A dangerous summer visitor is thriving in the Chesapeake Bay, prompting Maryland doctors to warn swimmers, crabbers and anglers about a potentially devastating bacterial infection. Vibrio cases are rising as bay waters warm, and the most severe infections can destroy tissue, trigger sepsis and become fatal with alarming speed. The good news is that a few basic precautions can sharply reduce the risk.
WBAL-TV 11 Baltimore reported Wednesday that Maryland health authorities have treated 72 people for a fast-spreading soft-tissue infection this year. Eleven people reportedly died from the bacteria in 2025, although no deaths have been reported in Maryland so far this year. Dr. Geetika Sood described Vibrio infection as a “very serious infection,” particularly when it reaches broken skin.
Vibrio bacteria occur naturally in coastal and brackish water, so this is not a sign that the Chesapeake Bay is suddenly contaminated. The Maryland Department of the Environment says the bacteria are more common during summer and early fall, when water temperatures are warmer, and that recreational transmission in Maryland waters remains relatively rare.
Warm Bay Water Creates A Seasonal Health Risk
A 2025 University of Maryland-led study found potentially pathogenic Vibrio strains in Chesapeake Bay samples collected across two separate three-year periods. The researchers said the mid- and lower-Bay areas, which include popular recreational and commercial waters, may carry greater risk for severe wound-associated infections. That does not mean every swim is dangerous, but it does make cuts and scrapes a particularly bad match for warm brackish water.
People with chronic liver disease, diabetes, iron-overload disease or weakened immune systems face a higher risk of severe illness, according to the Maryland Department of Health. Warning signs after water exposure can include rapidly increasing redness, swelling, pain or blood-colored blisters around a cut, along with fever. After eating raw or undercooked seafood, symptoms can include nausea, vomiting, diarrhea, stomach pain and signs of bloodstream infection.
How Chesapeake Bay Visitors Can Lower Their Risk
The “flesh-eating” nickname refers to the tissue damage that can occur in severe Vibrio vulnificus infections, not to every case of vibriosis. The Centers for Disease Control and Prevention says about one in five people with V. vulnificus infection die, and some patients require intensive care or amputation.
Doctors advise staying out of the Bay if you have an open wound, or covering it completely with a waterproof bandage if water contact cannot be avoided. Wear shoes when wading, use gloves when handling crab pots or equipment, shower after swimming in natural water and wash any cut immediately with soap and clean water. Anyone who develops a rapidly worsening wound or fever after Chesapeake Bay exposure should seek medical care right away and mention the water contact.
