Key TakeawaysVibrio vulnificus, a flesh-eating bacterium, is spreading northward from its traditional habitat in Gulf Coast watersInfections can develop from open wounds exposed to brackish water or from eating raw or undercooked seafood, particularly oystersThe bacteria pose the greatest risk to people with weakened immune systems, and severe infections have a high death rate.THURSDAY, Aug. 21, 2025 (HealthDay News) — Health experts across the country are issuing warnings about a surge in infections from a "flesh-eating" bacterium known as Vibrio vulnificus.Typically found in the warm, salty waters of the Gulf Coast, the bacteria are now appearing in new areas, with experts pointing to climate change as a key factor in their northward migration along the east coast, The Associated Press reports.The bacteria thrive in warm, brackish water — a mixture of fresh and saltwater found in estuaries and lagoons. While most infections are reported between May and October in Gulf Coast states, cases have been documented as far north as New England, where a recent case on Massachusetts’ Cape Cod prompted a public health alert.Vibrio vulnificus is a particularly dangerous type of Vibrio bacteria.While most of the more than 1,000 Vibrio illnesses reported each year in the U.S. are less severe, Vibrio vulnificus accounts for about 200 cases. As many as 1 in 5 cases end in death, much higher than other strains, according to the U.S. Centers for Disease Control and Prevention (CDC).A Florida man, Bernie Stewart, counts himself lucky to have survived a 2019 infection that required 10 surgeries over three months to remove decaying tissue.For him, the message is clear: "This ain’t nothing to play with.”People can become infected in one of two ways. The first is by eating raw or undercooked shellfish, especially oysters, which filter the bacteria from the water.The second and more common way is when the bacteria enter the body through an open wound, recent tattoo or piercing or other type of break in the skin while in the ocean or brackish water.Dr. Fred Lopez is an infectious diseases specialist at the LSU Health Sciences Center in New Orleans. He noted that the waters of the Gulf Coast represent "the perfect convergence of the right amount of salt and the right amount of heat to let this organism proliferate."Severe infection is more common in people with weakened immune systems, liver disease, diabetes, or other chronic illnesses, according to the CDC.Once in the bloodstream, the bacteria can cause severe, life-threatening illness. Antibiotics are the first line of defense, but some infections require aggressive treatment, including multiple surgeries to remove dead tissue, and in some cases, even amputation, the CDC says.Cases fluctuate from year to year and depend on factors like tropical storms, making it tricky to interpret disease data, according to a researcher at St. Jude Children’s Research Hospital in Memphis, Tennessee."It is really easy to sound unnecessary alarms because cases have increased, or feel too complacent because cases are low, [due to incomplete reporting]," said researcher Salvador Almagro-Moreno.Nonetheless, states like Louisiana have seen an alarming jump in cases this summer, with 20 reported infections and four deaths so far, according to The AP.More informationThe Florida Department of Health has more about Vibrio vulnificus.SOURCE: Associated Press, Aug. 20, 2025.What This Means For YouTo stay safe, people should avoid exposure of open wounds or broken skin to warm salt or brackish water, or to raw shellfish harvested from such waters..Sign up for our weekly HealthDay newsletter