Despite Mosquitoes’ Wily Evolution, Countries Make Progress Against Malaria
A young girl reads under a malaria bednet.

Wily malaria-carrying mosquitoes are biting people earlier in the day before they get under their protective bednets and sleeping outside homes to avoid insecticide – and many have developed resistance to the insecticide used to impregnate the bednets.

Despite these and other challenges, progress against malaria has been relatively steady – even during the height of the COVID-19 pandemic, according to the World Health Organization’s (WHO) annual report on malaria released on Thursday.

“Although hard hit [by COVID-19], most countries held the line and were able to maintain services to prevent, detect and treat malaria – a remarkable feat in the midst of a pandemic,” said WHO Director-General Dr Tedros Adhanom Ghebreyesus.

“There were an estimated 619 000 malaria deaths globally in 2021 compared to 625 000 in the first year of the pandemic. In 2019, before the pandemic struck, the number of deaths stood at 568 000,” the WHO said in a media release.

The African region shouldered about 95% of cases and 96% of deaths globally in 2021.

Cases slowing

Malaria cases continued to rise between 2020 and 2021, but at a slower rate than in the period 2019 to 2020. The global tally of malaria cases reached 247 million in 2021, compared to 245 million in 2020 and 232 million in 2019. 

“Following a marked increase in malaria cases and deaths in the first year of the COVID-19 pandemic, malaria-affected countries redoubled their efforts and were able to mitigate the worst impacts of COVID-related disruptions to malaria services,” said Tedros. 

“We face many challenges, but there are many reasons for hope. By strengthening the response, understanding and mitigating the risks, building resilience and accelerating research, there is every reason to dream of a malaria-free future.”

Ismail Yusuf and Awalu Iliasu inspect the offloading of mosquito nets bales during the distribution of mosquito nets in Kano State in Nigeria.

Insecticide-treated bednets (ITNs) are the primary vector control tool used in most malaria-endemic countries and, in 2020, countries distributed more ITNs than in any year on record. 

In 2021, ITN distribution was at similar levels to pre-pandemic years: 171 million ITNs planned for distribution, and 128 million (75%) were distributed. 

However, eight countries – Benin, Eritrea, Indonesia, Nigeria, Solomon Islands, Thailand, Uganda and Vanuatu – distributed less than 60% of their ITNs, and seven countries – Botswana, Central African Republic, Chad, Haiti, India, Pakistan and Sierra Leone – did not distribute any nets.

Nigeria is in the midst of the world’s biggest bednet distribution campaign to catch up.

Treatment hurdles

Malaria control efforts face many hurdles in addition to the already significant COVID-related disruptions and other health system challenges, including long-running humanitarian crises, limited donor funding, and the potential effect of climate change on the spread of the disease, according to the report.

Africa’s response to malaria is being undermined by mosquitoes developing resistance to pyrethroid-based insecticide, which has been used to impregnate bednets; insufficient access; and loss of insecticide-impregnated nets due to daily stresses, as well as the “changing behaviour of mosquitoes, which appear to be biting early before people go to bed, and resting outdoors, thereby evading exposure to insecticides”, according to the WHO.

“Other risks are also rising, including parasite mutations affecting the performance of rapid diagnostic tests; growing parasite resistance to the drugs used to treat malaria; and the invasion in Africa of an urban-adapted mosquito that is resistant to many of the insecticides used today,” according to the WHO.

The urban mosquito Anopheles stephensi has historically only been found in the Asian sub-continent and the Middle East, but is now present in some locations in Africa.

New strategies – and a vaccine

WHO recently launched two strategies to support African countries to build a more resilient response to malaria: a strategy to curb antimalarial drug resistance and an initiative to stop the spread of the Anopheles stephensi malaria vector. Additionally, a new global framework to respond to malaria in urban areas, developed jointly by WHO and UN-Habitat, provides guidance for city leaders and malaria stakeholders.

Meanwhile, a robust research and development pipeline is set to bring a new generation of malaria control tools that could help accelerate progress towards global targets.

Key opportunities include long-lasting bednets with new insecticide combinations and other innovations in vector control, including targeted baits that attract mosquitoes, spatial repellents and genetic engineering of mosquitoes. New diagnostic tests are also under development, as are next-generation life-saving medicines to respond to antimalarial drug resistance.

From late 2023 onwards, millions of children living in areas of highest risk of illness and death from malaria are also expected to benefit from the life-saving impact of the world’s first malaria vaccine, RTS,S. Although the vaccine has limited efficacy in trials, the effects are significant enough to roll it out to young children and babies in seriously affected areas.

Researchers observed a 30% reduction in severe malaria infections, a 21% reduction in hospitalisations, and a 10% reduction in mortality in the areas of Ghana, Kenya and Malawi where the vaccine was piloted on some 800,000 infants and children aged 5–17 months

Other malaria vaccines are also in the product development pipeline, and one – R21/Matrix M – is showing great potential.

According to the report, these opportunities cannot be fully exploited without intensified efforts to ensure that nobody is left behind, including strengthening the primary health systems of worst affected areas.

A healthcare worker gives a child a dose of the malaria vaccine, RTS,S.

Funding gap

However, total funding for malaria in 2021 was US$ 3.5 billion, an increase from the two previous years less than half the estimated US$ 7.3 billion required globally to stay on track to defeat malaria.

The Global Fund to Fight AIDS, Tuberculosis and Malaria, which provides 63% of all international financing for malaria programmes, said that the report showed that the world is not on track to reach the target of eliminating malaria in 30 countries by 2030.

“There are a number of reasons for this slowdown, but most obvious is the global funding gap of US$3.8 billion,” said the Global Fund. “Far from being closed, this gap has increased by US$1.2 billion increase since 2019. While the gap is very significant relative to the total funding need, it is small in comparison to the resources that have been deployed to fight COVID-19, and to the economic and social burden imposed by malaria on some of the poorest communities in the world.”

Lack of funds means “less money for research and development of new tools to fight malaria” and it also means that the Global Fund would have to “make difficult choices in the frequency and reach of our most successful campaigns, such as the distribution of nets”.

Effect of climate change

The global funding gap comes on top of the shrinking fiscal space in the most affected countries as the economic impact of converging crises and the fallout of the COVID-19 pandemic are felt around the world. 

“Malaria is not a disease that stands still,” said Peter Sands, executive director of the Global Fund. “The parasites evolve to resist treatments, and mosquitoes adapt to resist insecticides or bite their victims earlier in the day.

“Humanitarian crises lead to mass displacement and create the conditions for mosquitoes to breed and parasites to multiply. Climate change is extending the geographical reach of malaria to regions previously regarded as safe, such as highlands, and is causing disasters such as the recent massive floods in Pakistan, which have resulted in a dramatic increase in malaria cases.”

But “all these causes can be addressed with better and more sustainable funding,” said Sands.

“Better funding of R&D, for example, would support the development of tools like new insecticides, new treatments, new diagnostics to detect the evolving malaria parasites, new vaccines or the genetic modification of mosquitoes. Better funding of country programmes would allow for more frequent and wider distribution of nets, and a higher quality of net, leading households to use them for longer.”

Image Credits: Commons Wikimedia, UNDP, Global Fund, WHO/M. Nieuwenhof.

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