It started with a horsefly bite. Or, at least, that’s what doctors think.

Steve Wilson didn’t have a cut when he cast his first line in the Gulf off the coast of Mississippi on Saturday, but Amanda Wilson remembers her husband pausing to apply bug spray.

Lifelong Mississippi residents and avid fishers, the Wilsons have heard all the horror stories about Vibrio vulnificus, a dangerous flesh-eating bacteria found in warm, brackish coastal waters and raw or undercooked seafood. It’s rare to contract it at all, but one in five people who develop severe infection die, sometimes within 48 hours.

Amanda Wilson, a 47-year-old nurse, said she’s exceedingly careful when it comes to Vibrio. The Wilsons never swim in the Gulf and stay on Cat Island’s south side while fishing, where the open waters are thought to be less prone to bacteria propagation. Before they hit the water, they always check for cuts and other open wounds, gateways through which vibrio can enter the body and trigger necrotizing skin infections, bloodstream infections or gastrointestinal illness.

Later on Saturday afternoon, when they launched their boat into Jourdan River from McLeod Park, the Wilsons made sure to head farther upriver away from the Gulf before getting in the water.

“It’s crazy because it was just a typical day,” Amanda Wilson said.

Despite all the precautions, 50-year-old Steve Wilson awoke early the next morning to searing pain near his right ankle, pain so severe he couldn’t walk. His ankle was swollen and hot, Amanda Wilson said, and she noticed what looked like a small bruise at the center of the swelling.

Vibrio was her first thought.

She rushed her husband to Slidell Memorial Hospital, and by the end of the 45-minute drive from Necaise Crossing, he’d developed a fever of 103.6 degrees and was septic. Doctors there confirmed the worst: he’d contracted Vibrio vulnificus and the infection was eating away at the flesh of his foot and leg.

After surgery and a cocktail of antibiotics, Steve Wilson’s leg had finally shown some improvement by Tuesday. But he was still in the ICU, and doctors warned his wife that infections like these can take dramatic turns practically overnight.

“We have to take it day by day,” she said. “It’s a day by day issue.”

Last year’s spike in cases

Cases of Vibrio vulnificus spiked across the Gulf Coast last year, prompting Louisiana public health officials to issue warnings about a sharp increase in hospitalizations and deaths related to the bacterium last fall.

Most Gulf states are seeing fewer cases so far in 2026, though health officials say infections peak between May and October, when Gulf waters are warmest and residents are most likely to swim and fish. Rising summer temperatures and runoff from storms can also help Vibrio flourish.

In Mississippi, where a total of 58 Vibrio cases were reported in 2025, seven cases have been reported so far this year, none of which have proven fatal, according to data collected by the Mississippi State Department of Health. The rarer, flesh-eating species Vibrio vulnificus has been behind just one of those cases.

Twelve Vibrio infections have been reported to the Alabama Department of Public Health so far this year, and three of those cases involved Vibrio vulnificus specifically, according to ADPH spokesperson Ryan Easterling. One case proved deadly.

A total of 19 Vibrio cases were reported in Alabama last year, Easterling said.

Louisiana’s numbers were not immediately available, but by September of last year, Vibrio vulnificus had led to 26 hospitalizations and five deaths, compared to annual average of about 10 cases and one death over the previous decade.

Preventing infection

With much of Vibrio peak season left to go and an upcoming warm holiday weekend, Amanda Wilson worries cases along the Gulf Coast could spike.

She and doctors aren’t sure where exactly Steve Wilson contracted the infection. Could it have been when he poured a cup of Gulf water onto his boat to wash away a little blood from a caught fish, using his foot to splash the water around? Was it his dunk in the Jourdan River, shortly after the area saw massive flooding from Tropical Storm Arthur?

“The thing I want people to know is to think outside the box,” Amanda Wilson said.

It’s easier than you might think to become infected, she said. It could be cutting yourself on something that’s been in the water recently, eating a bad oyster or going for a swim in the Gulf with a fresh tattoo.

Public health officials advise those with chronic health conditions to avoid eating raw oysters or undercooked shellfish, keep wounds covered when in brackish water and wear protective gloves when handling seafood. Wash any cuts exposed to seawater or raw seafood with soap and clean water, and seek medical care immediately if a wound shows signs of redness, swelling or blistering.

“It takes just as little as a bug bite that we were not even aware of,” Amanda Wilson said.