Climate Change Linked to 20% of Dengue Fever Cases: Study Shows Alarming Impact

A new study suggests that nearly 20% of cases of dengue fever, a mosquito-borne viral disease, can be attributed to climate change. The study, which analyzed approximately 1.5 million dengue infections across 21 countries in Asia and the Americas between 1993 and 2019, found that rising temperatures were specifically responsible for 19% of dengue infections. If action isn’t taken to mitigate global warming, projections show that this figure may rise to 60% by 2050.

This is the first time that climate change has been causally linked to the spread of dengue, according to the researchers. Mosquitoes, which spread the disease, are cold-blooded and their internal temperature varies with the environment. Warmer temperatures lead to faster mosquito growth and reproduction, increasing the number of pests that can bite and spread disease.

The study focused on dengue because it has an optimal temperature range for transmission, meaning global warming is likely to make it more suitable for the disease to spread. The researchers found that there is an optimal temperature range in which mosquitoes can transmit dengue to humans, with infection rates peaking at around 84.2 F (29 C).

In some areas of Peru, Mexico, Bolivia, and Brazil, where dengue is already endemic, infections may rise by more than 150% in the next few decades as temperatures increase. However, beyond a certain threshold, disease transmission starts to fall because mosquitoes start dying before they can infect people.

Actions to reduce carbon emissions and mitigate global warming could help prevent a surge in global dengue infections, the researchers say. If carbon dioxide emissions decline to net-zero around or after 2050, there could be a 7% smaller increase in dengue cases overall, or 30% less in some countries.

While the study did not consider the U.S. in their analysis, there is emerging evidence that climate change is making dengue more common in the states. Locally acquired cases have been reported in California, Texas, Florida, Hawaii, and Arizona in recent years. The Centers for Disease Control and Prevention warned in June 2024 that Americans would face a higher-than-normal risk of dengue infection that summer due to rising cases worldwide.

Overall, the study highlights the potential impact of climate change on the spread of dengue fever and the importance of taking action to mitigate global warming to prevent future outbreaks.