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Changing weather is projected to increase malaria cases and deaths in Africa. Between 2030 and 2049, an estimated 554,000 additional malaria deaths in Africa will be due to climate-related impacts, mainly driven by extreme weather events. These events are expected to account for 92 percent of the excess deaths.
In a published interview, the World Health Organization warns, “Climate change is not good for malaria. Rising temperatures, shifting rainfall patterns and more frequent extreme weather events are already expanding malaria zones and seasons, while disrupting health systems in Africa.”
Although current malaria control tools can reduce the overall toll, their effectiveness may drop by up to 17 percent due to climate effects. By mid-century, 75 percent of sub-Saharan Africa’s population,1.3 billion people, will live in areas where eradication becomes more difficult.
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First published on the WHO website
Global incidence and mortality rates have stabilized since the COVID-19 pandemic, but cases and deaths remain higher than in 2019, before the pandemic. What explains this?
It’s worth noting that, even before the pandemic, the global trends in malaria cases and deaths had flattened and, in many countries, progress had stopped. The pandemic emerged against this background. At the beginning of the pandemic, WHO convened a multi-partner working group. Among other things, the group conducted a modelling exercise that predicted that if countries did not respond swiftly and effectively, the pandemic would set us back to 2000 levels of malaria burden. Thankfully, countries, with the support of WHO and partners, launched an impressive exercise to maintain essential malaria services. Despite an initial rise in cases in 2020, these efforts managed to largely prevent a further worsening of the trend in 2021 and 2022.
There were many reasons for the stalled progress prior to the pandemic. The common thread across many countries was that of constrained resources and difficulties in reaching the required level of interventions, particularly in poor, rural areas. Extreme weather events posed an additional challenge in some hard-hit countries. In other countries, the funding response was inadequate to meet the needs of a rapidly increasing population at risk of malaria. Additional factors included the chronic challenges of health systems to provide prompt, high-quality services; the impacts of other humanitarian disasters, including those caused by conflict; and rising biological threats to malaria control –particularly mosquito resistance to the insecticides which are necessary to protect the efficacy of the two main interventions in malaria vector control: insecticide treated nets (ITNs) and indoor residual spraying (IRS).
The impact of these factors varies widely among countries. Nonetheless, weak monitoring and health information systems in many countries with a moderate-to-high malaria burden obstruct more detailed subnational analyses. Enhancing our responses to malaria globally and locally hinges on establishing robust surveillance systems that can identify and interpret emerging challenges.
How has climate change affected malaria transmission?
Malaria is a disease that is driven by the environment. It is sensitive to climatic indicators of temperature, rainfall, and humidity. Climate change is affecting global environmental temperatures which, in turn, affect patterns of rain and humidity, as well as the magnitude and frequency of extreme weather events. So, climate change is a significant concern for the global malaria response.
Evidence on the direct effects of climate change on long term malaria trends in transmission is sparse and mixed. Areas now on the margins of transmission may become more or less suitable to mosquito survival and breeding. Malaria may be introduced in cooler areas as they warm. Some of the strongest available data are from the African highlands, where rising temperatures have contributed to the establishment of malaria in areas that were previously malaria-free. The epidemic experienced by Pakistan as a result of the extreme monsoon rains is another example, as there is evidence to suggest that the severity of the monsoon season was heightened by climate change.
On the other hand, climate change that increases aridity and dryness could impair mosquitos’ ability to breed and survive, eliminating malaria from some areas that are currently malaria endemic. Climate change may also make malaria seasons longer, thereby increasing burden or reducing the predictability of seasons, affecting the accurate timing of seasonal malaria interventions.
Indirect impacts of climate change can also greatly influence malaria burden. These include large-scale population displacement, disruptions of health systems, infrastructure, food security, livelihoods and economies. The fiscal strain of addressing these multiple challenges can impair the ability to sustain malaria programmes.
How has climate change affected the delivery of malaria services? What impact, if any, has this had on incidence and mortality rates?
It is empirically very difficult to attribute a specific effect on malaria transmission directly to climate change. However, as per the Intergovernmental Panel on Climate Change (IPCC), we know that climate change has increased the frequency and intensity of extreme weather events, and that such events can lead to malaria epidemics.
