could create a realistic possibility of eradicating the disease within the next two decades.
It is an extraordinarily ambitious proposition.
But first we need to understand the scale of the problem.
According to the World Health Organization’s World Malaria Report 2025, there were an estimated 282 million malaria cases and 610,000 deaths in 2024, across 80 malaria-endemic countries.
The WHO African Region accounted for approximately 94% of cases and 95% of deaths. Around three quarters of malaria deaths in Africa occurred in children under five.
Five countries — the Democratic Republic of the Congo, Ethiopia, Mozambique, Nigeria and Uganda — accounted for more than half of global malaria cases.
Yet malaria represents only one part of a much larger story.
Different mosquitoes carry different pathogens. Some transmit parasites; others transmit viruses. One can cause malaria, another dengue fever and another West Nile virus.
And one mosquito-borne infection can interfere with the development of an unborn child.
To understand the global mosquito problem, therefore, we need to understand both the mosquito and what it carries.
Malaria: A Parasite Delivered by a Mosquito
It is worth establishing an important distinction from the outset.
Mosquitoes do not actually cause malaria.
Malaria is caused by microscopic Plasmodium parasites, transmitted predominantly between humans through the bite of infected female Anopheles mosquitoes.
Five Plasmodium species cause malaria in humans.
Plasmodium falciparum
This is the most dangerous form and is responsible for most severe disease and malaria deaths, particularly in Africa.
Plasmodium vivax
This is particularly important across Asia, Latin America and parts of the Western Pacific.
Unlike P. falciparum, P. vivax can leave dormant parasite stages within the liver, allowing malaria to recur months after the original infection.
Plasmodium ovale
This can similarly produce dormant liver stages and subsequent relapses.
Plasmodium malariae
This generally produces less aggressive disease but can persist for prolonged periods.
Plasmodium knowlesi
Originally associated principally with macaques, this zoonotic malaria parasite has become an important cause of human infection in parts of Southeast Asia.
Of these, P. falciparum and P. vivax represent the greatest global public-health threats.
The mosquito is therefore the vector.
The Plasmodium parasite is the disease-causing organism.
Where Is the Malaria Belt?
Malaria is sometimes perceived from a European perspective as essentially an African disease.
That is incorrect.
Sub-Saharan Africa unquestionably carries the overwhelming burden, but malaria transmission also occurs across parts of:
South Asia
Southeast Asia
the Western Pacific
the Eastern Mediterranean
Central America
South America and the Amazon basin
Malaria transmission currently occurs across 80 countries in five WHO regions.
Interestingly, the WHO European Region has been considered malaria-free since 2015.
This illustrates an important point.
The existence of mosquitoes does not inevitably mean malaria.
Malaria transmission depends upon a relationship between:
mosquito + parasite + human host + environment.
Housing, drainage, healthcare, poverty, conflict, climate, public-health surveillance and access to treatment all influence whether that relationship becomes established.
Malaria once occurred extensively in parts of Europe and North America.
It was eliminated.
The biology did not suddenly disappear.
Human beings changed the environment in which that biology operated.
Not All Mosquitoes Are Equal
There are thousands of mosquito species worldwide, but only a relatively small proportion are significant vectors of human disease.
Three groups are particularly important:
Anopheles
Aedes
Culex
And they present very different threats.
| Mosquito group | Important diseases |
| Anopheles | Malaria, some lymphatic filariasis, O’nyong’nyong virus |
| Aedes | Dengue, yellow fever, Zika, chikungunya, Rift Valley fever, some lymphatic filariasis |
| Culex | West Nile fever, Japanese encephalitis, lymphatic filariasis |
This distinction becomes crucial when considering how mosquito-borne disease should be prevented.
Anopheles: The Malaria Mosquito
Anopheles mosquitoes are the principal vectors of human malaria.
Many important malaria vectors predominantly bite during the evening and night.
That behavioural characteristic explains why one extraordinarily simple intervention has saved so many lives:
The insecticide-treated bed net.
A mosquito attempting to reach a sleeping person encounters both a physical barrier and an insecticide.
More than three billion insecticide-treated nets have been delivered to malaria-endemic countries, and WHO considers their rapid deployment the largest contributor to the dramatic reduction in malaria incidence achieved since the beginning of this century.
Sometimes extremely effective medicine is remarkably simple.
Aedes: The Urban Mosquito
If Anopheles represents the classic malaria mosquito, Aedes represents a different and increasingly important threat.
