CDC: Deadly Vibrio Bacteria Killed Five People in Three States Last Summer

Over just 2 summer months last year, three Eastern states reported 11 cases of severe Vibrio vulnificus infections, of which five resulted in death, CDC researchers reported.

In July and August 2023, there were seven infections in North Carolina, two in New York, and two in Connecticut, Michael Hughes, MPH, of the CDC's National Center for Emerging and Zoonotic Infectious Diseases, and colleagues reported in the Morbidity & Mortality Weekly Report.

The cases were notable in that they occurred in the wake of record-breaking heat waves in the U.S., the researchers said.

"Although these cases reported during July-August cannot be solely attributed to the heat waves, the relationship between vibriosis incidence and environmental conditions favorable to Vibrio growth, namely elevated water surface temperatures and low salinity, is well-documented," they wrote.

Hughes and colleagues noted the swift response from the public health departments of these states, all of which issued press releases letting the public know about the infections, as well as the CDC, which issued a Health Advisory Notice.

That kind of quick action may be more necessary as V. vulnificus infections -- once largely limited to Gulf Coast states -- stand to expand their geographic range given environmental changes wrought by climate change, the researchers said.

"As coastal water temperatures increase, V. vulnificus infections are expected to become more common," Hughes and colleagues wrote. "Persons can take steps to prevent illness by avoiding wound contact with brackish water, salt water, and raw seafood, and by thoroughly cooking oysters and other seafood before eating."

Among last summer's cases from three states, the median patient age was 70 (range 37 to 84), and seven were men.

One patient was lost to follow-up, but among the 10 with complete information, all but one had at least one underlying condition -- most commonly diabetes, cancer, heart disease, history of alcoholism, and hematologic disease.

Four patients experienced septic shock and five died; three experienced septic shock and died, the researchers reported. All of the patients who died had at least one underlying condition.

Three of the North Carolina cases, two of the New York cases, and one Connecticut case involved exposure of a wound to the bacteria in a marine or estuarine environment, they reported. Two other North Carolina cases likely resulted from exposure to a cut on the hand while handling raw seafood.

One Connecticut case had foodborne exposure from oysters eaten in another state, and another North Carolina patient reported both wound exposure to brackish water and eating raw oysters.

While North Carolina reported 10 to 13 cases per year in 2021-2023, Connecticut reported no infections during all of 2021-2022 and New York had three cases in 2021 but none in 2022, the researchers said.

There were likely many other deaths due to V. vulnificus last summer, but there are no national data on such deaths. For instance, by August, Florida had reported five V. vulnificus deaths of its own.

There are many species in the Vibrio genus -- including V. cholerae, which causes cholera -- and they thrive in salt and brackish water. These bacteria cause an estimated 80,000 illnesses in the U.S. each year, according to the CDC. Most people have diarrhea, and some might also have stomach cramping, nausea, vomiting, fever, and chills.

But V. vulnificus is particularly pathogenic, especially if it gets into an open wound. It can enter through the smallest of skin lesions -- think piercings, tattoos, tiny cuts and scrapes -- and infections can very rapidly turn necrotic, according to a paper in Scientific Reports. Wound infection mortality rates are as high as 18% and fatalities have occurred as soon as 48 hours after exposure.

The CDC said there are currently about 150 to 200 V. vulnificus infections each year, and these are primarily skin infections; in about 10% of cases, this species can infect people if they eat raw or undercooked shellfish.

These wound infections have a short incubation period and are characterized by necrotizing skin and soft tissue infection, with or without hemorrhagic bullae, according to the CDC. Many people require intensive care or surgical tissue removal.

In its alert from last summer, CDC noted that "prompt treatment is crucial to reduce mortality from severe V. vulnificus infection." Early antibiotic therapy and early surgical intervention improve survival, CDC said: "Do not wait for consultation with an infectious disease specialist or laboratory confirmation of V. vulnificus infection to initiate treatment."

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