A new model for predicting the effects of climate change on malaria transmission in Africa could lead to more targeted interventions to control the disease according to a new study. It has also highlighted the role of waterways such as the Zambezi River in the spread of the disease with almost four times the population estimated to live in areas suitable for malaria for up to nine months of the year than was previously thought. Malaria is a climate-sensitive vector-borne disease that caused 608,000 deaths among 249 million cases in 2022. 95% of global cases are reported in Africa but reductions in cases there have slowed or even reversed in recent years, attributed in part to a stall in investments in global responses to malaria control.

The researchers predict that the hot and dry conditions brought about by climate change will lead to an overall decrease in areas suitable for malaria transmission from 2025 onwards. The new hydrology-driven approach also shows that changes in malaria suitability are seen in different places and are more sensitive to future greenhouse gas emissions than previously thought. The key advancement is that these models factor in that not all water stays where it rains, and this means breeding conditions suitable for malaria mosquitoes too can be more widespread -- especially along major river floodplains in the arid, savannah regions typical of many regions in Africa. What is surprising in the new modelling is the sensitivity of season length to climate change -- this can have dramatic effects on the amount of disease transmitted.

Although an overall reduction in future risk of malaria might sound like good news, it comes at a cost of reduced water availability and a greater risk of another significant disease, dengue. The researchers hope that further advances in their modelling will allow for even finer details of waterbody dynamics which could help to inform national malaria control strategies. They're getting to the point soon where they use globally available data to not only say where the possible habitats are, but also which species of mosquitoes are likely to breed where, and that would allow people to really target their interventions against these insects.