19% of rising dengue cases due to climate change: Study

Amid record year for dengue infections globally, a new study has found that climate change is responsible for 19 per cent of rising dengue burden.

Climate change has the potential to spark an additional 40-60 per cent spike by 2050 — and by as much as 150-200 per cdent in some areas — according to a new study presented at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in the US.

India has also seen a surge in dengue cases this year. The latest findings from researchers at Stanford and Harvard Universities offer the most definitive evidence to date that climate change is a big factor driving a global surge in the mosquito-borne disease.

Countries in the Americas alone have recorded almost 12 million cases in 2024 compared to 4.6 million in 2023, and locally acquired infections have been reported in California and Florida. The study also carries warnings of even sharper increases to come.

“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,” said Erin Mordecai, an infectious disease ecologist at Stanford’s Woods Institute for the Environment. 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, Mordecai added.

While some dengue infections produce only mild symptoms, others cause excruciating joint pain (earning dengue the nickname “breakbone fever”), and severe cases can lead to bleeding complications and shock. There are no drugs to treat the disease and while there are two licensed dengue vaccines available, some dengue experts have pointed to challenges with both that could limit widespread adoption.

The study finds that amid dengue’s growing threat, moderating global warming by reducing emissions would also moderate climate impacts on dengue infections. The analysis shows that with sharp cuts in emissions, areas now on track to experience a 60 per cent increase would instead see about a 40 per cent rise in dengue infections between now and 2050.

However, 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.

Mordecai said dengue-endemic areas that are just entering the 20 to 29 degree C sweet-spot for virus transmission — parts of Peru, Mexico, Bolivia and Brazil — could face the biggest future risks, with infections over the next few decades rising 150 to 200%.