Just days after the Centers for Disease Control and Prevention issued a warning about the increased risk of dengue virus infections in the United States, Florida health officials released an alert this week about two confirmed cases of locally acquired dengue fever in the Florida Keys. The warning means the people affected by the virus didn’t acquire it while traveling elsewhere.
The CDC and Florida advisories come in the wake of Puerto Rico declaring the mosquito-borne disease a public emergency in the spring and, earlier, a warning from the World Health Organization that dengue’s “unprecedented” global surge poses a “substantial public health challenge” with a high risk of increased transmission in many parts of the world, including the Americas, Africa, and Asia.
The situation is especially serious in Latin America, where upwards of 9.7 million cases have already been reported in 2024, according to the CDC. That’s double the number reported by the region for all of 2023—and we’re only halfway through the year.
Here’s what travelers need to know.
What is dengue fever?
Dengue is a viral infection spread by mosquitoes, explains the World Health Organization. The virus is most common in tropical and subtropical climates.
Only about 1 in 4 people infected with dengue will get sick, per the CDC. Among those, symptoms can be mild or severe. The severe version can be life-threatening.
What are the symptoms of dengue?
Common symptoms of mild dengue include fever; aches and pains in the eyes, muscles, joints, and bones; nausea or vomiting; and a rash. Symptoms usually last 2 to 7 days.
In some cases, though, severe dengue develops and can result in shock, internal bleeding, organ failure, and even death. You should seek emergency medical treatment if you start to experience belly pain or tenderness, bleeding, or extreme fatigue. Hospitalization may be required.
Those who have had dengue previously are more likely to develop severe infections, NBC News reports. As there are four types of virus that cause the disease, a person can get it up to four times in a lifetime.
Is there a vaccine for dengue?
According to the Washington Post, only one vaccine, Dengvaxia, has been approved for use in the United States. It provides protection against all four dengue types, but is only approved at the moment for kids ages 9 to 16 living in high-risk areas like Puerto Rico. And supplies are expected to run out by 2026.
The virus has no known cure. Your best course of action is to avoid, if possible, getting bitten by an infected mosquito in the first place.
Where is dengue on the rise?
Countries with tropical and subtropical climates tend to have the highest rates of mosquito-borne illnesses, given the insects’ preference for hot and humid conditions.
Tropical spots in Africa have experienced frequent outbreaks, with Burkina Faso reporting the continent’s most cases in 2023, per WHO data, and Mauritius undergoing its first-ever significant dengue spike last winter and spring.
In Asia, high numbers of dengue infections have been reported in recent years in Bangladesh, Malaysia, Thailand, and Vietnam.
The WHO’s color-coded map tracking 2024’s global cases is dark red in much of South America, indicating the severity of the viral surge in places such as Brazil, Argentina, Peru, and Colombia.
As for the United States, the CDC’s tracker has logged a total of 2,241 infections for 2024 so far—and 1,498 of them were in Puerto Rico. Next comes Florida (with 197), New York (134), and Massachusetts (50). To put that into perspective, only 205 U.S. cases were logged in 2021.
Why is dengue getting worse?
One likely culprit is climate change, the Washington Post found. If mosquitoes like warmer, wetter weather, after all, there’s now more of that to go around—and in more places.
You’ll note, for instance, that two of the U.S. locations experiencing a dengue spike mentioned above—New York and Massachusetts—haven’t historically been known for their tropical weather. But as heat and storms increase throughout the world, the number of mosquitoes and transmissions of the many illnesses they spread are bound to go up as well.
How to prevent mosquito bites when you travel
Find out whether you’re visiting an area with increased risk of dengue. The CDC maintains a helpful database, with country-specific advice and information to help you plan and pack accordingly.
Use insect repellant. Make sure the product you select is approved by the Environmental Protection Agency, and always read the instructions on the label for important info about application, reapplication, and whether the product is safe for children.
Wear loose-fitting, long-sleeved shirts and pants when you’re in places with higher risks of encountering mosquitoes.
When indoors, stay in places, if possible, with air conditioning and screens on windows and doors.
For more tips, go to CDC.gov.
Related: How to Avoid Ticks While Enjoying the Outdoors This Summer