Climate change redraws Africa’s malaria map, East Africa hardest hit

Malaria transmission has risen sharply in East and Southern Africa as climate change warms areas once considered too cool for the disease, a major study has found.

Climate change has increased malaria transmission by 84 per cent in East Africa and 91 per cent in Southern Africa, according to research published in Nature.

The study offers some of the clearest evidence yet that rising temperatures are changing where malaria can spread across the continent.

Researchers found that parts of East Africa, including highland areas, are becoming increasingly suitable for malaria transmission as temperatures rise.

But in parts of West and Central Africa, where temperatures are already high, further warming may make conditions less favourable for malaria mosquitoes and the parasites they carry.

Dr Colin Carlson, an associate professor at Yale University, led the study that analysed more than 50,000 malaria surveys collected across sub-Saharan Africa over the past century and compared them with historical climate records.

They also accounted for factors such as mosquito nets, indoor spraying, access to treatment, health systems, poverty, conflict and drug resistance, enabling them to estimate the specific contribution of human-caused climate change to malaria transmission.

Malaria mosquitoes and the parasites they carry thrive at around 25°C. At lower temperatures, the parasite develops too slowly inside mosquitoes to spread effectively. At very high temperatures, mosquitoes and parasites also struggle to survive, creating a climate divide across Africa.

In East Africa, warming is making some previously cool highland areas more suitable for malaria. Communities that historically faced relatively low risk could therefore become more vulnerable.

In parts of West and Central Africa, further warming may push temperatures beyond the malaria parasite’s preferred range, slightly reducing transmission in some locations.

The researchers stressed, however, that these regions remain heavily affected by malaria because other factors continue to drive transmission.

READ ALSO: Climate change now direct threat to Nigeria’s economy and security — Experts

Despite the regional changes, the study found that climate change has so far had a much smaller effect on malaria than public health interventions.

Across sub-Saharan Africa, climate change has resulted in an average of about one additional malaria case per 1,000 children since 1900.

Meanwhile, measures including insecticide-treated bed nets, indoor spraying, rapid diagnostic tests, improved medicines and stronger surveillance have reduced malaria prevalence by about 16 percentage points.

The researchers said climate change is therefore shifting malaria risk rather than increasing it everywhere.

Public health measures have prevented far more infections than climate change has caused so far. But continued warming could make changing disease patterns increasingly difficult to manage.

Researchers also warned about Anopheles stephensi, an invasive mosquito species that can tolerate hotter temperatures and thrive in urban environments.

The mosquito has already spread across parts of East Africa and could increase malaria transmission in African cities if it becomes more widespread.

The researchers urged governments to strengthen malaria surveillance, particularly in high-altitude areas that have historically experienced little transmission.

They also called for continued investment in mosquito nets, indoor spraying, effective medicines, rapid diagnosis and community health programmes.

The study’s warning is straightforward: climate change may not yet be Africa’s biggest malaria driver, but it is steadily changing the disease’s map.

As temperatures rise, communities that have historically been protected by cooler climates could increasingly find themselves at risk.