As water temperatures in the Chesapeake Bay continue to climb, so are reported cases of Vibrio vulnificus — a rare bacteria sometimes called “flesh-eating” that thrives in warm, brackish water and can cause serious infections through open wounds or contaminated seafood.
Maryland recorded 14 confirmed V. vulnificus cases in 2025, including an outbreak in Wicomico County tied to a crab feast, with three deaths attributed to the infections. Virginia reported 11 cases that year, including one fatality. More broadly, Maryland’s total vibriosis case count — covering all Vibrio species — has more than doubled since 2018, rising from about 100 cases to 260 in 2025, while Virginia saw a similar near-doubling over the same period. Combined, the two states logged more than 400 vibrio cases in 2025, though health officials say that figure likely undercounts actual infections, since many milder cases go undiagnosed.
“Climate change and warming waters are significant drivers of increased cases of Vibrio,” said Chesapeake Bay Foundation Maryland Staff Scientist Gussie Maguire. “It’s not new to the region, but we have been seeing increases in recent years.”
The bacteria also benefit from nutrient pollution in the Bay, according to CBF Virginia Science Manager Mike Gerel. “Vibrio feed on microscopic animals that rely on algae that can result from nutrient pollution — so the more algal blooms that develop, the greater the risk,” Gerel said. Restoration efforts like streamside buffers can help by filtering runoff and keeping headwater streams cooler as they flow into the Bay, he said.
The risks are real, but rare. According to CBF, people are statistically more likely to be hurt in a car accident driving to the beach than to contract Vibrio in the water. Shawn Everett of Norfolk, who cut his leg on an oyster cage and ended up in the emergency room, said the infection can turn serious quickly if untreated. “If you get a cut while you’re in the water, be sure to keep a close eye on it and see a doctor if needed,” Everett said.
Nationally, the CDC estimates about 80,000 vibriosis cases occur each year in the U.S., with roughly 52,000 resulting from eating contaminated food.
Health officials recommend a few basic precautions: avoid swimming with open wounds, shower after swimming in natural waters, and avoid swimming in local waterways for 48 hours after a major rainfall, when bacteria levels can spike. NOAA maintains a Vibrio vulnificus risk map for the Bay that the public can check before heading out on the water.
Most cases nationally are foodborne rather than wound-related, so properly cooking or handling shellfish remains the most effective precaution. Raw oysters remain a Bay tradition, and the seafood industry is subject to testing and regulation aimed at limiting bacterial risk — but those who want extra caution during the hottest months can opt for cooked preparations instead.
“Enjoy the Bay, enjoy your local waterways, and enjoy your oysters this summer,” Maguire said. “But be smart.”
This is a sensitive health topic; readers experiencing symptoms of a wound or foodborne infection after water or shellfish exposure should seek medical care promptly rather than relying on this article alone.
