Forty-two countries or territories have been certified as malaria-free by the World Health Organization (WHO). This has largely been credited to the use of bed nets and insecticides, alongside efficient diagnoses and treatments for the parasitic condition.
But with climate change creating new breeding grounds for malaria-carrying mosquitoes and the roll out of an effective vaccine being too expensive for many countries, worldwide malaria elimination isn’t a straightforward task.
, of which at least 95 per cent were in Africa, where children under 5 are the most at risk. In 2020, .
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The WHO certifies a country as malaria-free if no cases have been contracted there for at least three years and it shows it has the capacity to react quickly if it starts spreading again.
Azerbaijan and Tajikistan are the two most recent countries to be added to the malaria-free list. They used traditional methods of controlling malaria – such as insecticides, mosquito nets and removing pools of water that the insects use to breed – but they also had relatively few cases to begin with. This makes the parasite easier to eradicate than in many parts of Africa, where it is endemic, says at .
For example, during this century, Azerbaijan’s cases peaked at , compared with Ghana’s in the same year.
at the University of Oxford hopes that a new malaria vaccine that she was involved in developing – called R21 – will help control the parasite in endemic regions.
The WHO is coordinating a programme that delivers the first malaria vaccine – RTS,S – to the most at-risk countries, dropping off doses in Ghana, Kenya and Malawi. and
In contrast, R21, . But Ewer says it is difficult to compare the efficacy of the two vaccines as the trials testing their effectiveness had different designs and they haven’t been analysed in a head-to-head study.
In recent weeks, and became the first countries to approve R21 for children aged between 5 and 36 months. It is yet to be recommended by the WHO, pending further data. The four-dose regimen will cost about $12, says Ewer.
The , the world’s largest vaccine manufacturer, has said it could potentially produce 200 million doses of R21 a year. That would probably meet the global demand “if cost was no issue”, says Ewer.
Unfortunately, that isn’t the case. Global funding for malaria control and elimination was estimated at $3.5 billion in 2021, less than half of the $7.3 billion required annually to achieve the goal of cutting malaria cases and deaths by at least 90 per cent by 2030, . At this rate, global eradication could take decades, says Lasry.
Vaccines aside, climate change will also probably slow these efforts, says Lasry. and this increased lifespan could contribute to rising malaria transmission.
Hotter temperatures may also move malaria-carrying mosquitoes into non-endemic regions, leading to cases among people without immunity, says Lasry.
Extreme weather events, such as flooding, can also hamper interventions. “If you’ve recently launched a bed net campaign and then there’s flooding or a cyclone, you will lose those nets,” says Lasry. These can also lead to stagnant pools of water, increasing mosquito breeding sites, she says.
Insecticide resistance is another worry, says at the Liverpool School of Tropical Medicine, UK. It took about 10 years for mosquitoes to develop resistance to the leading insecticide pyrethroid, with a larger – and more expensive – dose now being required to kill the insects, he says.
For now, there are still effective options, with . “These could last a decade or so before resistance is a massive issue,” says Wondji.
, people in Benin who slept under these nets were 40 per cent less likely to be infected with malaria over the next 18 months compared with those who slept under nets with just pyrethroid.
Insecticides can always be developed, says at the London School of Hygiene and Tropical Medicine. This, along with R21, makes him optimistic that we will see advances towards eliminating malaria. “It’s likely there will be steady progress in the number of countries that achieve malaria elimination in the coming decade,” he says. But funding is a real issue, says Greenwood.
There also isn’t one approach to success. For example, Azerbaijan and Tajikistan partly achieved their malaria-free status by introducing mosquito-eating fish, but these countries have far fewer insect breeding sites than sub-Saharan Africa, where such an approach would be a much bigger task, says Greenwood.
“I don’t think we have or will find a silver bullet,” he says.
