Five Dead in Louisiana From Coastal Water Bacterium

Five people have died in Louisiana this year from Vibrio vulnificus, a bacterium found in warm coastal waters, with the state recording nine cases against a ten-year average of seven cases and one death for the same period.

The Louisiana Department of Health reported the figures on Thursday. All nine patients were hospitalised.

How were the infections contracted?

Every case this year involved a wound exposed to seawater, and all patients had underlying health conditions, the department said.

The bacterium occurs naturally in warm brackish and salt water and reaches higher concentrations between May and October. Infection can also follow the eating of raw or undercooked shellfish, particularly oysters.

What is Vibrio vulnificus?

Vibrio vulnificus is a bacterium that occurs naturally in warm brackish and coastal salt water, and is the most severe of about a dozen Vibrio species that cause the illness known as vibriosis. Infection occurs when an open wound is exposed to seawater, or through eating raw or undercooked shellfish, particularly oysters. It can cause wound infections, gastrointestinal illness or bloodstream infection, and may require intensive care or amputation. According to the United States Centers for Disease Control and Prevention, about one in five people infected die, in some cases within one or two days. Concentrations are highest between May and October. As of 7 August 2026, the Louisiana Department of Health had recorded nine cases in the state during 2026, all requiring hospitalisation, of which five were fatal, against a ten-year average of seven cases and one death for the equivalent period.

Who is most at risk?

The health department lists people with liver disease, cancer, diabetes, HIV or thalassemia, those receiving immune-suppressing treatment, people taking medication that reduces stomach acid, and those who have recently had stomach surgery.

Officials advise staying out of brackish or salt water with an open wound, including cuts, scrapes, recent surgical wounds and piercings, and covering wounds with a waterproof dressing where contact is possible.

Symptoms of wound infection include fever, redness, pain, swelling, skin discolouration and discharge. Signs of bloodstream infection include fever, chills, very low blood pressure and blistering skin lesions.

Is this part of a wider pattern?

Florida has recorded two deaths this year, after 19 in 2024 and five in 2025. Officials there have linked higher infection rates to major storms that leave floodwater and standing water in communities, as after Hurricane Helene in 2024. Cases have also risen in Maryland.

Public health specialists attribute the spread into new regions to rising water temperatures. The bacterium was detected this spring in water samples off Long Island in New York, well north of its established range.

Why the season matters

Louisiana’s count has already passed its typical full-year average with two months of the warm-water season still to run. Concentrations of the bacterium peak through to October, so the figure is expected to rise further.

The infection is rare relative to its severity, which is what makes the case fatality rate the significant number. Nine cases is a small outbreak by any measure; five deaths from nine is not.

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