Center for Climate Change and Health Research (CCCHR)

It found that climate change had propelled dengue's spread as temperatures increased.

Climate change caused 19% of dengue infections across the Americas and parts of Southeast Asia, the study found. The infection rates were significantly higher in regions previously thought too cool to support the Aedes  egypti mosquito, which can carry dengue and other diseases.

By 2050, climate change could cause cases to increase by 40% to 57% from today's levels. In cooler urban areas in Bolivia, Peru, Mexico, Brazil and Colombia where the climate is expected to warm temperatures, researchers determined dengue would affect upwards of 257 million people.

“This suggests that we need to be thinking about pandemic preparedness, especially in those parts of the world that are vulnerable to increases in dengue driven by climate change,” said Mallory Jessica Harris, a study co-author who is a postdoctoral researcher at the University of Maryland Institute for Health Computing. “Even in the past few years, we've seen these really large dengue epidemics repeatedly.”

Researchers also shared future projections, based on analyses of 21 countries using an average of 11 years of records for each. The study did not include sub-Saharan Africa or South Asia, two areas also affected by dengue transmission. It also did not include data from the continental U.S.

The study found that temperatures around 82 degrees Fahrenheit are best suited to the mosquitos that can carry dengue. Some regions are projected to warm beyond that range, making it harder for infected mosquitos, or other creatures, to survive. Unfortunately, the research shows that large swaths of the Americas will, instead, reach optimal temperatures in the coming decades. Infections could rise 150 to 200% in previously cooler areas where temperatures are expected to warm to temperatures ideal for dengue transmission.

This includes several cities in the Americas, such as Lima, Peru, which has had unprecedented increases in dengue infections in 2024. This year the U.S. State Department issued a health alert about dengue transmission in Lima. Cases tend to rise during the summer months in the Southern Hemisphere when it is winter in North America.

During warmer winters in the southern region, infected mosquitoes can endure through seasons that typically would kill their populations.

Reference: Childs ML, Lyberger K, Harris M, Burke M, Mordecai EA. Climate warming is expanding dengue burden in the Americas and Asia. MedRxiv. 2024 Jan 9.

 doi: https://doi.org/10.1101/2024.01.08.24301015