Climate Change Is Shifting Malaria Risk, Pakistan’s Flood Experience Raises Alarm

Climate change is reshaping the global pattern of malaria, with scientists warning that warming could make some cooler regions more suitable for transmission while extreme weather may trigger much larger outbreaks.

Malaria transmission is highly sensitive to temperature. Research has shown that transmission of Plasmodium falciparum, one of the most dangerous malaria parasites, is most favourable at around 25°C. This means warming can increase malaria risk in places where temperatures have historically been too cool, while areas that become extremely hot may eventually become less suitable for transmission.

A major study published in Nature shows how uneven those changes could be across Africa.

Researchers project that warming could increase malaria risk in parts of Southern Africa, including Angola and Zambia, as well as highland areas of Ethiopia, Kenya, Rwanda, Burundi and the eastern Democratic Republic of Congo, where cooler temperatures currently limit transmission.

In parts of the Sahel, however, rising temperatures could reduce ecological suitability as conditions move beyond the optimal range for malaria-carrying mosquitoes.

Extreme weather may be the bigger threat

Temperature alone may not be the greatest climate-related danger.

The Nature study estimates that, under a medium climate-change scenario and if current malaria-control levels remain unchanged, climate change could contribute to around 123 million additional malaria cases and 532,000 additional deaths across Africa between 2024 and 2050.

Researchers estimate that extreme weather and the disruption it causes could account for around 79% of the additional cases and 93% of the additional deaths.

The reason goes beyond changes in mosquito habitat.

Floods and other disasters can damage homes and health facilities, reduce access to malaria testing and treatment, and interrupt mosquito-control programmes. At the same time, standing water left behind by flooding can create additional breeding sites for mosquitoes.

This means the health impact of climate change may depend as much on the resilience of health systems and communities as on changes in temperature itself.

Pakistan offers a clear warning

Pakistan’s experience following the catastrophic 2022 floods offers a striking example of how an extreme-weather disaster can intensify an existing disease threat.

According to the World Health Organization, more than 3.4 million suspected malaria cases were reported in Pakistan between January and August 2022, compared with 2.6 million during the whole of 2021.

A rapid increase in cases followed the floods, particularly in Sindh and Balochistan.

WHO reported that confirmed malaria cases in Sindh reached 69,123 in August 2022, compared with 19,826 in August 2021. Balochistan reported 41,368 confirmed cases in August 2022, up from 22,032 during the same month a year earlier.

Together, Sindh and Balochistan accounted for 78% of Pakistan’s confirmed malaria cases reported at the time.

The Global Fund later reported more than 1.6 million confirmed malaria cases across 60 districts in 2022, around four times the roughly 400,000 cases recorded the previous year.

Floodwater provided conditions in which mosquitoes could breed, while damaged health infrastructure and the displacement of millions of people made prevention, diagnosis and treatment more difficult.

Climate change will not affect every region equally

Scientists caution against assuming that global warming will simply increase malaria everywhere.

The relationship between climate and malaria is more complicated.

Temperature, rainfall and humidity influence whether mosquitoes can survive and whether malaria parasites can develop inside them. But the final disease burden also depends on existing levels of transmission, housing conditions, access to treatment, mosquito-control programmes and the ability of health systems to function during emergencies.

The Nature research suggests that some areas could become less climatically suitable for malaria even as others experience increasing risk.

But extreme weather complicates that picture. In some places where warming may reduce ecological suitability for malaria, floods and disruption to health services could still push disease risk higher.

That distinction matters for countries already vulnerable to both malaria and climate-related disasters.

Pakistan’s post-flood experience shows how quickly an existing public-health problem can escalate when extreme weather creates favourable conditions for disease while simultaneously weakening the systems needed to control it.

The emerging evidence suggests that preparing for future malaria risk will require more than tracking temperature changes. Climate-resilient health facilities, reliable access to treatment, mosquito control and stronger emergency-response systems may become increasingly important as extreme weather intensifies.