The widow of a Florida man who died from a gruesome infection says the seawater bacterium "creeped through his body like acid."

Henry "Butch" Konietzky, 59, is believed to have contracted vibrio vulnificus while crabbing along Central Florida's Intracoastal Waterway with his wife, Patty. The microscopic bug, which belongs to the same family as cholera, lurks in murky seawater along the Gulf Coast.

"I never heard there was even a bacteria in the water," said Patty Konietzky, recalling how her husband thought he'd been bit by a spider before heading to bed. He woke up hours later with pain coursing through his legs. "He felt like there was some sort of burn on his ankle."

By the morning, Konietzky had lesions all over his body. And within 28 hours after arriving at the hospital, he was dead.

"He has never been diagnosed with anything ever," Patty Konietzky said of her once healthy husband, calling the fatal infection "the most horrific thing I had seen in my life."

Vibrio vulnificus can cause vomiting, diarrhea and abdominal pain if ingested through contaminated seafood, according to the U.S. Centers for Disease Control and Prevention. But the bacterium can also invade open wounds and infect the blood in people with compromised immune systems, causing fever and chills, septic shock and blistering skin lesions.

Blood infections caused by vibrio vulnificus are fatal about 50 percent of the time, according to the CDC.

"It is extremely rare that someone without any medical problems - the picture of health - to get this infection and die," said ABC News' chief health and medical editor Dr. Richard Besser.

Henry Konietzky is the 27th Floridian to contract vibrio vulnificus this year and the ninth person to die, health officials told ABCNews.com.

"I can't imagine going day by day without him," Patty Konietzky said.

The CDC recommends the following precautions to avoid vibrio vulnificus infections:

Avoid eating raw shellfish

Cook shellfish thoroughly

Avoid food contamination with juices from raw seafood

Wear protective clothing when handling raw shellfish

Eat shellfish promptly after cooking and refrigerate leftovers

Avoid exposing open wounds to warm saltwater, brackish water or to raw shellfish