Population at risk of dengue virus transmission has increased due to coupled climate factors and population growth

Dengue virus transmission has increased over the last four decades seemingly due to changes in climate, urbanization and population growth. Using estimates of dengue transmission suitability based on historical temperature and humidity data, we examined how shifts in these climatic variables and human population growth have contributed to the change in the geographical distribution and size of the global population living in areas with high climate suitability from 1979 to 2022. We found an expansion in climate suitability in North America, East Asia and the Mediterranean basin, where with few exceptions, endemicity is not yet established. Globally, we estimated that the population in areas with high climate suitability has grown by approximately 2.5 billion. In the Global South, this increase was largely driven by population growth in areas with historically favorable climate suitability, while in the Global North this increase predominantly occurred in previously unfavorable areas with limited population growth. Changes in population growth and climatic conditions have increased the risk for dengue transmission, particularly in the Global South, according to a virus transmission index applied to 186 countries from 1979 to 2022.