So far in 2024, countries in North, South, and Central America and the Caribbean have reported almost 10 million cases of dengue fever. Puerto Rico even declared a public health emergency because 1,498 cases were diagnosed there in the first half of this year.

Only about a quarter of people who become infected develop symptoms such as nausea, rash, muscle aches, joint/bone pain, headache, or low white blood cell counts. But when it’s severe, dengue can cause dementia or be fatal.

Symptoms or none, if you have dengue and are bitten by a mosquito that then bites someone else, the disease can spread.

Does that mean people in the U.S. are at risk? No — and yes.

While the number of cases reported in the U.S. this year is three times what it was last year at this time, they appear to be a result of people returning from Asia, Africa, the South Pacific, and the U.S. Virgin Islands. Because dengue is only transmitted through the bite of an infected mosquito, there isn't much risk yet.

However, more and more Americans are traveling to places where they can bring dengue back with them.

And climate change is making parts of the U.S. more hospitable to the Aedes aegypti mosquito that's responsible for the spread.

Your best defense? When outside, use repellents with DEET. If it’s a spray, use it in a well-ventilated area. It's safe on your skin unless you have an open wound.

Get rid of all standing water near you. And wear protective clothing.