The Vibrio vulnificus reference article from the English Wikipedia on 24-Apr-2004
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Vibrio vulnificus

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Vibrio vulnificus is a rod-shaped bacterium of the genus Vibrio. It causes an infection often incurred after eating seafood, especially shellfish. Symptoms include diarrhea and a blistering dermatitis that is sometimes mistaken for pemphigus or pemphigoid.

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