As Summer Heats Up, Vibrio Comes Into Focus for the Bay

As the 2026 calendar turns to August, many people who live in the Chesapeake Bay watershed are itching to get out on—and in—the water.

But as climate change helps drive longer-term increases in water temperatures in the Bay, cases of Vibrio vulnificus—a rare, “flesh-eating” bacteria that thrives in brackish or salty waters—have been increasing in Maryland and Virginia in recent years as well.

People who become infected can develop painful skin rashes from exposure to seawater with open wounds, or can become sick from consuming improperly prepared seafood.

Shawn Everett of Norfolk knows this all too well. He cut his leg on an oyster cage several years ago—and ended up in the emergency room.

“Vibrio can be very serious if left untreated—I was lucky to get proper medical care in time. 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,” he said.

“It’s concerning to see cases becoming more common as water temperatures continue to rise.”

As Shawn’s case demonstrates, cases can clearly be serious. But they are still relatively rare—and treatable if people with symptoms seek medical help immediately.

Here’s what to know about Vibrio vulnificus for people in and around the Bay this summer:

Why Is Vibrio on the Rise?

Cases in Maryland and Virginia have been on the rise in recent years.

Above other factors, Vibrio vulnificus thrives in warmer waters—making August a prime time to be on the lookout in and near the Chesapeake Bay.

“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.”

“This strain also thrives in lower oxygen conditions—another byproduct of warming water that might contain excess nutrient runoff.”

How Can Pollution Reduction Efforts Help?

Though warming waters are a primary driver, Vibrio often thrives in nutrient-rich environments—reinforcing the need for work to cut excess runoff and nutrient pollution flowing into the Bay.

“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,” said Chesapeake Bay Foundation Virginia Science Manager Mike Gerel.

Restoration work can help mitigate the threat. Streamside buffers, for example, filter pollution and shade headwater streams, keeping water cooler as it flows to larger tributaries.

How Can We Avoid Vibrio?

About 80,000 cases of vibriosis happen each year in the United States, according to the Centers for Disease Control and Prevention (CDC)—about 52,000 of which are the result of eating contaminated food.

“Statistically speaking, driving to the beach is riskier than spending time in the water,” Maguire said.

Still, there are certainly steps people can take to try to mitigate threats from Vibrio and the possibility of infection.

People should avoid swimming with open wounds and should always shower after swimming in natural or open waters, according to the Maryland Department of the Environment.

To minimize threats from Vibrio and other bacteria, people can avoid swimming in natural waterways for 48 hours after a major rainfall event.

They can also check out the National Oceanic and Atmospheric Administration’s (NOAA) Vibrio vulnificus risk map for the Bay.

The majority of cases in the U.S. are foodborne, so be smart about preparing and eating properly stored, treated, and cooked shellfish and oysters.

Raw oysters are a classic Bay delicacy and there is ample testing and regulation in the seafood industry to ensure that no bacteria is present in seafood products. If people want to err on the side of caution, especially during the hot summer months, they can experiment with new recipes that involve cooked oysters.

“Enjoy the Bay, enjoy your local waterways, and enjoy your oysters this summer,” Maguire said. “But be smart.”