How climate change affects mosquito-borne infectious disease: The different trajectories of malaria and dengue

As climate change increases temperatures, additional warmth combines with rainfall and humidity to enhance conditions for mosquito populations to thrive. Greater spread of Anopheles and Aedes vectors increases the risk of transmission of the world’s most prevalent mosquito-borne infectious diseases, malaria and dengue. Yet the impacts of climate drivers on disease transmission are complex: Relationships are nonlinear, effects are seasonal, and there is substantial local variability. Further complexity is added by the many nonclimate factors that influence disease transmission, including movement of people, population growth, immunity levels, land use change, urbanization, control interventions, and quality of health care systems. Here, we explain why, despite climate drivers having broadly similar effects on malaria and dengue transmission parameters, the trajectories of the two diseases differ, with rapid growth in dengue but long-term decline in malaria.