Climate change and malaria
The World Health Organization calls climate change the single biggest threat facing humanity.1 The Intergovernmental Panel on Climate Change has warned of the need to limit the rise in global temperatures to 1.5°C above the baseline. Meanwhile, climate change is already placing marginalized populations at greater risk of economic hardship, malnutrition and diseases like malaria.
Malaria is endemic in low-resource settings, and these are also the region's most heavily impacted by climate-related disasters. Climate change is a threat multiplier: it makes escaping poverty and accessing healthcare harder and widens existing inequality gaps, for example for women and children. It is also highly unpredictable, and extreme weather events like floods, heatwaves and droughts are disproportionately affecting the world’s least developed countries. The climate crisis threatens to undo the progress already made in saving lives and controlling malaria in endemic countries, while introducing new challenges that could slow future progress.
Examples of these new challenges include:
Higher temperatures, increased rainfall and humidity are increasing the geographic range of mosquito vectors, which are moving outwards from the equator and to higher altitudes in Africa, where the population and health infrastructure are unprepared for malaria outbreaks.
The length of rainy seasons is being extended, prolonging the annual timeframe in which malaria is transmitted in sub-Saharan Africa. Conversely, extended hot/dry spells can cause bodies of water like rivers, lakes and streams to dry up into small stagnant pools, creating breeding grounds for malaria-causing mosquitoes.
Malaria vectors like An. Stephensi, which is native to southern and western Asia, are being identified in new geographies, like Sudan. (There is some evidence to suggest that the behavior of the species is closely linked to rising temperatures, and further studies are ongoing).
Climate change and unpredictability
Measuring and predicting the impact of climate change on malaria, both now and in the future, is a complex task. A WHO study on the ‘Quantitative risk assessment of the effects of climate change on selected causes of death, 2030s and 2050s’ estimates that climate change will cause 60,000 additional malaria deaths annually in this timeframe. The assessment uses annual temperature and precipitation data to develop its research model, but other factors are also at play – factors that are not always easy to quantify.
Though difficult to predict, the impacts of climate change on malaria are already evident. For instance, the 2022 flood in Pakistan led to a considerable uptick in malaria cases due to the stagnant bodies of water left over once the heavy rain subsided, and the damage done to the country’s infrastructure made healthcare inaccessible for millions of people, especially those in remote areas. Similarly, the cyclones that have hit Mozambique in recent years have also caused surges in malaria cases – stagnant bodies of water have become mosquito breeding sites, the destruction of healthcare infrastructure has made access to treatment harder and hundreds of thousands of people have been left homeless, making them more susceptible to malaria transmission. The most at-risk people and communities in both countries have been hit the hardest by these extreme weather events.
A global response to new challenges
With unpredictability comes the pressing need to protect and support the people most affected by the impacts of climate change, while building resilience in countries and across healthcare systems to mitigate the short and medium-term impacts of climate change. Moreover, the global community needs to continue developing new operational models aligned with the longer-term global net-zero ambition outlined in the Paris Agreement, the international treaty on climate change adopted by 196 parties at the UN Climate Change Conference (COP21) in Paris, France in 2015.
For malaria, addressing these needs means investing in R&D to further expand the toolbox of medicines used to prevent and treat the disease, and adapting prevention programmes to best respond to changes in seasons and temperatures. Developing local manufacturing capabilities, strengthening supply chains in malaria endemic countries and ensuring healthcare infrastructures are more resilient to the extreme weather events associated with climate change are also priorities.
Though we can't predict when the next climate disaster will occur and how it will affect the most vulnerable among us, what we do know is that climate change will continue to impact our collective ability to respond to malaria and other diseases of poverty. Building resilience against this unpredictability requires global action.