At least six people have died on the East Coast this summer after being infected with "flesh-eating" bacteria in warming waters.
The U.S typically sees a handful of deaths in Gulf states, but it's rare for deaths to be spiking in East Coast states.
In response, the Centers for Disease Control and Prevention issued a health advisory to warn doctors, laboratories and public health departments to be on the lookout for these infections.
"The sky is not falling, but be careful, pay attention and take it seriously if you have an infection and get it treated," Dr. Rita Colwell, a microbiologist and marine expert at the University of Maryland at College Park and at Johns Hopkins University Bloomberg School of Public Health, told ABC News.
Vibrio bacteria cause an estimated 80,000 illnesses each year in the U.S., according to the CDC.
In particular, Vibrio vulnificus can lead to life-threatening infections. Between 150 and 200 infections are reported to the CDC every year with about one in five people dying -- often within a day or two of becoming ill, the agency said.
These bacteria are naturally occurring in saltwater and brackish waters and more abundant in the summer months, between May and October.
"Most often than not, this bacterium is going to have a coastal origin, meaning that somebody would visit coastal waters for recreation, they may have a wound or like exposed skin," Dr. Antarpreet Jutla, an associate professor in the department of environmental engineering science at the University of Florida, told ABC News. "And then these bacteria basically get into those holes and then a person can get infected."
Eating raw or undercooked shellfish such as oysters that live in coastal waters can also increase the risk of an infection caused by Vibrio vulnificus.
Symptoms of Vibrio vulnificus infection can include fever, nausea, vomiting, stomach cramps and watery diarrhea.
For those who have a bloodstream infection, symptoms include fever, chills, low blood pressure and blistering skin lesions, For a wound infection, a patient might have redness, pan, swelling, warmth, fever discoloration, and discharge.
Those with wound infections can suffer necrotizing fasciitis, which is when the flesh around an open wound dies. Treatment involves antibiotics and replacing liquids lost through diarrhea. Necrotizing fasciitis can sometimes lead to limb amputation.
Many of the infections in Connecticut, New York and North Carolina were contracted due to open wounds that were exposed to coastal waters, according to the CDC. Some of the infections were due consuming of raw or undercooked seafood -- and other infections had unclear origins.
To reduce the risk, health officials recommend people stay out of saltwater and brackish water if they have an open wound. If an open wound does come into contact with this water, wash the wound thoroughly with clean, running water and soap. Additionally, avoid eating or coming into contact with raw shellfish.
"If you got cut and it's healed over, that's not a problem," Tessa Getchis, an extension educator with Connecticut Sea Grant & University of Connecticut Extension, told ABC News. "If it's an open wound, they want to wait until that wound is closed."
She added that it's not enough to cover the wound with a waterproof bandage and that people with open wounds should avoid the water completely.
Jutla said that with more populations settling along the coasts and warming temperatures making coastal waters warmer for longer, it could be an issue in the future.
He and a team of researchers at the University of Florida sampled water in the Fort Myers region after Hurricane Ian in 2020 and found "extensive sampling" of Vibrio vulnificus, even after four weeks of sampling.
With the recent passing of Hurricane Idalia in southern states, experts say that floodwaters and storm surges may leave an opportunity for people to become infected with Vibrio vulnificus.
"If I were in that region, I would not wander around in flooded waters," Jutla said. "I would be very careful in in in going to sea water coastal waters ."