A concerning mosquito-borne disease may be on the rise in the United States. Recent data from the Centers for Disease Control and Prevention indicates a significant spike in dengue cases.
This month, CDC researchers shared their findings, revealing nearly 4,000 dengue cases reported in 2024, marking a record high that surpasses the usual annual average. While most cases were linked to travel, the team suggests that the risk of local transmission appears to be growing.
“Dengue poses a public health threat to individuals of all ages,” they noted in their analysis, which was published in the Morbidity and Mortality Weekly Report (MMWR).
‘Bone-breaking’ pain
Dengue is a viral disease transmitted by mosquitoes. Generally, initial infections might not present symptoms, but about one in four people will experience flu-like symptoms. Some are struck by such severe pain that it’s often likened to the agony of a broken bone, hence the nickname “breakbone fever.”
Between 1% and 5% of those with dengue face severe complications, including internal bleeding or shock, which can be life-threatening. There are four main serotypes of the virus, and immunity from one type does not protect against others. In fact, experiencing a second infection from a different type can increase the chances of severe dengue.
The mosquitoes that spread dengue, known as Aedes, primarily inhabit tropical regions. However, their range has been expanding, along with the disease itself. The past few decades have seen a notable rise in worldwide dengue cases, and things have escalated recently. The World Health Organization reported over 14 million cases globally in 2024, a “historic high” and more than twice the total from 2023, which was already unprecedented. Most of these cases were concentrated in the Americas.
The CDC noted that 3,798 dengue cases were reported in the U.S. for 2024, a staggering 359% increase compared to the average from 2010 to 2023 (which stood at 828 cases). Among these, 108 individuals suffered from severe dengue, and tragically, six passed away.
The future of dengue
The surge in U.S. cases likely mirrors the global trend; around 97% of reported cases were travel-related, indicating they were contracted abroad.
However, over 100 locally acquired cases were also recorded in 2024. States like Florida, California, and Texas saw infections spread across various counties, suggesting that the virus was introduced multiple times rather than stemming from one large outbreak. There’s a real possibility that dengue could establish a consistent presence in the U.S., given that Aedes mosquitoes are widespread throughout many parts of the country.
“While these instances didn’t lead to major outbreaks in the continental U.S., they highlight an increasing risk for locally acquired cases. This underscores the necessity for improved surveillance, vector control, and public health responses in areas with capable mosquito populations,” the authors pointed out. Notably, about half of U.S. counties host dengue-carrying mosquitoes, and three-quarters have the warm climates that favor them.
Fortunately, the year 2025 was somewhat less alarming in terms of dengue, though over six million suspected and confirmed cases were still reported in the Americas. The actual number is likely far higher, as many infected individuals may not show symptoms. Thus, while 2024 was particularly challenging for dengue both in the U.S. and worldwide, it seems poised to remain a persistent and escalating issue, influenced by factors such as climate change.
