ST. PETERSBURG, Fla. — Patty Konietzky thought the small purple lesion on her husband’s ankle was a spider bite. But when it quickly spread across his body like a constellation, she knew something wasn’t right.
After a trip to the hospital, 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 is 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.
‘‘I thought the doctors would treat him with antibiotics and we’d go home,’’ said Konietzky, who lives in Palm Coast, Fla. ‘‘Never in a million years [did it cross] my mind that this is where I’d be today.’’
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.
In Mobile, Ala., this week health department officials said two men with underlying health conditions were diagnosed with vibrio vulnificus in recent weeks. One of the men died in September and the other is hospitalized. Both men were tending to crab traps when they came into contact with seawater.
While such occurrences could potentially concern officials in states with hundreds of miles of coastline and economies largely dependent on ocean-related tourism, experts say the bacteria is nothing most people should worry about. Vibrio bacteria exist normally in salt water and generally only affect people with compromised immune systems, they say. Symptoms include vomiting, diarrhea, and abdominal pain. If the bacteria get into the bloodstream, they provoke symptoms including fever and chills, decreased blood pressure, and blistering skin wounds.
But there’s no need to stop swimming in the Gulf of Mexico, says Diane Holm, a spokeswoman for the state health department in Lee County, which has had a handful of cases that included one fatality this year.
‘‘This is nothing abnormal,’’ she said. ‘‘We don’t believe there is any greater risk for someone to swim in the Gulf today than there was yesterday or 10 years ago.’’
There have been reports this year in Gulf states of other waterborne illnesses, but they are rare. In fresh water, the Naegleria fowleri amoeba usually feeds on bacteria in the sediment of warm lakes and rivers. If it gets high up in the nose, it can get into the brain. Fatalities have been reported in Louisiana, Arkansas, and in Florida, including the August death of a boy in the southwestern part of the state who contracted the amoeba while knee boarding in a water-filled ditch.
Dr. James Oliver, a professor of biology at the University of North Carolina in Charlotte, has studied vibrio vulnificus for decades. He said that while Florida has the most cases of vibrio infection due to the warm ocean water that surrounds the state, the bacteria is found worldwide, generally in estuaries and near the coast.
The vast majority of people who are exposed to the bacteria don’t get sick, he said. A few people become ill but recover. Only a fraction of people are violently ill and fewer still die; Oliver said many of those people ingest tainted, raw shellfish.
Oliver and Florida Department of Health officials say people shouldn’t be afraid of going into Florida’s waters, but that those with suppressed immune systems, such as people who have cancer, diabetes, or cirrhosis of the liver, should be aware of the potential hazards of vibrio vulnificus, especially if they have an open wound.