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 changing how infectious diseases spread. A 2025 study by Stanford University shows that climate change has led to about 4.6 million more dengue fever cases each year. Experts expect this number could increase by up to 76% by 2050.

The study looked at 21 countries in Latin America and Southeast Asia. It found that as temperatures warm, dengue fever is spreading to new areas and lasting for longer periods, especially in cooler tropical and subtropical regions.

The research, published in PNAS, is the most detailed estimate of how temperature changes affect the spread of dengue fever.

Dengue fever is spreading rapidly

Dengue fever is a mosquito-borne disease that was once mostly found in the tropics.Now,it’s spreading to more continents. It causes flu-like symptoms and can become severe, leading to bleeding, organ failure, and even death if not treated. The Aedes aegypti and Aedes albopictus mosquitoes, which like warm and humid places, spread dengue fever. This makes it a disease very sensitive to climate change.

New data from researchers at Stanford, Harvard, Arizona State University, and the National bureau of Economic Research suggests that dengue fever cases could increase by 76% in Asia and the Americas by 2050. This research is the first direct proof that global warming is already making the disease worse.

“The effects of temperature were much larger than I expected,” said Marissa Childs, the lead author and an assistant professor of environmental health at the University of Washington. She did most of the research while getting her PhD at Stanford’s Environmental and Policy Institute.