Warming temperatures reduce lifespan and vectorial capacity of Anopheles mosquitoes in Ghana.

Climate change and variability are altering the ecology of malaria vectors, with implications for disease transmission in sub-Saharan Africa. In this study, we analysed long-term historical temperature, rainfall and relative humidity data across Ghana's climatic zones to evaluate their trends. We then incorporated these data into simple climate-driven biological models to assess how they impacted Anopheles mosquito lifespan, their Vectorial Capacity and Extrinsic Incubation Period of malaria parasites. This approach allowed us to assess the potential impacts of climate change on malaria transmission dynamics in the country. The analysis revealed, on the long-term, significant temperature warming (over 1.5°C), marked decline in relative humidity, and no clear trends in rainfall across all climatic zones. Similarly, Anopheles mosquito lifespan (with seasonal variations of 5-11 days in the north and 9-14 days in the south) showed long-term decline while Extrinsic Incubation Period (with seasonal average range of 6-11 days in the north and up to 13 days in the south) showed shortened development time. Even though Vectorial Capacity showed no clear long-term trends, its values were generally below 10, indicating low-to-moderate malaria transmission potential nationwide. Although regional and local microclimatic variations may continue to support localized malaria transmission risk, the long-term rise in temperatures and decline in humidity are likely reducing mosquito longevity and malaria transmission potential in Ghana. These findings underscore the importance of climate-informed and region-specific strategies in the National Malaria Elimination Program to improve targeted interventions and optimize vector control efforts.