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Study: Increased number of carnivorous bacteria in Delaware Bay, possible effect of climate change

New research suggests that climate change can lead to unlikely diseases in unexpected places: In the last two years, five cases of Vibrio vulnificus, a flesh-eating bacterial infection transmitted through the handling or consumption of contaminated seafood, have been linked to Delaware Bay, where water temperatures have risen in recent years, according to a study.

These five patients were treated at a New Jersey hospital and serve as a warning that bacterial eroding infections are now occurring outside of traditional geographic boundaries, the authors said.

"It is important that physicians – who may have never seen this infection before in their medical practice – be made aware," co-authored Dr. Katherine Doktor, infectious disease specialist at Cooper University Health Care. , in an email. .

Prior to 2017, Cooper University Hospital in Camden, New Jersey, had only known one serious case of Vibrio infection in eight years, explained Doktor, also an assistant professor at the Cooper Medical School of Rowan University. In just two years, the hospital saw and treated five patients, one of whom died.

Favorable conditions for bacteria

"Significant increases in sea surface temperature" have occurred over the last three decades in many parts of the United States, noted the study published Monday in the journal Annals of Internal Medicine. Warmer temperatures have resulted in changes in "the amount, distribution and seasonal windows of bacteria" in the coastal ecosystem, while creating "more favorable conditions for Vibrio," said Doktor.

Although Vibrio is endemic off the coast of Virginia and Maryland in Chesapeake Bay, as well as in the southern waters of the United States, these diseases rarely occur in the cooler Delaware Bay, whose waters splash south of New Jersey.

"Although infection is still rare, it is seen more frequently in this region," said Doktor.

The five patients who received treatment at Cooper University Hospital, New Jersey, illustrate this changing reality:

A 38-year-old man arrived at the hospital vomiting, with a fever and rash on his soft left calf. His blood cultures confirmed Vibrio, already evident by his dying skin. Although he was not near Delaware Bay, he was working in a New Jersey restaurant that probably served seafood from the bay. A successful treatment, which included skin grafts, led to his discharge from the hospital.

The second patient, a 64-year-old man, sought medical attention two days after cleaning and eating Delaware Bay crabs. His right hand had begun to swell. After checking Vibrio, his doctors removed portions of deep connective tissue. At a third attempt to eliminate all the dead and dying skin, the patient's heartbeat became irregular and he died.

A third man, aged 46, appeared at the Cooper University Hospital to complain of a swollen left leg two days after being crab injured in Delaware Bay. Skin and blood cultures confirmed Vibrio infection. Vesicles on his calf caused the doctors to remove the connective tissue and perform transplants.

Arrived at the hospital with a severely swollen right leg, a 60-year-old man suffered shock followed by respiratory failure. He had cracked in Delaware Bay and prepared a dozen crabs. Excessive coagulation blocked his small blood vessels and his four limbs became "mummified" and therefore required amputation, wrote the study's authors. His late arrival at the hospital caused the severity of his Vibrio infection.

The last patient, a 64-year-old man, had cut his right leg to a Delaware Bay crab trap before appearing at Cooper University Hospital. Haemorrhagic lesions on his right arm caused a shock. The hospital confirmed Vibrio and removed the tissue dying.

"In all the cases we saw, patients had known risk factors (liver disease, diabetes or other immune deficiency) when a skin lesion was exposed to water and / or [when the patient] consumed uncooked molluscs harvested from Delaware Bay, "wrote Doktor.

Who is at risk for Vibrio

Dr. Stephen Spann, Dean of the Faculty of Medicine at the University of Houston, said it was difficult to "convincingly prove" that flesh-eating bacteria were heading north because of global warming, according to only five patients.

"It's suggestive, is not it?" Spann asked, who was not involved in the research. He added that it is "hard to say that all of this is due to climate change – although it could very well be".

Another factor that influences the presence of Vibrio vulnificus is the salinity of water. "When the salinity or salt content of these waters decreases, the concentration of Vibrio increases," he explained. Other circumstances, including the presence of pollution, can affect the bacterial concentration.

However, people need to know that "this is a problem," said Spann. "You hear about cases, but it's not like an epidemic." This is true even in areas surrounding much warmer Texan waters, where flesh-eating bacterial infections are more common but not "super common".

Since 2010, between 700 and 1,200 cases occur each year in the United States, but this is likely to be an underestimate, according to US Centers for Disease Control and Prevention.

Having a wound exposed to the brackish water where these bacteria live is a means of contracting an infection; eating contaminated molluscs – "oysters, mainly" – is another, he said. "Certainly, people in this area would benefit from paying attention to that."

"Your healthy person probably does not pose a huge risk," said Spann, noting that vulnerable people include "people with a chronic disease that weakens their immune function, or who may be taking drugs. Immunosuppressive drugs such as corticosteroids, liver disease or a condition called hemochromatosis, which is an iron storage disease where there is not enough iron in the body.

One way to stay safe is to cook the mollusks well before eating them, said Spann.

Doktor nodded, adding, "Anyone with cuts, wounds, broken skin or immunocompromised diseases who notice changes or infection after spending time in the water (especially brackish water) should seek immediate medical attention. (early medical intervention) the best results. "

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