Shortly after Hurricane Helene’s torrential rains and storm surge subsided, Florida’s Department of Health had a new, but familiar, problem on their hands. They recorded an increase in reported cases of vibriosis, characterized by skin swelling, redness, pain, and blistering at the site of a wound alongside fever and nausea. For some, the infection has been life-threatening. As of October 25, 2024, there have been 77 cases and 15 deaths, up from 46 cases and 11 deaths in 2023.
The culprit behind these infections is the naturally occurring, waterborne bacteria Vibrio vulnificus. Several news outlets have described V. vulnificus as a “flesh-eating” bacterial species, but experts say that this description is misleading. “They don’t actually disintegrate your flesh on contact, like the name implies,” noted Gabrielle Barbarite-McHenry, a microbiologist and public outreach officer at Florida Atlantic University. Symptoms during late stages of an infection can cause tissue necrosis around the open wound, but Vibrio cannot break down healthy, intact skin, even after prolonged exposure.
Vibrio are a group of marine bacteria that thrive in warm, brackish waters—where fresh water mixes with seawater—like the estuaries on the coast of Florida. While most species are harmless to humans, some, like V. vulnificus, can cause infections.
“They’ve always been here, and they always will be,” said Barbarite-McHenry. “I like to compare them to things like rip currents and lightning and sharks. It’s just part of what’s out in nature when [doing recreation] that you just need to be aware of and careful to prevent infection.”
Although rare, infections can occur when an individual with an open wound has prolonged exposure to water containing high levels of the bacteria or through the consumption of raw or contaminated seafood. Within hours to a few days following exposure, individuals may experience symptoms of vibriosis. V. vulnificus infections can become serious and life-threatening, especially for individuals with weakened immune systems.1 If the bacteria spreads to the bloodstream, fever, chills, shock, and death can occur.
During graduate school, Barbarite-McHenry’s research focused on fishermen who were exposed to the pathogen in the Indian River Lagoon, an estuary on Florida’s Atlantic coast. For individuals who died following a severe case of vibriosis, she said it was always the same story: “They got up really early, they went fishing, they had a cut, they got exposed, they went home and took a nap, and by the time they woke up, they were needing to go to the hospital, and it was too late for treatment. So it’s definitely a severe infection, but it’s very easy to prevent, if people are aware of it, or just proactive on the front end.”
In the US, Florida has the highest number of vibriosis cases, and most infections are reported in the summer months when water temperatures are the warmest and rainfall is the highest. This also coincides with hurricane season where subsequent storm surges and coastal flooding can cause lower salinities of local water areas, making it more hospitable for V. vulnificus. “On the west coast, where we’ve had a lot of flooding, that’s where we see infections from storm,” said Barbarite-McHenry.
The recent surge in vibriosis infections is not uncommon. In September 2022, Florida’s Department of Health reported an increase in infections and deaths following Hurricane Ian.2 In a 2023 paper published in mBio, researchers at the University of Maryland used metagenomics to profile microorganisms present in water and oysters along the Florida Gulf Coast following Hurricane Ian.3 In addition to V. vulnificus, the team identified a V. parahaemolyticus, another pathogenic Vibrio species that contributes to cases of vibriosis.
The study also showed that cases of V. vulnificus infections in Florida increased by five-fold between 1992 and 2022. Many experts worry that with climate change coastal communities will continue to experience an increased risk of vibriosis.4,5
“Things pop up around this time of year in the headlines, but these bacteria really are here year-round,” noted Barbarite-McHenry. “It’s common for infections to rise this time of year, but the best thing is that they’re very easy to prevent. People just need to be aware and take the necessary precautions.”
For more information on preventing Vibrio infection (vibriosis), visit the CDC and the FL DOH.
