Florida health officials have issued a startling warning just in time for summer; bathers should be wary of the rare and possibly deadly bacteria Vibrio vulnificus. According to the Orlando Sentinel, the bacteria occur in warm, brackish water and invade the bodies of swimmers through open wounds.

The Florida Department of Health reminded citizens “Water and wounds do not mix,” specifically recommending that people with fresh cuts or even scrapes should not enter the water whatsoever.

The agency warned that people with weakened immune systems as a result of chronic liver disease or kidney disease were at a particularly high risk of infection, and should take measures to avoid getting cut or scraped in the first place while at the beach.

The bacteria can also be found in seafood, particularly raw shellfish like oysters. If consumed directly, the bacteria are much more potent and could be deadly. There have already been seven cases of Vibrio infection this year in Florida, including two that resulted in fatalities.

Vibrio vulnificus causes an infection that results in vomiting, diarrhea, abdominal pain, and blistering skin. Infections through open wounds carry a mortality rate of 25 percent, whereas those with weakened immune systems face a mortality rate of 50 percent. There is currently no standard treatment for Vibrio vulnificus infection.

Cases typically occur between May and October, when the average water temperature is between 68 and 95 degrees.