As summer ushers in peak mosquito season, health and vector control officials are bracing for the possibility of another year of historic rates of dengue. And with climate change, the lack of an effective vaccine, and federal research cuts, they worry the disease will become endemic to a larger swath of North America.
About 3,700 new dengue infections were reported last year in the contiguous United States, up from about 2,050 in 2023, according to the Centers for Disease Control and Prevention. All of last year’s cases were acquired abroad, except for 105 cases contracted in California, Florida, or Texas. The CDC issued a health alert in March warning of the ongoing risk of dengue infection.
“I think dengue is here with us to stay,” said infectious disease specialist Michael Ben-Aderet, associate medical director of hospital epidemiology at Cedars-Sinai in Los Angeles, about dengue becoming a new normal in the U.S. “These mosquitoes aren’t going anywhere.”
Dengue is endemic — a label health officials assign when diseases appear consistently in a region — in many warmer parts of the world, including Latin America, India, and Southeast Asia. Dengue cases increased markedly last year in many of those places, especially in Central and South America.
The disease, which can spread when people are bitten by infected Aedes mosquitoes, was not common in the contiguous United States for much of the last century. Today, most locally acquired (meaning unrelated to travel) dengue cases in the U.S. happen in Puerto Rico, which saw a sharp increase in 2024, triggering a local public health emerg …