Two species deserve particular attention:
Aedes aegypti
and
Aedes albopictus, commonly known as the Asian tiger mosquito.
Aedes mosquitoes can transmit:
Dengue
Yellow fever
Chikungunya
Zika
and several other infections.
Dengue alone demonstrates the enormous scale of the problem. WHO estimates that approximately 3.9 billion people across more than 130 countries are at risk.
Unlike many important malaria vectors, Aedes mosquitoes frequently bite during the day.
This immediately changes prevention.
A bed net provides excellent protection against a mosquito attempting to bite someone while asleep.
It provides considerably less protection against a mosquito biting somebody outdoors at two o’clock in the afternoon.
Aedes mosquitoes have also adapted extremely successfully to human settlements.
Buckets.
Plant pots.
Discarded containers.
Water-storage vessels.
Drainage systems.
Old tyres.
Even relatively tiny collections of standing water can provide breeding opportunities.
Paradoxically, therefore, the modern city can create an excellent mosquito habitat.
Zika: When the Victim Has Not Yet Been Born
Perhaps no modern epidemic demonstrated the extraordinary consequences of mosquito-borne disease more dramatically than the Zika epidemic associated particularly with the Americas in 2015–16.
Zika virus is principally transmitted by Aedes aegypti, although Aedes albopictus can also transmit the virus.
For most infected adults, the illness is surprisingly mild.
Most infected people develop no symptoms.
Those who do may experience fever, rash, conjunctivitis, muscle and joint pain, headache and general malaise.
Pregnancy transforms the significance of the infection.
Zika virus can pass from an infected pregnant woman to her developing fetus.
The consequences can be devastating.
Maternal infection can cause congenital Zika syndrome, which may include:
Microcephaly
Abnormal brain development
Limb contractures
Abnormally increased muscle tone
Eye abnormalities
Hearing impairment
and other neurological and developmental abnormalities.
Zika infection during pregnancy has additionally been associated with miscarriage, fetal loss, stillbirth and premature delivery.
WHO estimates that approximately 5–15% of infants born to women infected with Zika during pregnancy show evidence of Zika-related complications, although the precise risk remains uncertain.
Importantly, congenital abnormalities can occur following both symptomatic and asymptomatic maternal infection.
This means a pregnant woman does not necessarily have to become noticeably ill for the developing fetus to be affected.
The Brazilian Warning
The significance of Zika became dramatically apparent when clinicians in Brazil observed an unusual increase in babies being born with microcephaly.
The relationship between Zika infection during pregnancy and congenital abnormalities was subsequently established.
In February 2016, WHO declared the clusters of Zika-associated microcephaly and neurological disease a Public Health Emergency of International Concern.
There was another complication.
Zika is unusual among the major mosquito-borne infections because it can also be sexually transmitted.
Transmission can therefore potentially occur without the pregnant woman herself ever being bitten by an infected mosquito.
This has implications for couples planning pregnancy and for those undergoing IVF and other assisted reproductive treatment, particularly following residence in or travel to areas where Zika transmission is occurring.
The Zika epidemic demonstrated an extraordinary biological paradox:
A mosquito-borne infection capable of causing little or no illness in an adult can profoundly affect the neurological development of an unborn child.
Culex: The Overlooked Third Group
The third important mosquito group is Culex.
Culex species transmit several significant diseases, including:
West Nile virus
Japanese encephalitis
Lymphatic filariasis
West Nile illustrates a particularly interesting transmission cycle.
Birds act as important reservoir hosts. Mosquitoes feed upon infected birds and subsequently transmit infection to other animals.
Humans and horses can become infected but generally act as incidental or “dead-end” hosts because they do not normally develop sufficient circulating virus to continue the transmission cycle.
Japanese encephalitis presents another ecological relationship involving mosquitoes, water birds, pigs and humans.
It remains an important disease across parts of Asia. WHO estimates approximately 100,000 clinical cases annually, and severe encephalitis can carry a mortality rate approaching 30%.
Once again, “the mosquito” is not a single problem.
Different species occupy different ecological niches and carry completely different pathogens.
How the World Fights Malaria
There is no single solution to malaria.
Successful malaria management instead depends upon layers of protection.
These include:
Insecticide-treated bed nets
Indoor residual spraying
Environmental and larval control where appropriate
Rapid diagnostic testing
Effective antimalarial treatment
Preventive antimalarial medication
Vaccination
Disease surveillance
Mosquito surveillance
Improved housing and infrastructure
The objective is not simply to kill mosquitoes.
