Dengue fever spiked to record levels in 2024: Climate change will make it even worse
published 17 November 2024
Dengue fever, a potentially fatal virus spread by mosquitoes, is sweeping across the Americas, breaking records with a skyrocketing rate of infections.
Cases have spiked in large part due to increasing global temperatures wrought by greenhouse gas emissions, new research shows.
Nearly a fifth of dengue infections in the Americas and Southeast Asia were propelled by climate change, according to a study that researchers from the University of Maryland, Harvard University and Stanford University presented Saturday at the annual American Society for Tropical Medicine and Hygiene meeting in New Orleans.
The latest data from the Pan-American Health Organization shows that in the first 10-plus months of 2024, there were nearly 7,500 deaths and more than 12.3 million infections – three times the number of cases in 2023, which was record-setting at the time.
“Dengue is really having its biggest year in history,” said Dr. Gabriela Paz-Bailey, chief of the U.S. Centers for Disease Control and Prevention’s dengue branch, based in Puerto Rico. “Around the world, dengue cases have been rising at an alarming rate.”
The sharp uptick has caused concern in the U.S., especially in Puerto Rico, where officials estimate up to 50% of infections have resulted in hospitalization, Paz-Bailey said. The U.S. has recorded nearly 7,300 infections this year, compared to 1,462 in 2023. Most of these cases were in Puerto Rico, which declared a public health emergency this spring and has remained under emergency status.
The continental U.S. hasn’t had a high rate of infections compared with the early 2010s. But officials worry about projections in a warming climate.
Most people who get dengue don't show symptoms, but those who do sometimes develop a high fever, body aches, nausea and rashes. Some infections result in hospitalization or death.
In severe cases – usually about 1 in 20 infected individuals, people bleed internally or from their nose or mouth and go into shock. Infants, elderly people and pregnant women are most at risk for serious forms of disease.
There are four dengue viruses. A person infected with one of them could have limited immunity to some of these viruses. Populations are sometimes exposed to various strains, reigniting outbreaks. Repeated infections can trigger severe dengue.
Climate change already responsible for record dengue increases
The new study by Maryland, Harvard and Stanford didn't include the benchmark 2024 spike. But 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.”