A flesh-eating bacterium is occurring more often in Delaware Bay crabs and shellfish as climate change warms ocean waters, exposing people with compromised immune systems to an increased risk of grievous injuries or even death, a South Jersey health system warned on Monday.
Cooper University Health Care said it treated five patients over the last two summers with “necrotizing fascitis” — which kills an area of flesh between the skin and the muscle — as a result of becoming infected with Vibrio vulnificus, a bug that lives in warm brackish waters. One patient died, one had his hands and feet amputated, and the others had areas of their flesh removed by surgeons to prevent the infection spreading.
“You can think of it as the most severe soft-tissue infection you could have,” said Dr. Katherine Doktor, a Cooper physician and co-author of an academic paper on the increased incidence of the infection.
While it is highly unlikely to affect healthy people who don’t have underlying illnesses and cases remain rare, Cooper’s health experts said the five cases over the summers of 2017 and 2018 represent a sharp increase from the single case that they treated in the previous eight years.
They described the infections in the latest issue of the medical journal Annals of Internal Medicine with the intention of alerting other doctors to watch for cases as the summer season gets underway.
Connection to climate change?
The increased incidence appears to be the result of the rising temperature of the Delaware Bay in response to climate change, Cooper officials said. While Vibrio vulnificus is common in the warmer waters of the southeastern United States, and is sometimes found in the Chesapeake Bay, it has been rare in the colder waters of the Delaware Bay, but that may be changing.
“Given that there’s a lot of scientific data showing the sea-water temperature is increasing, could it be that this bacteria, that likes to grow in warm water, is now in more northern areas because of climate change?” said Dr. Doktor.
She acknowledged that attribution to climate change is a hypothesis rather than a proven causal link, but said the evidence looked strong enough to issue a warning for other physicians and the public.
Researchers at the University of Bath in England concluded in a 2010 paper that warming waters are causing an increase in the number of illnesses related to Vibrio vulnificus, and that more can be expected.
“Climate anomalies have already greatly expanded the risk area and season for vibrio illnesses and suggest that these events can be forecasted,” the researchers said.
According to the New Jersey Department of Health, a Vibrio infection that gets into the bloodstream is fatal in about 50 percent of cases.
Underlying health conditions
Each of the patients treated by Cooper had underlying health conditions including hepatitis, diabetes, morbid obesity, and Parkinson’s disease, and so were much more susceptible to the infection than normal healthy people, Dr. Doktor said.
They all ate or handled crabs from the bay in the days before presenting symptoms that included swelling, blistering and pain in their arms and legs. Subsequent tests found all the patients had the infection in their blood.
One, a 60-year-old man with Parkinson’s was admitted with severe swelling in one leg, and later had both hands and feet removed by surgeons after they became “necrotic” — meaning the cells died — and threatened to infect the rest of his body, Cooper said.
That patient ate a dozen crabs the day before admission to the hospital and had been crabbing in the bay multiple times in the week before. Doctors said he didn’t immediately report his symptoms, and the delay may have caused the severity of his infection. He survived.
The patient who died, a 64-year-old man with untreated hepatitis C, presented with rapidly worsening pain and swelling in his right hand two days after cleaning and eating crabs caught in the bay, the paper said. Surgeons removed areas of infected flesh three times, but the patient later died from ventricular tachycardia, an abnormally fast heart rate.
How the infection is carried
In the bay, the infection can also be carried by other marine creatures that filter water, such as oysters, clams and mussels, and those are of particular concern if they are eaten raw, Dr. Doktor said. “If they were digging for clams and cut their hand on a clam shell, that could definitely have been a portal of entry for the infection,” she said.
The fact that all five patients had come into contact with crabs rather than the other potentially infected sea creatures was “kind of a coincidence” that may be explained by the popularity of crabbing on the Delaware Bay, she said.
Despite the gruesome experience of the five patients in the Cooper study, people without underlying illnesses such as hepatitis or diabetes are highly unlikely to get infected with Vibrio vulnificus as a result of coming into contact with Delaware Bay water, Dr. Doktor said.
“The likelihood of them getting sick is extraordinarily low,” she said.
But she warned that anyone who has those risk factors and cuts him or herself while out in the bay, should be aware that they are at risk, and so should seek immediate medical attention if a wound becomes painful, red and swollen.
“Wound infections occur through breaks in the skin, and intestinal infections occur after consumption of seafood. Either route can lead to bloodstream infections, and the mortality rate is high,” Cooper said in a statement.
No long-term effects in most cases
The New Jersey Department of Health has received reports of 20 cases of Vibrio so far this year, but they include other species of the bacterium, not just the vulnificus strain, and there is not yet a breakdown of the different kinds reported, said Nicole Kirgan, a spokeswoman for the agency. Most cases are associated with the consumption of shellfish. (The CDC says there are about a dozen species of Vibrio that can cause human illness.)
Between 2008 and 2018, the department received between 17 to 83 of Vibrio cases a year, up to four of which were fatal each year, she said. The number of Vibrio cases has been increasing in recent years but some of that is the result of changes in how the federal Centers for Disease Control and Prevention defines cases, she said.
The vast majority of cases occur in the summer because warmer temperatures allow the bacteria to multiply then, Kirgan said. In most cases, the symptoms resolve themselves without long-term effects. Officials believe Vibrio infections in general are under-reported. Nationally, there are about 80,000 cases of all types of Vibrio a year.
To avoid the risk of Vibrio infection, the department urged people to thoroughly cook shellfish before eating.