It is to repeatedly interrupt the transmission cycle.
Vaccinating Against Malaria
One of the greatest recent advances has been the development of effective malaria vaccines.
WHO currently recommends two:
RTS,S/AS01
and
R21/Matrix-M.
They are recommended for preventing P. falciparum malaria in children living in malaria-endemic areas, with priority given to areas of moderate and high transmission.
Malaria vaccination has now been introduced into routine programmes in more than 20 African countries.
This represents an extraordinary scientific achievement.
Plasmodium is a complicated parasite passing through several stages of development rather than a comparatively simple virus.
But vaccination is not intended to replace mosquito nets, medicines or surveillance.
It becomes another defensive layer.
A child who receives vaccination, sleeps beneath an effective insecticide-treated net and has rapid access to diagnosis and treatment possesses several independent layers of protection.
That is considerably more powerful than relying upon any single intervention.
The Mosquito Fights Back
There is, however, an evolutionary problem.
For many years insecticide-treated nets relied predominantly upon pyrethroid insecticides.
Mosquitoes began developing resistance.
The mechanism is straightforward natural selection.
Susceptible mosquitoes die.
Mosquitoes carrying characteristics that enable them to survive reproduce.
Those characteristics become increasingly common within subsequent generations.
The response has included dual-active-ingredient mosquito nets.
One example highlighted by the Gates Foundation combines the established pyrethroid approach with chlorfenapyr, which attacks mosquitoes through a different biological mechanism.
By attacking the mosquito in more than one way, these nets can remain effective against mosquito populations in which pyrethroid resistance has developed.
Bill Gates and the Gates Foundation deserve particular credit for bringing public attention and significant financial support to innovations of this kind.
The Parasite Fights Back Too
Unfortunately, mosquitoes are not the only organisms evolving.
Plasmodium does exactly the same thing.
Drug-resistant malaria has repeatedly emerged during the history of malaria treatment.
Today, artemisinin-based combination therapies remain central to treatment of P. falciparum malaria.
But partial resistance to artemisinin derivatives is an increasing concern.
WHO now describes antimalarial drug resistance as a significant threat to global malaria control and elimination.
The relationship therefore becomes an evolutionary arms race:
We develop an insecticide.
The mosquito evolves resistance.
We develop a drug.
The parasite evolves resistance.
Simply inventing another chemical each time is unlikely to provide a permanent solution.
That is one reason researchers are investigating much more radical approaches.
Attacking Malaria Through Genetics
This is perhaps the most fascinating — and controversial — aspect of the work supported by the Gates Foundation.
Researchers are investigating genetically based mosquito control.
One potential approach is to modify malaria-transmitting mosquitoes so they become less capable of reproducing.
Another is to alter them so they can no longer efficiently transmit the malaria parasite.
The most ambitious technology is known as gene drive.
Under normal Mendelian inheritance, an altered genetic characteristic may be inherited by approximately half an organism’s offspring.
Gene-drive technology attempts to bias that inheritance dramatically.
A selected characteristic could therefore spread through a mosquito population much faster than conventional inheritance would allow.
In principle, researchers might introduce a characteristic that suppresses a malaria-vector population or prevents it effectively transmitting Plasmodium.
Gates discussed the technology publicly as early as 2018 and again at the Gates Foundation’s Grand Challenges meeting in 2023.
Research associated with Target Malaria has subsequently progressed through laboratory work, while African scientists and institutions are increasingly central to determining whether and how such technologies could eventually be evaluated in malaria-endemic countries.
The potential is enormous.
So are the questions.
What are the ecological consequences?
Could the genetic change spread farther than intended?
Could mosquitoes or parasites evolve around it?
Can an intervention be reversed?
Who decides whether genetically altered mosquitoes should be released?
And how is meaningful community consent achieved when mosquitoes recognise neither village boundaries nor national borders?
The technology therefore deserves neither sensationalist rejection nor unquestioning enthusiasm.
It deserves rigorous science.
Gene-drive mosquito control remains experimental, not an established malaria-control intervention.
But if it proves safe and effective, it could fundamentally alter the relationship between humans, mosquitoes and malaria.
Control, Elimination and Eradication
Three terms need to be distinguished.
Control means reducing disease incidence and mortality to manageable levels.
Elimination means stopping local transmission within a particular geographical area.
Eradication means permanently reducing worldwide transmission to zero.
Smallpox has been eradicated.
Malaria has not.
