Flesh-Eating Bacteria Is Infecting More People And Spreading To New Areas. Scientists Blame Climate Change.
“We’re seeing Vibrio infections actually in areas that we’ve never seen before.”
The morning after a deep-sea fishing trip off of Florida’s Gulf Coast, Brielle Owens got out of bed and immediately fell to the ground.
“I literally just could not walk,” said Owens, who was 25 at the time. “It felt as if I had no feeling in [my left] foot. It was just limp.”
Her parents rushed her to the emergency room where doctors took a culture of a pimplelike bump on her ankle, then sent her home with some antibiotics. Days later, a surgeon was cutting out dead tissue from her foot. Over the course of several weeks, tissue had to be removed two more times.
“They told me that if they had to do another surgery that they were most likely going to have to cut my leg off,” Owens said.
What her doctors initially believed was a spider bite rapidly progressed into a severe skin infection caused by a rare but deadly form of Vibrio, a group of bacteria naturally found in warm, brackish, and ocean waters all over the world. People can become infected by eating contaminated seafood, particularly raw oysters, or exposing cuts or breaks in the skin to water containing the bacteria — which can lead to what’s commonly referred to as flesh-eating disease.
In the US, the number of reported cases of Vibrio illness has more than tripled since 1997, from 386 to 1,256 in 2016, according to the Centers for Disease Control and Prevention. Now experts say climate change is helping drive the increase, allowing the bacteria to thrive in areas that were previously too cold, and illustrating one of the many unforeseen threats rising temperatures and sea levels pose to human health.
This summer, hundreds of cases of Vibrio have been reported up and down the Atlantic Coast, across the Gulf states, and in the Pacific Northwest, according to CDC data. Several people have died from the infections in Texas and Florida.
The increase in illnesses comes as climate change and coastal urbanization create a perfect storm for waterborne bacteria, said Geoff Scott, clinical professor and chair of the department of environmental health sciences in the Arnold School of Public Health at the University of South Carolina.
“You get increased runoff of nutrients, increased levels of other things in the water, plus the rise of sea level, the change in temperature and salinity — those are all factors that can make these Vibrio bacteria have a very unique opportunity,” Scott told BuzzFeed News.
The CDC estimates that the bacteria cause 80,000 illnesses and 100 deaths each year, with the majority occurring between May and October when water temperatures are warmer. About a dozen species of Vibrio can cause human illness, but the most common in the US are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus.
Reported cases of Vibrio parahaemolyticus and Vibrio vulnificus.
Vibrio bacteria can cause a range of illnesses from gastroenteritis — a disease marked by diarrhea, abdominal cramping, nausea, vomiting, fever, and chills — to septicemia, a life-threatening bloodstream infection. Vibrio vulnificus, the species most commonly associated with wound infections, can also cause necrotizing fasciitis, commonly referred to as flesh-eating disease, and lead to amputations and even death.
Anyone can get sick from Vibrio, but people with existing health conditions, like diabetes, liver disease, or cancer, are more likely to become ill and develop severe complications.
Erin Stokes, an epidemiologist in the CDC’s Enteric Diseases Branch, said the agency’s data shows the number of Vibrio infections have been increasing for many years, and while research is yet to clearly show why the increases are occurring, the warming of coastal waters is likely a factor. That’s because the bacteria proliferate in water temperatures above 15 degrees Celsius, or 59 degrees Fahrenheit, a threshold that’s being exceeded more often in waters farther north than previously seen.
“We’re seeing Vibrio infections actually in areas that we’ve never seen before,” Rachel Noble, professor of marine sciences at the University of North Carolina at Chapel Hill, told BuzzFeed News. “You’re talking about places in Norway, Finland, the Baltic Sea — very, very far north."
It’s possible for Vibrio to grow in waters colder than 15 degrees Celsius, said Noble, whose lab has been studying the bacteria for 20 years, but at and above that temperature the bacteria grow more plentifully and begin to pose a threat to human health.
Historically, Vibrio illnesses from seafood consumption in the US have been linked to shellfish from the Gulf of Mexico, where water temperatures are regularly warm, but in the last 20 years, outbreaks have been connected to shellfish harvested in the Pacific Northwest, Alaska, and parts of the Northeast.
“One of the major factors why we’re seeing more cases is the wider geographical expansion of the range so that more people are coming in contact with it,” Scott said.
And while the majority of illnesses — about 52,000 — are the result of eating contaminated food, skin infection cases are also occurring in areas where the bacteria were not previously endemic.
In a report published in the Annals of Internal Medicine in June, doctors at Cooper University Hospital in New Jersey linked climate change to a spike in severe skin infections in the Delaware Bay. Between 2017 and 2018, the hospital saw five patients with flesh-eating Vibrio vulnificus infections, one of whom died as a result.
In the previous eight years, the hospital had only seen one case of a Vibrio wound infection.
“We were surprised that we were seeing more wound infections caused by Vibrio this far north,” Dr. Katherine Doktor, one of the authors of the report, told BuzzFeed News.
