CDC Issues Warning about Dengue Fever in Time for Spring Break
CDC said it’s possible that local transmission could rise in the continental US in areas that have mosquitoes that can carry the virus.
Through 2024, I kept a close eye on the news about cases of dengue fever spreading across the county.
Dengue fever is a mosquito-borne viral disease that occurs in tropical and subtropical areas of the world. It is caused by any of four closely related dengue viruses and is primarily transmitted to humans through the bite of infected Aedes mosquitoes, particularly Aedes aegypti.
Most dengue cases are mild, with about 1 in 4 infected people developing flu-like symptoms. However, in some cases, dengue can progress to a severe form called dengue hemorrhagic fever or dengue shock syndrome, which can be life-threatening.
The classic symptoms of dengue include aches and pains (eye pain, typically behind the eyes, muscle, joint, or bone pain). Hence, its nickname, “break-bone fever”.
Last fall, I reported on an ‘unprecedented cluster’ of locally acquired dengue fever in Los Angeles County. It was usually because most American dengue cases were associated with travel abroad.
Earlier in 2024, I shared the news that Florida health officials issued a dengue fever alert after a second case of a locally acquired infection was reported in the Keys and several more were reported in Miami-Dade County, and that 200 New York and New Jersey residents have been diagnosed with “break-bone Fever.”
And toward the end of the year, there were reports that Texas had its first case of locally transmitted dengue fever.
Now. just in time for spring break in the tropics, the Centers for Disease Control and Prevention (CDC) has issued a Health Alert Network (HAN) notice regarding the ongoing risk of dengue virus infections in this country.
A “record number” of dengue fever cases were identified among U.S. travelers last year — a total of 3,484, an 84 percent increase compared to the year before.
“This trend is expected to continue with increased dengue activity in endemic areas in 2025,” the warning from the CDC reads.
Dengue activity remains high in some parts of the United States and around the world, and transmission of the disease remains high in the Americas and the U.S. territories of Puerto Rico and the U.S. Virgin Islands.
Dengue is more easily spread during the warmer months, placing spring and summer travelers at an increased risk of contracting the disease.
The CDC is monitoring for all four dengue viruses and notes that a public health emergency related to dengue is still in effect for both Puerto Rico and the US Virgin Islands.
All four DENV serotypes were reported among travelers returning to the United States in 2024. DENV-3 was the most common serotype identified in 2024, but the proportion of cases caused by DENV-4 has been increasing in recent months.
During October 2024–January 2025, DENV-4 was identified in 50% of travel-associated dengue cases among cases with DENV serotype available. In addition, DENV-3 has re-emerged after a prolonged absence in multiple countries across the Americas region during 2024 and 2025. Introductions of new serotypes have been associated with increasing size and frequency of dengue outbreaks, as well as more severe clinical outcomes in patients with previous DENV exposure.
In Puerto Rico, reported dengue cases have remained above the outbreak threshold since February 2024. A public health emergency was declared in March 2024 and remains in effect. In 2024, 6,291 cases were reported, more than 52% (3,292) required hospitalization and there were 13 deaths. As of March 7, 2025, 936 cases have been reported, representing a 113% increase compared to the same period in 2024.
In the U.S. Virgin Islands, a dengue outbreak was declared in August 2024 and remains in effect. A total of 208 locally acquired cases were identified in 2024, and 30 in 2025 as of March 7, 2025.
Additionally, the CDC said it’s possible that local transmission could rise in the continental US in areas that have mosquitoes that can carry the virus.
Interestingly, a vaccine for dengue, Dengvaxia, is the only dengue vaccine approved for use in the US. This vaccine is specifically recommended for routine use among children aged 9–16 years with laboratory-confirmed previous dengue virus infection and living in areas where dengue is endemic. There are no dengue vaccines currently approved for use by American travelers who are visiting but not living in dengue-endemic areas.
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Comments
DDT is still the best preventative of mosquito-borne illnesses. Far more effective and less toxic than CDC pronouncements or problematic vaccines.
Good luck getting DDT back on the market and even if you did there’s a fair amount of resistance in mosquito populations to it. And not to mention that it’s pretty effective on non-target insects as well. There are products available to professionals that will knock them back without killing everything else in sight.
DDT was massively overused, back in the day. We were out to kill off every last bug on the planet.
Used properly, it is, or could be, very useful.
Why is the cdc still around?
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