CDC Warns of Increased Risk of Dengue Fever Infections in U.S.

The United States is at an increased risk for mosquito-borne dengue fever — which can be fatal in severe cases.

The alert comes as cases of the virus rise in the Americas. In the first half of 2024, more than 9.7 million dengue cases have been reported — that’s twice as many as in all of 2023, according to an alert issued by the U.S. Centers for Disease Control (CDC) this week.

Puerto Rico declared dengue a public health emergency in March when the cases reached more than 500; but now, the CDC says cases of dengue there have almost tripled, reaching 1,498. 

The CDC also notes that 745 cases have been identified among U.S. travelers, a number the agency calls “higher than expected.”

And limited “local spread” of the virus has been reported in Florida, Hawaii, Texas, Arizona, and California, the agency says.

About 1 in 4 people will develop symptoms, the CDC says.

Those who do may develop “high fever, headache, body aches, nausea, and rash. Most will get better in 1–2 weeks. Some people develop severe dengue and need care in a hospital,” says the World Health Organization. 

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Severe dengue can be fatal, WHO says — and those infected a second time are at greater risk of developing severe dengue.  

As the CDC says in its alert: “Know the warning signs for progression to severe dengue, which include abdominal pain or tenderness, persistent vomiting, clinical fluid accumulation, mucosal bleeding, lethargy or restlessness, and liver enlargement.”

Mosquito populations are on the rise — something the Environmental Protection Agency attributed to climate change in its report on another virus spread by mosquitos: West Nile Virus.

“Studies show that warmer temperatures associated with climate change can accelerate mosquito development, biting rates, and the incubation of the disease within a mosquito,” the EPA said.

The mosquitos that spread dengue are the same ones that spread Zika and chikungunya viruses, the CDC says.

The agency adds that they lay their eggs in standing water — such as around flower pots and on top of containers — and recommends wearing insect repellent, longer clothing, and taking steps to control mosquitos around your home.