Prior to last year, New Jersey’s Cooper University Hospital had only seen one case of Vibrio vulnificus, a flesh-eating bacterial infection linked with eating or handling contaminated shellfish, over the course of the previous eight years. But in 2017 and 2018, five patients afflicted with the infection sought treatment at the hospital, leading staff to wonder why the bacteria, which typically thrive in the warmer waters of the southeastern United States coast, were becoming increasingly common in regions outside of their traditional geographic boundaries.

A new study published in the journal Annals of Internal Medicine implicates a potential culprit in V. vulnificus’ spread: climate change, as evidenced by rising temperatures in previously cooler bodies of water like the Delaware Bay.

Typically, the destructive bacteria thrive in slightly salty brackish waters with surface temperatures above 13 degrees Celsius, or 55.4 degrees Fahrenheit. Per CBS News’ Caitlin O’Kane, such conditions are often found in the Gulf of Mexico, along southern states including Texas and Louisiana, and south of the Chesapeake Bay. The Delaware Bay, bordering southern New Jersey and Delaware, has long been considered too cold for V. vulnificus, but as the team of infectious disease specialists and clinical pharmacists writes in the study, the strain appears to be on the move, with warmer temperatures facilitating changes in the “quantity, distribution and seasonal windows of bacteria.”

According to Sara Chodosh of Popular Science, V. vulnificus is one of about a dozen species known to cause vibriosis, an infection that affects some 80,000 people every year. (Of these, around 100 annually eventually die from the infection.)

In most instances, the illness—contracted by eating raw or undercooked shellfish, particularly oysters, or handling infected marine creatures while sporting an open wound—manifests as diarrhea- and vomit-filled food poisoning. In more serious cases, Julia Hatmaker writes for Penn Live, bacteria enter the bloodstream, making ulcers, black spots and pus emerge around the infected area. Although antibiotics can help slow the spread of infection, skin grafting, skin removal and even amputation may be necessary to restore patients’ health.

As CNN’s Susan Scutti reports, four of the five individuals (all men) featured in the study eventually made full recoveries. But one, a 64-year-old who sought treatment two days after cleaning and eating Delaware Bay crabs, arrived at the hospital with a swollen right hand and died during doctors’ third attempt to remove all of his dead and dying skin.

Among the remaining patients were a 38-year-old who hadn’t ventured near the Delaware Bay but worked at a New Jersey restaurant serving seafood, a 46-year-old who injured his left leg while crabbing in the bay, a 64-year-old who slashed his leg open on a crab trap, and a 60-year-old whose “mummified” arms and legs had to be at least partially amputated.

“The infection courses through the entire body, kind of like a hurricane or tornado that ravages everything,” study co-author Katherine Doktor tells Business Insider’s Aylin Woodward.

Popular Science’s Chodosh writes that it’s worth noting the cases in question are “unusually severe.” All five patients had underlying risk factors, including hepatitis, liver disease and diabetes, known to exacerbate vibriosis; according to the Centers for Disease Control and Prevention, those with healthy immune systems usually escape the worst of the infection.

To lower one’s chances of contracting vibriosis, the CDC recommends not eating raw or undercooked shellfish and covering open wounds with waterproof bandages.

Speaking with CNN’s Scutti, Doktor adds, “Anyone with cuts, sores or broken skin or with immunocompromised conditions who notice changes or the appearance of infection after spending time in the water (particularly brackish waters) should seek medical attention promptly as early medical [intervention] is key to the best outcomes.”

The study’s authors write that they hope the report alerts clinicians in the Delaware Bay area to watch out for V. vulnificus infections, as they are “occurring more frequently outside traditional geographic areas.”

At the same time, Doktor tells Business Insider’s Woodward, the team warns that vibriosis isn’t the only infectious disease at risk of spreading due to global warming. Diseases like Zika virus and dengue fever could threaten nearly 500 million more people by 2050, according to a study published in March.

She concludes, “We're concerned about infections that were once considered only tropical could now occur at warmer latitudes.”