Florida health officials are urging caution on the water after four people died and seven others were sickened this year from vibriosis, a potentially deadly illness caused by the bacterium Vibrio vulnificus, according to the Florida Department of Health.

The department says the increase is linked to flooding from Hurricane Helene, which pushed more people into contact with contaminated saltwater and brackish water. A similar spike occurred after Hurricane Ian in 2022.

The Centers for Disease Control and Prevention notes that Vibrio vulnificus naturally lives in warm coastal waters and is most commonly contracted by eating raw or undercooked shellfish, particularly oysters, because the bacteria tend to concentrate inside shellfish. It can also infect swimmers through an open wound, new tattoo or recent piercing.

Mild infections can cause diarrhea, stomach cramps, nausea, vomiting and fever. But in severe cases, the bacteria can enter the bloodstream, causing dangerously low blood pressure, blistering skin lesions and necrotizing fasciitis — commonly called flesh-eating disease. In such cases, doctors may have to amputate infected limbs to stop the spread of tissue damage, according to the CDC.

The CDC estimates about 80,000 vibriosis infections occur in the United States each year, with 52,000 linked to contaminated food. Severe wound infections are rare but progress quickly, making early medical attention critical.

Health officials stress that Florida’s waters and seafood remain safe for most people. “This isn’t about staying out of the water or avoiding seafood altogether,” a Florida Department of Health spokesperson says. “It’s about making smart choices — especially if you’re at higher risk.”