CDC warns of increased risk of dengue fever infections. Here's what experts say about mosquito-borne illnesses.

The CDC has issued a new advisory amid rising cases of dengue infections in the Americas.
The CDC has issued a new advisory amid rising cases of dengue infections in the Americas. (Luis Robayo/AFP via Getty Images)

Federal health officials are warning that dengue fever risks are elevated in the United States as cases in the Americas for the first half of 2024 are already more than double last year's rates. This year has also set a record for global cases of the potentially fatal mosquito-borne illness, the Centers for Disease Control and Prevention said in a June 25 advisory.

Rising global temperatures are fueling a similar boom of dengue-infected mosquitoes, the CDC said. That's particularly concerning during the summer when Americans are more likely to travel to territories and countries with high rates of the virus, including to Puerto Rico, which has declared a public health emergency due to its nearly 1,500 cases of the illness, the agency said.

What does this mean for you, and how can you reduce your risk of a mosquito-borne illness? Here's what to know.

Surges in cases are happening closer to home this year. There have been more than twice as many cases of dengue fever across North, South and Central America — more than 9.7 million — in the first half of 2024 than there were in all of 2023, the CDC said.

In Puerto Rico, at least 1,498 people have caught dengue from mosquitoes, prompting the local government to declare a public health emergency. And 745 U.S. travelers have been infected, the CDC notes. Most cases of dengue among residents of U.S. states are acquired from mosquitoes during travel to other territories or countries. This year's rate of these travel-associated infections is higher than usual, and cases are being reported in states that don't normally see dengue fever infections.

The virus is always prevalent in the territories Puerto Rico, American Samoa, Micronesia, the Marshall Islands and Palau. And, historically, there are "sporadic cases or small outbreaks" of people bitten and infected with dengue locally in Florida, Hawaii and Texas, the CDC said.

"As more individuals with dengue in their blood" from being bitten by mosquitoes carrying the disease in parts of the world where the virus is prevalent "are traveling ... you can start to see local transmission," Dr. Amesh Adalja, a Johns Hopkins University Center for Health Security senior scholar, tells Yahoo Life.

In the past two years, dengue fever has been locally transmitted from mosquitoes in Arizona and California, too. Adalja says that these cases are rare but can happen anywhere, typically when someone travels to a place with endemic dengue, gets bit by a mosquito carrying the disease and brings it back to their home state, where they are bitten by another mosquito that can then transmit to yet another person.

Adalja says your level of concern should vary widely, depending on where you live. For those who live in Florida or near the Mexico border, risks are considerably higher (and more precautions should be taken) compared to someone living in, for example, Colorado.

But it's certainly worth checking the dengue activity in places you're planning to travel, he says. Dengue can be dangerous, causing high fever, headache, body aches, nausea and rash, per the World Health Organization. In severe cases, it can be fatal.

Amid the surge in cases, the CDC is urging health care providers to be vigilant and test people who have fevers and have been in "areas with frequent or continuous dengue transmission within 14 days before illness onset."

Adalja says that aside from minimizing standing water around your property, there isn't too much for an average American in the continental U.S. to do. However, if you're going to travel to areas like Puerto Rico, he says to ask tour guides or hotels about areas that have a lot of mosquitoes. He also recommends always wearing repellant and keeping as much of your skin covered as possible if you're going to be near, for example, swampy areas, where the insects congregate and breed.

Speaking to Yahoo Life last year amid an uptick in dengue, malaria and West Nile cases, Dr. William Schaffner, an infectious disease specialist at the Vanderbilt University School of Medicine, also suggested wearing repellant "if you’re living in areas where these cases have occurred."

The CDC recommends picking an insect repellent that’s registered with the Environmental Protection Agency and contains one of the following ingredients:

  • DEET

  • Picaridin

  • IR3535

  • Oil of lemon eucalyptus (OLE)

  • para-menthane-3,8-diol (PMD)

  • 2-Undecanone