By Márcia Costa, Manager, Deloitte Centre for Health Solutions

On 20 August 1897, British doctor Sir Ronald Ross proved that malaria was transmitted by mosquitoes. World Mosquito Day is celebrated on 20 August each year to raise awareness of the dangers posed by mosquito-borne diseases and the urgent need for investment and political commitment to eradicate these diseases. This year's theme is 'Accelerating the fight against malaria for a more equitable world'. The World Health Organisation (WHO) estimated that malaria, in 2022 alone, affected almost 250 million people and killed some 608,000, mainly in sub-Saharan Africa.^[1] Climate change also poses a significant risk in increasing the transmission of malaria and could increase the inequity of impact across the globe. This week’s blog explores the inequitable high burden of malaria the current approach to reducing this burden and some of the exciting innovations that could prove to be game changers in creating a malaria-free world.

Mosquitos and malaria

There are more than 3,000 species of mosquito but less than ten percent are known likely or potential vectors for human disease.^[2] Malaria is a parasitic disease that spreads through the bites of infected female Anopheles mosquitoes carrying Plasmodium parasites. There are five species known to infect humans: P. falciparum (the deadliest parasite and most prevalent in Africa), P vivax (dominant in most countries outside of sub-Saharan Africa), P. malariae, P. ovale and P. knowlesi. Currently, malaria is mostly found in tropical regions, particularly Africa but also South America, South Asia and certain Oceania regions. It is endemic in 85 countries or areas, mosly low- and middle-income countries (LMICs).^[3]

Symptoms include fever, ache and chills and can be milder for certain groups of people, such as those who have been infected before. However, other, including infants and children younger than 5 years, pregnant women and people with HIV/AIDS, are at high risk of complications such as severe malaria – extreme tiredness and fatigue, impaired consciousness, convulsions, difficulty breathing, jaundice and abnormal bleeding – and death.

The impact of poverty and climate change

Malaria constitutes a significant global health challenge with an estimated 249 million cases worldwide in 2022. Sub-Saharan Africa accounted for 94 per cent of malaria cases and 95 per cent of deaths (580,000). Children under five represent some 80 per cent of these deaths. Importantly, malaria case incidence declined from 81.0 per 1,000 population at risk in 2000, to 58.4 in 2022; and the mortality rate has halved since 2000, from 28.8 per 100,000 population at risk to 14.3.^[4] These improvements are due to advances in prevention (including vaccination, seasonal malaria chemoprevention (administering monthly doses of antimalarial drugs to children aged 3-59 months during the peak malaria transmission season) and other methods that reduce the contact between humans and mosquitoes such as residual indoor spraying with insecticides and insecticide-treated nets. There have also been advances in diagnostics and more effective treatments. However, there remains an urgent need for more investment in surveillance and innovative approaches to eradicating the disease.

Malaria is a disease of poverty, with poverty being both a cause and a consequence of malaria. Poverty creates conditions that increase vulnerability to malaria. such as:

• poor housing lacking adequate protection from mosquitoes (such as closed eaves, ceilings and screened doors and windows)
• malnutrition making individuals more susceptible to malaria infection and increasing the likelihood of developing severe complications
• lower education levels
• limited healthcare access.

In turn, malaria deepens poverty through the financial burden due to treatment costs, lost productivity, and long-term health impacts.^[5] Therefore, the malaria burden not only leads to high morbidity and mortality, but also hinders economic development and perpetuates cycles of poverty.

Another major factor contributing to the persistence of malaria is climate change. Warmer temperatures and changes in rainfall patterns result in increased vector survival and biting rates and replication of pathogens within vectors, shorter reproduction rates, longer transmission seasons, and create ideal breeding grounds (such as water pools) for mosquitos. Climate change is expanding the geographical range of malaria-carrying mosquitoes, increasing the risk of transmission in previously unaffected areas. A modelling study by researchers from the UK, Germany, Sweden and Italy published int The Lancet Planetary Health in 2021 estimated that, with current trends, warmer climates will increase the amount of time during which temperatures will be suitable for malaria transmission by 1.6 months in tropical highlands in the African region, the Eastern Mediterranean region, and regions of the Americas, increasing the population at risk of malaria by up to 3.6 billion additional people by 2071.^[6]

To further complicate matters, Anopheles mosquitoes are widely adaptable and are becoming increasingly resistant to pyrethroid, the most commonly used insecticide in treated nets.^[7] These change in patterns and behaviours of mosquitoes, and the significant increased risks, together with the link between malaria and poverty adds further impetus to the need for more effective interventions to prevent malaria and reduce health inequities.