WHO’s Global Technical Strategy for Malaria 2016–2030 established four major targets for 2030:
Reduce malaria incidence by at least 90%.
Reduce malaria mortality by at least 90%.
Eliminate malaria in at least 35 countries.
Prevent malaria becoming re-established in countries that are malaria-free.
The world is not currently on course to achieve all of those objectives.
Yet the progress already achieved is extraordinary.
WHO estimates that since 2000 approximately 2.3 billion malaria cases and 14 million deaths have been averted.
Forty-seven countries and one territory have now been certified malaria-free by WHO.
Malaria interventions were estimated to have saved approximately one million lives in 2024 alone.
The paradox is striking.
Humanity has become extraordinarily good at preventing malaria.
Yet 610,000 people still died from it in a single year.
Poverty Is Part of the Disease
Perhaps malaria’s greatest lesson is that it cannot be understood simply as tropical biology.
Imagine two houses located within the same climatic region.
One has sealed windows, insect screens, reliable drainage, air conditioning and immediate access to healthcare.
The other has open windows, standing water nearby, limited access to mosquito nets and a clinic several hours away.
The temperature is identical.
The mosquito may be identical.
The malaria risk is not.
Malaria thrives where biological vulnerability intersects with:
poverty
poor housing
weak healthcare
inadequate sanitation and drainage
conflict
population displacement
and limited public-health infrastructure.
War can dismantle decades of malaria control extraordinarily quickly.
Climate creates an opportunity.
Poverty often determines how effectively human beings can defend themselves against it.
Climate Change Adds Another Variable
Mosquito biology is closely connected to environmental conditions.
Temperature affects mosquito development.
Rainfall influences breeding habitat.
Humidity influences mosquito survival.
Temperature can also affect the rate at which pathogens develop inside the mosquito.
As climatic conditions change, mosquito distributions can change with them.
Aedes albopictus is particularly interesting because it tolerates cooler climates better than Aedes aegypti and has expanded far beyond its historical Asian range.
That does not mean tropical mosquito-borne diseases will automatically become endemic everywhere the mosquito appears.
The vector must be present.
The pathogen must be introduced.
Environmental conditions must permit transmission.
Enough susceptible hosts must exist.
And transmission must be sustained.
Nevertheless, expanding vector ranges create additional opportunities for disease.
Surveillance consequently becomes increasingly important.
Perhaps We Have Been Asking the Wrong Question
The conventional question is:
How do we eradicate malaria?
Perhaps the larger question should be:
How do we manage mosquitoes as global disease vectors?
Malaria demonstrates what happens when Anopheles mosquitoes transmit Plasmodium.
Dengue demonstrates what happens when Aedes mosquitoes transmit a virus extraordinarily effectively through densely populated communities.
West Nile demonstrates how mosquitoes can connect wildlife reservoirs with human disease.
Japanese encephalitis demonstrates the interaction between mosquitoes, animals, agriculture and human populations.
And Zika demonstrates something more disturbing still.
The person suffering the greatest consequences of a mosquito bite may not be the person who was bitten.
It may be their unborn child.
Mosquito-borne disease therefore sits at an extraordinary intersection of:
entomology
parasitology
virology
genetics
climate
economics
medicine
public health
and human behaviour.
Bill Gates deserves considerable credit for keeping malaria eradication prominent on the international agenda and for supporting investment in improved mosquito nets, vaccines, drugs, surveillance and experimental genetic vector-control technologies.
But the wider lesson extends beyond malaria.
Humanity is not fighting a single mosquito.
Nor are we fighting a single disease.
We are attempting to interrupt numerous biological relationships between mosquito, pathogen and human host, each operating within changing environmental and socioeconomic conditions.
And we already know that these relationships can be broken.
Since 2000, billions of malaria infections have been prevented and millions of lives saved.
Countries that once suffered endemic malaria have eliminated it.
The question is therefore no longer simply whether humanity possesses the scientific ability to defeat malaria.
Increasingly, the question is whether the world can maintain the funding, healthcare infrastructure, surveillance, scientific innovation and political commitment necessary to finish the job.
Bill Gates told African leaders in 2025 that, with the technologies now emerging and African scientists increasingly leading their development, he believed there was a real possibility of completely eradicating malaria within the following twenty years.
If that prediction proves correct, it would represent one of the greatest achievements in the history of public health.
And perhaps demonstrate something even more important:
One of the smallest creatures on Earth need not remain one of humanity’s greatest killers.
