Imma Perfetto
Cosmos science journalist
New research has found at least 257 million people now live in places where climate warming could cause dengue incidence to double in the next 25 years in Asia and the Americas
Mild cases of dengue may be asymptomatic or cause fever and flu-like symptoms. Severe cases can cause serious bleeding, a sudden drop in blood pressure (shock), and death. While symptoms can be managed, there is no treatment for the viral infection, but major steps are being taken to reduce the problem.
A study, which was presented last week in New Orleans at the annual meeting of the American Society of Tropical Medicine and Hygiene and is yet to be peer reviewed, found global warming due to climate change is responsible for 19% of the current dengue burden.
Under the IPCC’s high emissions scenario (SSP3-7.0), the researchers expect dengue burden to increase by 61% on average and to more than double in some cooler regions by 2050.
But they estimate that mitigating carbon emissions under the most optimistic emissions scenario (SSP1- 2.6) would reduce this increase in dengue by 18%.
Dr Erin Mordecai, an infectious disease ecologist at Stanford University in the US and senior author of the study, says: “We looked at data on dengue incidence and climate variation across 21 countries in Asia and the Americas and found that there is a clear and direct relationship between rising temperatures and rising infections.”
The team looked at other factors that can affect dengue infection rates, such as rainfall patterns, seasonal changes, virus types, economic shocks and population density, to ensure there was a distinct temperature effect.
“It’s evidence that climate change already has become a significant threat to human health and, for dengue in particular, our data suggests the impact could get much worse,” says Mordecai.
As of October 2024, countries in the Americas alone have recorded almost 12 million dengue cases, compared to 4.6 million in 2023.
The mosquitoes that spread dengue, Aedes aegypti and Aedes albopictus, produce increasing amounts of dengue virus particles from temperatures of about 20°C and peaking at about 28°C.
This means that dengue-endemic areas now entering the temperature range, such as parts of Peru, Mexico, Bolivia and Brazil, could face the greatest future risks, with infections over the next few decades rising by as much as 150% to 200%.
With global climate models predicting that temperatures will continue to increase even with large reductions in emissions, the researchers found that 17 of the 21 countries studied still would see climate-driven increases in dengue even under the most optimistic scenarios for carbon cuts.
