How to stay safe from dengue fever — and how your community can help too

As cases rise around the world, the U.S. health officials are warning Americans about dengue fever, a potentially fatal disease carried by mosquitoes. The disease is endemic — or ever present — in many parts of the world, including Puerto Rico and other U.S. territories. And cases have been reported annually among Americans returning from travel, as well as from local transmission in a few states, including Florida, Hawaii and Texas.

But this year is different. Massachusetts, where the disease has been historically rare, has reported 50 infections in travelers so far in 2024, and is on track for a record-breaking number of annual cases. Puerto Rico has declared a state of emergency, the U.S. has reported more travel-related cases than would typically be expected (745, according to the Centers for Disease Control and Prevention) and local transmissions are cropping up as well. Seven have been reported in Florida, for example, including two in the Florida Keys.

The CDC is warning of an increased risk of dengue fever for Americans, but says the risk is still generally low. Nonetheless, we asked experts what can be done to keep safe. Here’s what they had to say.

What to do: On the individual level at home

First, it’s important to acknowledge that the risk of being bitten by a dengue-infected mosquito near your home if you live in the continental U.S. is low, per the CDC. But there are steps you can take, experts say.

1. Protect your body. The main things you can do to keep yourself safe are “wearing mosquito repellent, avoiding areas known to harbor a lot of mosquitoes and wearing clothing that doesn’t expose a lot of skin,” Johns Hopkins infectious disease expert, Dr. Amesh Adalja, tells Yahoo Life.
2. Make your home less hospitable to mosquitoes. You can keep your home from harboring mosquitoes by “cleaning up junk in your yard,” Adalja says. Mosquitoes breed in standing water, and thrive in the areas around them. So getting rid of or covering things like sandboxes, plastic pools or other debris and receptacles that could accumulate water can help to slow population growth and keep mosquitoes from making themselves at home around yours.

What to do: On the individual level while traveling

For perspective, there have been 2,391 cases of dengue fever reported in U.S. states and territories since the start of 2024, per the CDC. A large majority of those (1,498) were reported in Puerto Rico, where the virus is endemic. Another 794 were acquired while people were traveling, while only 99 have been locally acquired outside of Puerto Rico.

The data is clear: You’re most at-risk while traveling, specifically to countries with high rates of dengue fever. According to the CDC, those include most countries and territories in Central and South America, including Mexico, Puerto Rico, Costa Rica and Brazil, several countries in Africa, and parts of Southeast Asia. You can find a full list here. While traveling, you can protect yourself by:

1. Stay away from mosquito-ridden areas. Adalja suggests asking your hotel, tour guides or other locals where there are lots of mosquitos. If you can, avoid these areas.
2. Gear up. Just as you would at home, try to keep your skin covered as much as possible and wear mosquito repellent, Adalja says.
3. Mind your legs. The mosquito species that carries dengue, Aedes aegypti, “are very skittish and adept at hovering around people, looking for the perfect opportunity to land and take a quick bite,” Chad Huff, a public information officer with the Florida Keys Mosquito Control District, tells Yahoo Life. “Often, they choose to gravitate towards the lower legs and ankles where they are less likely to draw attention or a slap.” So you might want to take extra care to cover and protect your lower body.
4. Watch for symptoms. Although up to 80% of dengue cases are asymptomatic, pay attention to how you’re feeling if you were bitten by any mosquitoes while traveling to a place with high dengue activity. Symptoms include high fever, head and body aches and nausea (“which probably will make people think they have COVID,” says Adalja). If you have these symptoms, see a health care provider and let them know about your recent travel and bites, so they can test you. While most illnesses are mild, the infection can cause potentially fatal internal bleeding, so you may be prescribed antiviral treatment. Adalja says antiviral treatment might also be advisable if you live in areas within the U.S. that currently have high dengue activity levels, including Key West, Fla.

While the rising incidence of dengue fever is concerning on a global level, Adalja says people don’t need to cancel their travel plans. “It’s an endemic disease all over the world,” he notes. The CDC’s advisory “isn’t against travel, it’s just saying it’s riskier.”

What to do: On the public health level

The species of mosquito that carries the dengue virus — as well as yellow fever, chikungunya and Zika — is still found all over the nation. “I think there’s a lot of complacency” around “vector control,” or efforts to keep populations of potentially disease-carrying mosquitoes low, says Adalja. To better combat dengue fever outbreaks, local, state and federal officials can:

1. Monitor mosquito pools. It’s not just people who can (and should) be tested for dengue and other mosquito-borne illnesses. County health departments can collect the insects from the slimy pools they gravitate towards and test them for a range of viruses. Some locales do this (Austin, Texas, recently detected two pools positive for West Nile virus), but a 2022 survey found that only about 24% of surveillance programs are “fully capable.”
2. Do public clean-ups. It’s one thing for individuals to do their part to clean up their own yards, but public litter provides even more opportunities for mosquitoes to breed, Adalja says. Communities — whether at the local or state level — “can organize the cleaning up of areas with high levels of mosquito breeding sites, similar to what happened in Miami Beach when it had local transmission of Zika,” Adalja says.
3. Use mosquitoes against themselves. “The most effective [approach] is when [health officials] release genetically modified sterile male mosquitoes, like they’ve done in Key West; Fresno, California; and parts of Texas,” Adalja says. Testing of this approach in other countries has shown it can reduce dengue cases by as much as 97%. Adalja says that in the U.S. there is a stigma attached to genetic modification, but adds that releasing mosquitoes infected with bacteria or that have been irradiated can help stem populations too.