Patty Konietzky thought the small purple lesion on her husband's ankle was a spider bite. But when the lesion quickly spread across his body like a constellation, she knew something wasn't right.

After a trip to the hospital and a day and a half later, Konietzky's 59-year-old husband was dead.

The diagnosis: vibrio vulnificus, an infection caused by a bacterium found in warm salt water. It's in the same family of bacterium that causes cholera. So far this year, 31 people across Florida have been infected by the severe strain of vibrio, and 10 have died.

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State health officials say there are two ways to contract the disease: by eating raw, tainted shellfish - usually oysters - or when an open wound comes in contact with bacteria in warm seawater.