A Deadly Mosquito-Borne Illness Rises as the U.S. Cuts All Climate-Health Funding

change is causing cases of the disease to skyrocket. The abrupt subversion of the personnel and institutions tasked with responding to a threat like dengue bodes poorly for future health crises as climate change causes carriers of disease like mosquitoes, fungi, and ticks to expand their historical ranges and infiltrate new zones.

“The disease pressure in the last couple of years is very dramatic and it’s going in one direction — up,” said Scott O’Neill, founder of the World Mosquito Program, a nonprofit organization that infects mosquitoes with a naturally occurring bacteria to fight disease in 14 countries. For example, Brazil — the country that consistently registers the highest number of dengue cases — recorded a historic 10 million cases last year. The country reported 1.7 million cases in 2023.

The two types of mosquitoes that most often infect humans with dengue, Aedes aegypti and Aedes albopictus, thrive in the warm, moist conditions made more prevalent by rising atmospheric temperatures caused by fossil fuel combustion. The vast majority of annual dengue cases are asymptomatic, but about 25 percent of people infected, depending on the population, develop symptoms like fever, headache, and joint pain. A small percentage of those cases result in severe sickness, hospitalization, and even death.

The number of severe dengue infections corresponds roughly to the size of the pool of people infected every year. In 2023, when there were 6 million total dengue infections, 6,000 people died. In 2024, a year when there were more than 13 million cases registered globally, over 8,000 people died. 

There is no cure for dengue. Patients in wealthier countries generally fare better than patients in developing regions with limited access to medical interventions like blood transfusions and places where waves of dengue patients overwhelm already-strained healthcare systems. Two dengue vaccines are available in some countries, but both have serious limitations in terms of efficacy and how long they confer immunity. 

The NIH began taking climate change and health research seriously in 2021, and the institutes have funded dozens of studies that probe every aspect of the climate-dengue connection since. NIH-funded researchers have sought to understand how warmer temperatures shift the geographic ranges of Aedes mosquitoes, which factors predict dengue outbreaks, and how communities can protect themselves from dengue following extreme weather events.

These studies have taken place in the southeastern U.S., where dengue is becoming more prevalent, and internationally, in countries like Peru and