A rare, flesh-eating bacteria found in brackish seawater has killed five people in the Tampa Bay area this year. Now, health officials are warning Florida residents to stay vigilant when swimming in the state’s waters thanks to Vibrio vulnificus, a naturally occurring bacteria with some nasty symptoms. “Living in Florida, being around the marine environment, we need to be aware of what it is,” Dr. Eric Shamas, an emergency medicine physician at Bayfront Health St. Petersburg told local station WESH 2. The bacteria can enter a swimmer through open wounds, but it can also invade the body when eating raw shellfish—oysters, particularly. An infected patient can experience vomiting, diarrhea, abdominal pain, fevers, low blood pressure and even septic shock. Luckily, this year is on track to record fewer cases statewide than last year. This year, five people have died and 25 cases have been reported, according to WESH 2. Last year, 17 people died of 74 total cases.