Vibrio vulnificus is a rod-shaped bacterium of the genus Vibrio present in warm seawater. It causes an infection often incurred after eating seafood, especially shellfish. The bacteria can also enter the body through open wounds when swimming or wading. Symptoms include diarrhea and a blistering dermatitis that is sometimes mistaken for pemphigus or pemphigoid . Severe symptoms and even death can occur if the bacterium enters the bloodstream—something more common in people with compromised immune systems.

Theoretically, anyone can be infected by uncooked seafood. However, there are people who are especially vulnerable, including those with achlorhydria (decreased gastric acid production) and haemochromatosis.

When caught early, the infection can be treated with antibiotics. However, some people have had limbs amputated to stop the disease from spreading.

With the exception of oysters originating from the State of Mississippi, multiple deaths from V. vulnificus are reported in the U.S. states bordering the Gulf of Mexico each year.