Doktor, an infectious disease physician and assistant professor at Cooper Medical School of Rowan University, said while infections are common in the Chesapeake Bay farther to the south, it was unusual to see cases from the Delaware Bay, which is sandwiched between Delaware and New Jersey.
Rising sea surface temperatures in the Delaware Bay, they concluded, must have been a factor in the sharp increase in infections. Data from the National Oceanic Atmospheric Administration shows water temperatures at two sites in the estuary hovered in the mid-70s during the summers of 2017 and 2018, when the five patients were infected.
Though rare in comparison to other bacterial infections like staph, Vibrio vulnificus infections can progress rapidly and become fatal. About 1 in 5 people infected with the bacteria die, sometimes within a day or two of becoming ill, according to the CDC.
“We wanted people, health care providers specifically, to be aware that if they were to see a very severe infection that was spreading rapidly, they should consider Vibrio vulnificus as one of the causes,” Doktor said.
Other types of bacteria can also cause flesh-eating disease. Public health officials believe the bacteria that causes strep throat is the most common cause of the infection, according to the CDC.
“The key is, if you go swimming and you get an infection, it would probably be wise if it gets very red and inflamed ... to seek medical help early,” Scott said.
For wound infections, early antibiotic treatment and, if needed, surgery are the best way to prevent the disease from spreading. Still, experts emphasized that while the risk of exposure and the geographical range of the bacteria are expected to continue growing, healthy people have a lower chance of getting sick.
“I don’t want people to be afraid to go in the water or eat shellfish, but I do think that people who have these risk factors need to be conscious of them and, you know, adjust their eating habits and their activities,” Doktor said, adding that people should also avoid going in brackish or salt water if they have any open wounds.
And while not all strains of the disease-causing Vibrio species make people sick, it appears that the variants that cause illnesses have been showing up more frequently in recent years.
“Climate change is likely to be playing a role in the development of more dangerous Vibrios, meaning that the more pathogenic ones are becoming more numerous,” Noble said.
In addition to warming ocean temperatures, sea level rise is also contributing to the growth of Vibrio in estuaries by infusing salt water further into coastal rivers.
In a study published last year, Scott and other scientists predicted a significant expansion of the deadly bacteria in a South Carolina bay due to increases in salinity, resulting in a more than 200% increase in the risk of exposure to the bacteria.
“If that condition holds true in other parts of the world because of the increasing sea level rise and the expanding geographical range, then that means we’re going to see a lot more of those Vibrios in the future,” Scott told BuzzFeed News.
Urbanization of coastal areas is also contributing to the bacteria’s growth, including in historically warmer waters where Vibrio has long been found. As communities pour asphalt and concrete over coastal lands that would typically absorb rainfall, stormwater runoff sends more nutrients into streams, estuaries, and the ocean, causing a proliferation of algae that Vibrio thrive off of.
“The nutrients make the algae grow, the algae proliferates, and then you have a situation where the Vibrio, they literally take off,” Noble said.
The problem is exacerbated in the event of a hurricane, another naturally occurring phenomenon being driven to new extremes by climate change. Floodwaters from hurricanes often contain a range of harmful chemicals and microbial pathogens, including Vibrio bacteria.
In Louisiana after Hurricane Katrina, the CDC reported two dozen cases of Vibrio wound infections leading to six deaths. Cases of flesh-eating disease were also reported in the wake of Hurricane Harvey in 2017, and Noble said she heard anecdotally from emergency room physicians in North Carolina that they saw upticks in infections after hurricanes Matthew and Florence.
Scientists are working to develop better forecasting models to predict and ultimately warn the public when Vibrio outbreaks could occur. While measures are in place to try to minimize the risk of illness from seafood consumption, there aren’t any beach testing programs or advisories to prevent infections from recreational contact.
Unlike with E. coli and blue-green algae toxins, there is no threshold for Vibrio that would indicate risk of illness.
Owens grew up fishing, snorkeling, and playing water sports along the Gulf Coast, but hadn’t heard much about bacterial infections before she got sick in 2017.
“Until it actually happened to me, I honestly only heard of maybe a few cases, but I feel like now I hear of them almost every single week,” the 27-year-old said.
Realizing that she had been infected with a bacteria that could have killed her in the waters she had enjoyed all her life was shocking.
“It makes you question everything,” said Owens, who now lives in Charlotte, North Carolina.
Though the infection didn’t take her life, it certainly changed it.
Owens spent three to four months in the hospital that summer as doctors worked to rid her of the infection with surgery and antibiotics. The surgeries left about a foot-long, 3-inch-wide hole in her left leg.
“My wound nurse would have to stuff that full of gauze every day, wrap it, and then come back the following day and rip all of that out,” Owens said. “That was my life every single day for months.”
The experience cost Owens her job, triggered her anxiety and depression, and left a large, dark scar on her foot and leg.
These days Owens said she is sometimes hesitant about going in the water but tries to not let the fear of getting an infection control her life.
“I live and breathe the water,” she said, “but I do second-guess where I go in the water now.”