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…