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Rainfall, temperature and vegetation greenness are key but nonlinear, delayed drivers of malaria across 20 Sub-Saharan African nations.
The findings were published in a multi-country study that linked 2,400 monthly observations of malaria incidence with climate, population density and elevation.
Moderate rain, optimal temperatures and greener landscapes were found to boost mosquito survival and transmission risk.
A new study published in the journal Nature Scientific Reports found that rainfall, temperature and vegetation significantly influence malaria transmission across Sub-Saharan Africa.
These climatic influences are not straightforward; their effects are both nonlinear and delayed, meaning that changes in weather conditions may affect malaria risk weeks or even months later, the findings showed.
The researchers underlined the importance of integrating climate information into malaria surveillance and early warning systems.
They analysed monthly malaria data from 20 countries in West, East, Central and Southern Africa between January 2015 and December 2024. The countries included Benin, Botswana, Burkina Faso, Cameroon, Ethiopia, Ghana, Kenya, Liberia, Malawi, Mali, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Tanzania, Uganda and Zambia.
The focus was sub-Saharan Africa because the region carries the vast majority of the world’s malaria burden. According to the World Health Organization, an estimated 282 million malaria cases and 610,000 malaria deaths occurred globally in 2024. About 95 per cent of both malaria cases (265 million) and deaths (579,000) were reported from the WHO African Region, where children under five accounted for about 75 per cent of malaria deaths.
The analysts examined 2,400 monthly observations, making the study one of the largest multi-country assessments of climate-sensitive malaria transmission conducted in the region.
Monthly malaria incidence per 1,000 people was noted in relation to rainfall, near-surface air temperature and vegetation greenness. In addition to climatic variables, the researchers included population density and elevation to account for demographic and geographical influences on disease transmission.
The findings showed malaria does not increase or decrease uniformly with climatic changes. Moderate rainfall creates favourable breeding conditions for mosquitoes, whereas excessive rainfall can wash away larvae and reduce transmission.
Similarly, temperatures within an optimal range accelerate mosquito growth and parasite development, but extremely high temperatures become less favourable for transmission.
Vegetation also remained a strong predictor of malaria because it reflects moisture and habitat conditions that support mosquito survival.
According to the study, population density was positively associated with malaria incidence, suggesting that densely populated areas increase opportunities for mosquito-human contact. In contrast, higher altitudes showed lower malaria risk because cooler temperatures restrict mosquito development.
The scientists also identified important delayed climate effects. Changes in rainfall and temperature influenced malaria incidence several weeks or months later, reflecting the time required for mosquito breeding and parasite development.
The study concluded that integrating climate data into malaria early warning systems could help health authorities better target interventions such as insecticide-treated net distribution, indoor spraying and case management, particularly in vulnerable lowland communities facing increasing climate-related risks.
