The Aedes mosquitos, which spread dengue, thrive in warm conditions. Credit: Soumyabrata Roy/NurPhoto via Getty
Major dengue outbreaks in the Americas tend to occur about five months after an El Niño event — the periodic warming of the Pacific Ocean that can disrupt global weather — a study1 has found. Meanwhile, local outbreaks tend to happen about three months after summer temperatures peak and roughly one month after peak rainfall.
The study, published today in Science Translational Medicine, paints a clearer picture of the relationship between the mosquito-borne disease and climatic conditions in the Americas, a region that saw a record-breaking 13 million cases in 2024.
Dengue is caused by four closely related viruses and spread by the Aedes species mosquitoes. There is no specific treatment, and the disease can lead to fever, bone pain and even death.
The research relied on roughly three decades of surveillance data from 14 countries. Cases in the region tended to rise and fall in sync, on average six months apart, even in places as far as 10,000 kilometres apart.
The findings are “useful to anticipate when a region might expect to see an epidemic, which can help inform planning and preparedness”, says Talia Quandelacy, a co-author and an infectious-disease epidemiologist at the University of Colorado School of Public Health in Aurora. She notes that, although the link between dengue and climate is well known, what stands out in the findings is how this association plays out across the entire continent, “especially given that it’s such a climatically diverse region”.