For instance, although it’s unclear to what degree the devastating floods in Pakistan in 2022 can be attributed to climate change, evidence suggests it heightened the severity of the monsoon season. It is also evident that a malaria outbreak ensued, with the rate of transmission surging five-fold, with 2.1 million additional cases in 2022 over 2021. The floods damaged 1000 health facilities in the country, leaving millions of people without access to health care in affected districts, and driving up the number of deaths from malaria.
What are the most significant risks posed by climate change for malaria control and prevention?
All the risks mentioned above must be considered in malaria programme planning. At the same time, the impacts of climate change on malaria will vary across diverse economic, social and ecological contexts. In some settings, indirect effects may be more important than direct effects.
The key point is that any factor, including climate change, which negatively impacts community well-being will consequently have detrimental effects on malaria outcomes. We must think about how to respond proactively to climate change and its impacts on health, and how to nest the malaria response synergistically within the broad health and climate change response.
WHO has said that climate change is the single greatest threat to global health. Does this hold true for malaria?
Overall, climate change is not good for malaria. Projections show that, without a significant investment in reducing greenhouse gases and in climate change adaptation, there will be considerable adverse health consequences. At the same time, there will be a need for significantly greater investment in malaria control, above and beyond current levels.
A worst-case climate scenario without considerable scale up of malaria interventions would see an increase in malaria cases. However, if investments are considerably scaled and coverage gaps are closed, particularly in rural areas, and the promising pipeline of malaria products come to communities, then we are likely to make significant progress in malaria and curb the threat of climate change.
This is not an issue of investing in one or the other. Getting rid of malaria will increase communities’ resilience to climate change. Climate change mitigation and adaptation will give the malaria response a greater chance to succeed.
How can country programmes and the global malaria community address these threats?
First, we need to close the funding gap for malaria. The gap between the amount invested in malaria control and elimination and the resources needed is dangerously large, growing from US$ 2.3 billion in 2018 to US$ 3.7 billion in 2022. Total spending in 2022 reached US$ 4.1 billion – well below the US$ 7.8 billion required globally to stay on track for the global milestones of reducing case incidence and mortality rates by at least 90% by 2030 (compared with a 2015 baseline).
Funding is crucial for scaling up core interventions to control and eliminate malaria – such as insecticide-treated nets, vaccines, and preventive therapies for infants, children and pregnant women, as well as diagnosis and treatment. Investment is also needed to develop climate resilient tools and interventions. Increased funding is needed to improve surveillance, data collection and analysis, and to address the biological threats to malaria control.
Equally crucial is the need to position the fight against malaria within the climate change/health nexus, and to equip communities to anticipate, adapt to and mitigate the effects of climate change, including the rise of extreme weather events. As you will see in the report, there are a range of actions –strategic, technical and operational – that countries and their partners should begin to pursue now.
What is the role of data in addressing these threats and eliminating malaria?
First and foremost, malaria is one of the world’s biggest public health problems and there are several cornerstones of public health. One of these is the use of surveillance and data at the local level to respond to public health priorities.
Malaria is highly heterogenous over short periods of time and short distances, and it is influenced by many social and economic determinants of health, as well as by malaria interventions. This complex, dynamic system requires that we collect the right data and use it for the right purposes.
Despite significant improvement over the last few years, countries and their global partners have underinvested in surveillance. There has also been a certain level of inertia in ensuring that country-level analysis of sub-national data adequately informs investments.
Addressing the growing threat of climate change will require broader investments in health and meteorological data, too. Such investments would help malaria-endemic countries detect, prepare for, respond to, and recover from short-term climate related shocks.
WHO has been at the forefront in supporting countries in sub-national tailoring of malaria interventions and will soon be issuing guidance on prioritization of those interventions to optimize impact.
With the vast majority of gains made since 2000 still intact, why should we be concerned now about malaria, and how concerned should we be?
About US$ 50 billion has been invested in the malaria response since 2000. While we are better off in terms of case incidence (cases per 1000 people at risk) than we were in 2000, having reduced it by 28%, and more countries than ever are approaching elimination, we are nonetheless faced by the same number of cases today as we had in 2000. This is due to the environmental, climatic and biological threats to malaria control as well as the challenges of reaching an ever-increasing population at risk.
Despite the progress made, the burden of malaria is still unacceptably high. Any notion of sustaining gains without the intent of making further progress will only lead to a resurgence of malaria.
There is every reason to continue to scale up investments in malaria. To date, those investments have averted nearly 12 million deaths and more than 2 billion cases of disease and represent one of the biggest, if not the biggest, return on investment in global health in recent times.