A 2025 study reveals that global warming is already causing millions of dengue infections annually, with cases expected to rise sharply
Rising global temperatures are already reshaping the landscape of infectious diseases. A 2025 study by Stanford University demonstrates that climate change has contributed to an estimated 4.6 million additional dengue fever cases annually, with projections indicating a potential increase of up to 76% by 2050.
The research, covering 21 countries across Latin America and Southeast Asia, highlights how warming trends expand the geographic and seasonal range of dengue, particularly in cooler tropical and subtropical regions.
The analysis, published in PNAS, is the most comprehensive estimate of how temperature shifts affect the spread of dengue fever.
Dengue fever is spreading rapidly
Dengue fever, a mosquito-borne disease once mainly confined to the tropics, is now spreading across continents. It brings flu-like symptoms and can develop into severe bleeding, organ failure and death if left untreated. The Aedes aegypti and Aedes albopictus mosquitoes, which thrive in warm and humid environments, are the primary vectors for dengue fever, making it a disease particularly sensitive to climate change.
New figures from researchers at Stanford, Harvard, Arizona State University, and the National Bureau of Economic Research have found that dengue fever cases could increase by 76% across Asia and the Americas by 2050. This research provides the first direct evidence that global warming has already increased the disease’s impact.
“The effects of temperature were much larger than I expected,” said lead author Marissa Childs, an assistant professor of environmental health at the University of Washington who did most of the research as a PhD student in Stanford’s Emmett Interdisciplinary Program in Environment and Resources and then as a postdoctoral fellow at the Harvard University Center for the Environment and the Harvard T.H. Chan School of Public Health. “Even small shifts in temperature can have a big impact on dengue transmission, and we’re already seeing the fingerprint of climate warming.”
Millions of dengue cases attributable to climate change
The study analysed over 1.4 million observations of local dengue fever incidence across 21 countries in Central and South America, as well as Southeast and South Asia, capturing data on epidemic spikes and infection levels.
Dengue fever thrives in temperatures of approximately 27.8°C, rising sharply as cooler regions warm but dropping slightly when already hot areas exceed the optimal range. As a result, some of the increases are projected for cooler, high-population areas in countries such as Mexico, Peru, and Brazil. Many other endemic regions will continue to experience larger, warming-fueled dengue burdens. By contrast, a few of the hottest lowland areas may see slight declines. Still, the net global effect is a steep rise in disease.
The findings suggest that higher temperatures from climate change were responsible for an average of 18% of dengue incidence across 21 countries in Asia and the Americas from 1995 to 2014, translating to more than 4.6 million extra infections annually, based on current incidence estimates. Dengue fever cases could increase from 49% to 76% by 2050, depending on the levels of greenhouse gas emissions.
“Many studies have linked temperature and dengue transmission,” said study senior author Erin Mordecai, a professor of biology in the Stanford School of Humanities and Sciences. “What’s unique about this work is that we can separate warming from all the other factors that influence dengue—mobility, land use change, population dynamics—to estimate its effect on the real-world dengue burden. This is not just a hypothetical future change but a large amount of human suffering that has already happened because of warming-driven dengue transmission.”
The actual impact may be significantly greater than predicted
The researchers warn that their estimates are likely conservative and do not account for regions where dengue transmission is poorly reported, nor do they include large endemic areas such as India and Africa, where detailed data are lacking.
The researchers also emphasise that recent locally acquired cases in California, Texas, Hawaii, Florida and in Europe are a cause for concern, signalling the expansive reach of the disease.
Aggressive climate mitigation would significantly decrease the burden of dengue fever. Better mosquito control, stronger health systems, and the widespread use of new dengue vaccines would also help.
“Climate change is not just affecting the weather—it has cascading consequences for human health, including fueling disease transmission by mosquitoes,” Mordecai said. “Even as the U.S. federal government moves away from investing in climate mitigation and climate and health research, this work is more crucial than ever for anticipating and mitigating the human suffering caused by fossil fuel emissions.”