Health experts issue warning on emerging threat to Americans traveling for spring break: 'Worst year ... on record'

The CDC has issued a warning for American travelers to popular tourist spots, as dengue fever cases are surging across the Americas.

What's happening?

As of late March 2025, Mexico had already reported 20,000 cases of this mosquito-borne disease since the beginning of the year, DailyMail.com reported. Other popular destinations like Puerto Rico and the U.S. Virgin Islands have also seen unusually high transmission rates, according to the news site.

Nearly 1,000 cases have been reported in the United States in 2025, DailyMail.com added. This included locally acquired infections of the dengue virus, which have been on the upswing in recent years, especially in states like California and Florida.

The CDC said that "this trend is expected to continue with increased dengue activity in endemic areas in 2025."

Why is the dengue outbreak concerning?

Dengue is a mosquito-borne viral infection that can lead to symptoms like high fever, severe headache, nausea, and vomiting, according to the World Health Organization. Severe cases can result in bleeding gums or nose, weakness, blood in vomit or stool, and even death.

The current surge in infections comes after a record-breaking year for the disease — in fact, the World Mosquito Program called 2024 the "worst year for dengue cases on record." 

While surges in dengue tend to be cyclical, according to Dr. Albert Ko, a professor at the Yale School of Public Health who spoke with CBS News, locally acquired cases in southern U.S. states can also be attributed to rising temperatures.

In fact, other mosquito-borne diseases like malaria and Oropouche are also on the upswing as a warmer planet is helping mosquitos to move into new habitats that were once too cold for them. For example, scientists from the University of Helsinki recently discovered a mosquito species in Finland that was previously unrecorded there.

What's being done about mosquito-borne diseases?

The CBS News report on the dengue outbreak recommended that people take preventative actions like rearranging travel to countries with known dengue risk to times of the year when transmission is lower and wearing protective clothing and repellents.

However, local governments are also looking for ways to help decrease the spread of mosquito-borne diseases by culling the population of these blood suckers. For instance, when San Diego County discovered its first-ever locally acquired case of dengue in fall 2024, it quickly sprayed for mosquitoes at about 170 homes. Plus, one neighborhood in the Philippines recently launched a bounty program that is paying residents to bring in mosquitoes, dead or alive.

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