Rare, deadly 'flesh-eating' bacteria is washing up on Florida's beaches. Here's how to stay safe.

• Clumps of murky brown seaweed are washing up on Florida's Miami Beach and Key Biscayne.
• A new study says the clumps are magnets for bacteria called Vibrio vulnificus.

Giant clumps of seaweed are washing up on Florida's beaches, and they may contain dangerous "flesh-eating" bacteria, researchers warn.

This is the latest concern to emerge from the Great Atlantic Sargassum Belt, an ominous mass of murky brown seaweed that has been blooming in the Atlantic Ocean since 2018. Scientists believe it is largely fueled by human activity, InfoAmazonia reported, with deforestation and intensive soybean farming in the Brazilian Amazon sending nitrogen and phosphorus into the ocean.

While many types of seaweed are beneficial for human health and the ecosystem, this 5,000-mile-wide bloom is causing power outages and injuring fish. It is also emitting hydrogen sulfide, which has been linked to heart infections and pregnancy complications for people living in coastal regions — not to mention it makes the beaches smell like rotten eggs.

Now, researchers are sharing another reason for beachgoers to steer clear of the seaweed clumps landing across Miami Beach and Key Biscayne: They are fertile ground for a bacteria species called Vibrio vulnificus, which can cause life-threatening "flesh-eating" infections.

"I don't think at this point, anyone has really considered these microbes and their capability to cause infections," said Tracy Mincer, assistant professor of biology at Florida Atlantic University (FAU), in a news story published by FAU. Mincer co-authored the new study in the journal Water Research. "We really want to make the public aware of these associated risks," Mincer told FAU.

What is Vibrio?

Vibrio vulnificus is a type of bacteria that thrives in warm water. According to Miner's team at FAU, Vibrio "are the dominant cause of death in humans from the marine environment."

When ingested — for example, by eating contaminated shellfish — Vibrio can cause watery diarrhea, fever, and stomach cramps, usually within 24 hours.

Vibrio can also enter the bloodstream through a break in the skin, such as a cut or bite. In some rare cases, that can cause a "flesh-eating" infection called necrotizing fasciitis, which is fast-moving and can be fatal within days.

Standard treatment of necrotizing fasciitis starts with IV antibiotics, to curtail the infection and prevent complications such as organ failure and sepsis. If the infection progresses, the next step is surgery to cut out the infection, which may include amputation of infected limbs.

Symptoms of Vibrio infection

According to the CDC, early symptoms of a Vibrio infection include:

• Watery diarrhea and stomach cramps
• Nausea
• Fever and chills
• Blistering skin, which may present as black dots
• Low blood pressure
• Pain, swelling, or warmth around an infected wound

How to avoid flesh-eating bacteria at the beach

Vibrio infections are rare. Florida has recorded 437 cases since 2013, and 101 deaths, according to Florida's Department of Health.

To avoid a Vibrio infection, first make sure to stay away from clumps of seaweed on the beach.

Keep any open wounds, including new piercings or tattoos, covered with a waterproof bandage. It's particularly important to avoid getting seawater or juices from undercooked fish in an open cut — even unintentional splashes while walking near the water.

If you do get saltwater or juices from raw fish in a wound, wash it immediately with soap and water. And if you start experiencing the symptoms of a Vibrio infection, seek medical attention.