Federal health officials are warning that cases of dengue are rising higher than expected this year in the U.S. amid a record number of global cases of the mosquito-borne disease.
As of Monday, there have been more than 9.7 million dengue cases reported in the Americas, which is twice as many reported in all of 2023, the Centers for Disease Control and Prevention said in a health advisory issued Tuesday.
In the U.S., there have been 2,241 confirmed cases so far, compared to 3,036 during all of 2023. This year’s total includes 1,498 cases in Puerto Rico, which declared a public health emergency in March, a month that’s historically a low-dengue season.
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The vast majority of dengue cases in the continental U.S. will occur in travelers who were infected by a mosquito while visiting areas with a risk of dengue. These areas are typically in tropical and subtropical regions, where dengue transmission peaks during the warmer and wetter months, the CDC said.
“Dengue cases are likely to increase as global temperatures increase,” the CDC said. “Higher temperatures can expand the range of the mosquitoes that spread dengue, as well as affect other factors that facilitate virus transmission like faster viral amplification in the mosquito, increased vector survival, and changes in reproduction and biting rates.”
Florida has seen the most cases this year, with 197 reported, while New York has seen the second-highest, with 134, according to the CDC.
Last year, there were 179 locally acquired cases in Florida, according to CDC data. Local transmissions have also previously been seen in Hawaii, Texas, Arizona and California.
The Florida Department of Health last week reported a locally acquired case of dengue in Hillsborough County, which is in Tampa.
The disease can take up to two weeks to develop, with illness generally lasting less than a week. Its symptoms include fever, headache, nausea, vomiting, rash, muscle and joint pain, and minor bleeding.
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Severe cases can develop within a few hours of transmission and they will usually require hospitalization. Most severe cases involve hemorrhage, shock, organ failure and death.
Health officials advise the public to use mosquito repellents during and immediately after travel to areas with dengue transmission and to wear loose-fitting, long-sleeved pants and shirts to prevent bites.
Stagnant outdoor water should also be dumped or drained to reduce mosquito egg-laying sites.