Sources and Further Reading
World Health Organization — World Malaria Report 2025
The principal source for current global malaria incidence, mortality, geographical distribution, trends, drug resistance and progress towards elimination.
WHO reports approximately 282 million cases and 610,000 deaths during 2024 and estimates that 2.3 billion cases and 14 million deaths have been prevented since 2000.
World Health Organization — Global Technical Strategy for Malaria 2016–2030
WHO’s international framework for malaria control and elimination, including the targets of reducing incidence and mortality by at least 90% by 2030.
World Health Organization — Guidelines for Malaria
WHO’s consolidated evidence-based recommendations covering prevention, vector control, preventive medicines, diagnosis, treatment, vaccination and elimination.
World Health Organization — Malaria Vaccines: RTS,S and R21
WHO guidance covering the RTS,S/AS01 and R21/Matrix-M vaccines and their use for prevention of P. falciparum malaria in children living in endemic areas.
World Health Organization — Vector-Borne Diseases
Useful wider reference covering the principal mosquito vectors and the diseases associated with Anopheles, Aedes and Culex.
World Health Organization — Zika Virus
Reference for Aedes-borne Zika transmission, congenital Zika syndrome, microcephaly, pregnancy complications and sexual transmission.
World Health Organization — Japanese Encephalitis
Background on Culex-transmitted Japanese encephalitis, its distribution across Asia, disease burden and vaccination.
Gates Foundation — Malaria Programme
The Foundation’s overview of its malaria-eradication strategy, including surveillance, drug and insecticide resistance, next-generation treatments and novel vector-control technologies.
Bill Gates — Address to the African Union, 2025
Gates discusses emerging mosquito-control technologies and his belief that advances currently being developed could create a realistic possibility of eradicating malaria within the next twenty years.
Bill Gates — Grand Challenges Annual Meeting, 2023
Gates discusses the development of genetic mosquito-control technology, Target Malaria and the potential application of gene-drive approaches against malaria vectors.
Gates Foundation — Next-Generation Mosquito Nets
Material examining the development of dual-insecticide mosquito nets, including technologies designed to overcome increasing pyrethroid resistance.
Gates Foundation / Target Malaria — Gene-Drive Research
Background on genetically based vector control and research into mosquitoes engineered either to suppress malaria-vector populations or reduce their ability to transmit Plasmodium.
Principal online references
World Health Organization — World Malaria Report 2025
https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2025
World Health Organization — Malaria
https://www.who.int/health-topics/malaria
World Health Organization — Global Technical Strategy for Malaria
https://www.who.int/teams/global-malaria-programme/global-technical-strategy-for-malaria-2016-2030
World Health Organization — Malaria Vaccines
https://www.who.int/news-room/questions-and-answers/item/q-a-on-rts-s-malaria-vaccine
World Health Organization — Vector-Borne Diseases
https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases
World Health Organization — Zika Virus
https://www.who.int/news-room/fact-sheets/detail/zika-virus
World Health Organization — Japanese Encephalitis
https://www.who.int/news-room/fact-sheets/detail/japanese-encephalitis
Gates Foundation — Malaria
https://www.gatesfoundation.org/our-work/programs/global-health/malaria
Gates Foundation — 2025 Goalkeepers Report
https://www.gatesfoundation.org/goalkeepers/report/2025-report/
Gates Foundation — Bill Gates’ African Union Address, 2025
https://www.gatesfoundation.org/ideas/speeches/2025/06/bill-african-union
Gates Foundation — Bill Gates, Grand Challenges Annual Meeting
https://www.gatesfoundation.org/ideas/speeches/2023/10/bill-grand-challenges-dakar
Acknowledgement: This article draws upon epidemiological data and public-health guidance published by the World Health Organization. Bill Gates and the Gates Foundation are credited specifically for their public advocacy of malaria eradication and their support and communication of research into next-generation mosquito nets, malaria vaccines, medicines, surveillance and genetically based vector-control technologies.
The core statistics are from the WHO’s latest malaria reporting: 282 million cases, 610,000 deaths and 80 endemic countries in 2024, with Africa carrying 94% of cases and 95% of deaths. The Zika section follows WHO’s current position that infection during pregnancy can cause congenital Zika syndrome and that both Aedes aegypti and Aedes albopictus can transmit the virus. Gates’ contribution is deliberately credited rather than treated as the source of the WHO epidemiology; his Foundation’s material supports the sections on next-generation nets and gene-drive research.
