Health officials in Florida are warning beachgoers of the risk of flesh-eating bacteria, reports Fox News. The bacterium, called Vibrio vulnificus, is a naturally occurring bacterium that thrives in warm, moderately salty water. It can be particularly dangerous for individuals that have a weak immune system and, once it gets into the bloodstream, is 50 percent likely to be fatal.

According to ABC 3 WEAR, the bacteria invade cuts and scrapes to cause flesh-eating disease. The “flesh-eating” nature of the disease is to cause skin breakdown and ulceration. The bacteria can also cause stomach pain, vomiting, and diarrhea. Any direct contact with seawater through an open wound can lead to contracting the bacteria.

The U.S. Centers for Disease Control and Prevention (CDC) explain that Vibrio vulnificus is a bacterium in the same family as the one that causes cholera. For healthy people, the result of infection is likely gastrointestinal, while it is more likely to enter the bloodstream for immunocompromised individuals. Once it is in the bloodstream, fatal complications are more likely, leading to the fatality rate.

Thus far this year, there have been 11 Floridians that have contracted an infection and two have died. Last year, 41 people were infected and 11 died in Florida. Outside of Florida, there have also been cases of infection, including a 2013 outbreak linked to contaminated shellfish. That outbreak sickened at least 104 people in 13 states.