How innovation is transforming the fight against malaria

In 2019, the first malaria vaccine (RTS,S, against P. falciparum transmission) was introduced in five African countries for children aged 5-17 months. Latest data indicate than almost 2 million children have been vaccinated.^[8] This vaccine can reduce malaria cases in 39 per cent, severe malaria cases by 31.5 per cent, and also reduce hospitalisations and the need for blood transfusions.^[9] In 2023, a second vaccine (R21), with an efficacy of 75 per cent, was also recommended for children at risk.^[10]

Although vaccines provide hope that malaria cases and deaths can be substantially reduced in the future, they come with challenges, including limited capacity production and vaccine hesitancy.^[11] Therefore, it is crucial to ensure the affordability and implementation of immunisation programmes, as well as implementing community engagement programmes, in endemic regions.  Moreover, next-generation malaria vaccines could also provide better protection than current vaccines. The current R&D pipeline includes vaccines with mRNA-lipid nanoparticle technology. Vaccines based on this technology can be manufactured quickly, are expected to be safer and effective for young infants and pregnant women (two high-risk malaria groups).^[12]

In addition to vaccines, some of the more recent innovations on vector control to stop malaria transmission include:

• Genetically modified mosquitos: either through paratransgenesis, using bacteria to infect the mosquito and limit the growth of malaria parasites, or engineering of genetically modified mosquitos resistant to the malaria parasite that, when released, mate with wild mosquitos, passing on this resistance to their offspring.^[13] These techniques have been trialled since 2022.

• Advances in mosquito traps that mimic human scent: attracting mosquitos to these traps to effectively capture and kill large numbers of mosquitos, significantly reducing their population in targeted areas.^[14]

• New insecticide-treated nets: traditional nets have used pyrethroids insecticides. Innovations in LLINs now offer nets treated with new insecticides, particularly pyrethroid-chlorfenapyr combination. Chlorfenapyr LLINs have been shown to provide significantly better protection than pyrethroid-only LLINs and are strongly recommended by the WHO since 2023.^[15]

• Improved identification of mosquitos: bioengineers at Johns Hopkins University are using computer vision to identify mosquitos. Using a lens attached to a smartphone to take a picture of the mosquito a complementary app that distinguishes the different species that transmit malaria and, if the insect is female, whether it has recently fed on blood or developed eggs.^[16]

• Long-acting injectable medicines (LAIs): scientists are exploring LAIs, which could provide months of protection (rather than the current daily cocktail of tablets where adherence is very mixed) with results expected from late-stage LAI trials by 2028.[^17]

• Drones and AI in larval source management: these technology approaches are beginning to be used to help find and attack mosquito breeding sites more effectively, aimed at cutting off malaria at its source and is expected to become an increasingly important tool in eradicating malaria.^[18]

Conclusion

Although significant strides have been made in reducing malaria incidence and mortality, disparities persist, particularly in sub-Saharan Africa. Innovation plays an important role, particularly as mosquitos become resistant to traditional pesticides, and climate change alters their patterns of reproduction and geographic spread. While there are a number of promising innovations on the horizon, poverty reduction, improved healthcare access, and climate change mitigation efforts will also be crucial to reduce malaria's burden and create a more equitable future.

Márcia Costa - Manager, Centre for Health Solutions

Márcia is the research manager for healthcare in the Centre for Health Solutions, providing support and expertise to develop solutions to overcome today’s healthcare challenges. Working with the team, Márcia develops insights based on rigorous data analysis to improve outcomes for patients and increase health systems efficiencies. Originally from Portugal, Márcia has an MSc in biomedical engineering and biophysics and a PhD in cancer research. Márcia has previously worked in publishing for an oncology journal in London. Márcia is passionate about health equity.

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[1] World malaria report 2023 (who.int)

[2] https://www.nationalgeographic.com/animals/invertebrates/facts/mosquitoes

[3] https://www.who.int/news-room/fact-sheets/detail/malaria

[4] World malaria report 2023 (who.int)

[5] https://www.undp.org/blog/poverty-and-malaria-are-linked-can-we-tackle-them-together

[6] https://www.thelancet.com/journals/lanplh/article/PIIS2542-51962100132-7/fulltext

[7] https://malariajournal.biomedcentral.com/articles/10.1186/s12936-023-04554-x

[8] 18 million doses of first-ever malaria vaccine allocated to 12 African countries for 2023–2025: Gavi, WHO and UNICEF

[9] https://www.who.int/news-room/questions-and-answers/item/phase-3-trial-results-for-malaria-vaccine-rtss-as01

[10] WHO recommends groundbreaking malaria vaccine for children at risk

[11] Malaria vaccines: a test for global health (thelancet.com)

[12] A new landscape for malaria vaccine development | PLOS Pathogens

[13] How genetically modifying mosquitoes could strengthen the world’s war on malaria (theconversation.com)

[14] https://www.gatesnotes.com/Great-news-for-mosquito-haters

[15] https://www.who.int/news/item/14-03-2023-who-publishes-recommendations-on-two-new-types-of-insecticide-treated-nets

[16] https://www.gatesnotes.com/Computer-vision-is-helping-fight-malaria?WT.mc_id=20240818130000_Mosquito-Week-2024_PTR-SOC

[17] https://www.gatesnotes.com/Great-news-for-mosquito-haters

[18] Ibid.