Health officials are warning visitors to Florida beaches about a rare, potentially deadly, bacteria that has infected seven and killed two so far this year.

A spokesperson for the Florida Health Department says Vibrio vulnificus thrives in warm waters and can spread through eating raw shellfish and direct contact with seawater for those with open wounds.

The counties where there have been confirmed cases of Vibrio in 2015 include Brevard (1 death), Broward, Duval, Marion (1 death), Pasco, Santa Rosa and St. Lucie.

According the the Centers for Disease Control, in healthy people the bacteria can cause vomiting, diarrhea, and abdominal pain. Those with weakened immune systems or liver disease are at risk of the bacteria entering the bloodstream, these bloodstream infections are fatal about 50% of the time.

Infections are most common between May and October and are rare, the Florida state health department said there have been 32 cases in the past 12 months.

The CDC says Vibrio vulnificus can be treated with antibiotics, but to avoid contracting an infection experts recommend not entering the water if you have fresh cuts or scrapes. People with a compromised immune system should take extra precautions by wearing proper foot protection to prevent cuts caused by rocks and shells on the beach.