A rapidly fatal pathogen is moving up the coast: Know the signs
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ER docs and infectious disease docs have to remind ourselves about what Vibrio vulnificus looks like and how we treat it.
—William Schaffner, MD
As coastal waters warm, disease-causing non-cholera Vibrio bacteria are expanding northward and infecting people in more US states.[]
Clinicians should be aware that certain patients are at higher risk of severe or fatal outcomes from this preventable illness.
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The bacterial species Vibrio vulnificus can cause foodborne illness and serious wound infections. Cases are fatal in about 1 in 5 people. [] []
Other Vibrio species, including Vibrio parahaemolyticus and Vibrio alginolyticus, can also cause foodborne illness. These species are distinct from Vibrio cholerae, which causes cholera.[]
Increasing geographic range
William Schaffner, MD, professor of preventive medicine at Vanderbilt University Medical Center, explains that Vibrio bacteria are a natural component of brackish-water coastal ecosystems but have spread beyond their previous range.
“If we had been talking 10 years ago, we’d be talking about the Gulf Coast and its brackish waters offshore. In the last 10 years, Vibrio vulnificus made its way around Florida and is working its way up the Eastern Seaboard, causing illnesses in places like Massachusetts, where it was unheard of before,” Dr. Schaffner tells MDLinx.
Cases have been reported in other states, including Connecticut, New York, and North Carolina. [] Most cases occur between May and October, but infection can occur during the colder months.
“We think that global warming and the changing of the ecology along the Eastern Seaboard have changed the permissive environment so that the Vibrio vulnificus bacteria can now begin to flourish farther north,” Dr. Schaffner says.
Foodborne vibriosis
Raw or undercooked oysters are the most common source of foodborne vibriosis, as oysters are filter-feeders. As a result, Vibrio concentrations within oysters may be 100 times greater than those in surrounding waters. []
In healthy individuals, ingestion of Vibrio bacteria from oysters or other raw seafood can cause gastroenteritis, but this is usually mild and self-limited.
However, Dr. Schaffner explains, “V. vulnificus is not a problem to the average person. Most people who become ill with V. vulnificus after eating raw oysters have distinct immune deficiencies or liver disease.”
In these individuals, he says, “V. vulnificus can leave the intestinal tract, get into the bloodstream, and cause very serious, life-threatening sepsis.”
Members of these high-risk groups should thoroughly cook all seafood to kill Vibrio bacteria.
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The risk factors for wound infections differ and are associated with working or spending time on the water, Dr. Schaffner explains.
“The majority of those who develop necrotizing fasciitis from V. vulnificus are not immune-compromised; they are healthy people who are out on the water—they have broken skin, or they get injured, and the wound gets contaminated with Vibrio vulnificus," he says.
V. vulnificus wound infections must be identified and treated promptly in collaboration with a surgeon, as V. vulnificus infections can progress rapidly and sometimes cause death within 1–2 days. [] Patients often require intensive care, including wound debridement or limb amputations.
People with open wounds or cuts should avoid direct contact with brackish water. Workers who handle raw shellfish are also at risk.