September 12, 2025
A worker conducts anti-mosquito fogging in Bali, Indonesia. Credit: Pepszi/Getty Images
Warmer weather across the globe is reshaping the landscape of human health. Case in point: Dengue fever incidence could rise as much as 76% by 2050 due to climate warming across a large swath of Asia and the Americas, according to a new study led by Marissa Childs, a researcher at the University of Washington.
Dengue fever, a mosquito-borne disease once confined largely to the tropics, often brings flu-like symptoms. Without proper medical care, it can escalate to severe bleeding, organ failure, and even death.
The study, published Sept. 9 in PNAS, is the most comprehensive estimate yet of how temperature shifts affect dengue’s spread. It provides the first direct evidence that a warming climate has already increased the disease’s toll.
“The effects of temperature were much larger than I expected,” said Childs, a UW assistant professor of environmental health who conducted much of the research as a doctoral student at Stanford University. “Even small shifts in temperature can have a big impact for dengue transmission, and we’re already seeing the fingerprint of climate warming.”
The study analyzed over 1.4 million observations of local dengue incidence across 21 countries in Central and South America and Southeast and South Asia, capturing both epidemic spikes and background levels of infection.
Dengue thrives in a “Goldilocks zone” of temperatures – incidence peaks at about 27.8 degrees Celsius, or 82 degrees Fahrenheit, rising sharply as cooler regions warm but dropping slightly when already-hot areas exceed the optimal range. As a result, some of the largest increases are projected for cooler, high-population regions 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 18% increase 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. Cases could climb another 49% to 76% by 2050 depending on greenhouse gas emissions levels, according to the study. At the higher end of the projections, incidence of dengue would more than double in many cooler locations, including areas in the study countries that are already home to over 260 million people.
“Many studies have linked temperature and dengue transmission,” said 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 are able to 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 hypothetical future change but a large amount of human suffering that has already happened because of warming-driven dengue transmission.”
The researchers cautioned that their estimates are likely conservative. They do not account for regions where dengue transmission is sporadic or poorly reported, nor do they include large endemic areas such as India or Africa where detailed data is lacking or not publicly available. The researchers also highlighted recent locally acquired cases in California, Texas, Hawaii, Florida, and in Europe — a signal of the expanding range of dengue. Urbanization, human migration and the evolution of the virus could amplify risks, while medical advances may help blunt them, making projections uncertain.
Aggressive climate mitigation would significantly reduce the dengue disease burden, according to the study. At the same time, adaptation will be essential. This includes better mosquito control, stronger health systems and potential widespread use of new dengue vaccines.
In the meantime, the findings could help guide public health planning and strengthen efforts to hold governments and fossil fuel companies accountable for climate change damages. Attribution studies are increasingly entering courtrooms and policy debates, used to assign responsibility for climate damages and to support funds compensating countries most affected.
“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.”
Co-authors of the study include Kelsey Lyberger of Arizona State University, Mallory Harris of the University of Maryland, and Marshall Burke of Stanford. Lyberger and Harris completed much of their work while at Stanford.
The research was funded by the Illich-Sadowsky Fellowship through the Interdisciplinary Graduate Fellowship program at Stanford University; an Environmental Fellowship at the Harvard University Center for the Environment; the National Institutes of Health; the National Science Foundation (with the Fogarty International Center); the Stanford Center for Innovation in Global Health; the Stanford King Center on Global Development; and the Stanford Woods Institute for the Environment.
Adapted from a press release by Stanford University. For more information or to contact the researchers, email Alden Woods at acwoods@uw.edu.
Tag(s): climate change • Department of Environmental & Occupational Health Sciences • infectious disease • Marissa Childs • School of Public Health