A deadly flesh-eating species of bacteria is spreading along the eastern coastline of the United States and could pose a growing threat. The bacteria, Vibrio vulnificus, causes an illness in humans called vibriosis, which can lead to life-threatening complications.
Most people become infected by exposing an open wound to contaminated seawater or consuming raw shellfish. In recent months, fatal infections have made headlines, spooking beachgoers and seafood-lovers alike.
Last week, a man in Texas died after eating raw oysters at a restaurant, Galveston County\u00a0health officials reported. Similar incidents have happened this year, including\u00a0one man from Missouri\u00a0who died in June.
Some experts are concerned that the bacteria, which thrives in warm coastal waters, is expanding geographically and could infect more people as water temperatures rise due to climate change.
Vibrio vulnificus infections are rare, especially in the Northeastern U.S., but recent reports of cases and deaths as far north as New England have ignited new warnings from health officials.
On Sep. 1,\u00a0the U.S. Centers for Disease Control and Prevention\u2002issued a health advisory about recent reports of severe vibrio vulnificus infections associated with warming coastal waters.
In July and August, the U.S. experienced above-average coastal sea temperatures and heat waves, per the CDC. During this same period, at least six deaths from vibrio infections were reported in three states along the East Coast.
NBC News reported\u00a0in August that a person in New York and two in Connecticut died from vibriosis associated with wound infections or consuming raw oysters.
Three people died this summer from vibrio in North Carolina, prompting state health officials to urge caution around swimming in saltwater or brackish water, according to\u00a0the North Carolina Department of Health and Human Services.
In Florida, where vibrio vulnificus is endemic, there have been 37 confirmed cases and eight deaths in 2023 so far, per\u00a0the Florida Department of Health.
There’s no need for the public to panic, according to experts, but it’s important to stay informed. What causes vibrio vulnificus, where is it found, and are cases and deaths actually on the rise?
What is vibrio vulnificus?
Vibrio vulnificus is a species in the vibrio group of bacteria, which lives in marine environments. The majority of vibrio strains are harmless, but about a dozen species can cause disease in humans, Salvador Almagro-Moreno, Ph.D., associate professor at the Burnett School of Biomedical Sciences at University of Central Florida, tells TODAY.com. According to the CDC, vibrio vulnificus is one of the most common strains in the U.S.
Vibrio vulnificus is sometimes called flesh-eating bacteria because an infection with it can cause flesh around an open wound to die. People become infected with vibrio vulnificus through exposing an open wound to saltwater or brackish water where the bacteria lives or through eating raw shellfish.
The bacteria are not a result of pollution. \u201cThey\u2019ve been there for millions of years. That\u2019s where they live \u2026 which makes the option of eradicating them impossible,\u201d says Almagro-Moreno, who directs a laboratory which researches the evolution of vibrio.
Where is vibrio vulnificus found?
Vibrio lives in coastal regions around the world. It thrives in warm saltwater or brackish water (a mixture of saltwater and fresh water). Brackish water can be found in estuaries, bays, lakes and ponds.
In the U.S., vibrio vulnificus is commonly found in waters near the Gulf Coast, in states such as in Florida, Texas and Louisiana, says Almagro-Moreno, as well as the East Coast.
Most infections occur between May and October, when water temperatures are warmer.
How can you get vibrio, aka vibriosis?
Vibriosis occurs when you’re infected with a vibrio bacteria. There are two main routes of vibrio vulnificus infections, says Almagro-Moreno.
The first is through open wounds \u2014 including cuts, scrapes, burns, punctures, surgical incisions and even new tattoos or piercings \u2014 which allow the bacteria to enter the body. This may occur while swimming, wading, fishing or walking on the beach,\u00a0per the CDC.
Vibrio vulnificus may lurk in floodwaters in coastal areas,\u00a0NBC News previously reported. \u201cHurricanes facilitate exposure to the bacteria, because when there\u2019s flooding, the bacterium can enter your home, literally,\u201d says Almagro-Moreno, adding that Florida often sees an uptick in cases after severe hurricanes.
The other route of infection for vibrio vulnificus is through consuming raw or undercooked shellfish, namely oysters, says Almagro-Moreno. Vibrio can also spread if a wound or cut comes into contact with raw or undercooked, contaminated seafood.
Many oysters are harvested from the coastal waters where the bacteria lives,\u00a0per the CDC. Because oysters are filter feeders, they suck up the ocean water along with any vibrio or other germs in it, which then become concentrated in the oyster’s tissues. So, when\u00a0oysters are eaten raw or undercooked, a person can end up ingesting the bacteria along with their meal.
How common are vibrio infections?
Vibriosis (from all species of vibrio) causes an estimated 80,000 illnesses and about 100 deaths in the U.S. every year, according to the CDC. About\u00a052,000\u00a0of these are caused by eating contaminated food, including oysters.
Vibrio parahaemolyticus, which typically causes diarrhea, accounts for the most vibrio infections (about 40%) in the U.S.,\u00a0per the CDC. Infections with vibrio vulnificus are much rarer, with about 150\u2013200 infections reported each year.
Unlike other vibrio species, vibrio vulnificus is primarily transmitted through open wound contact with contaminated water. Only 10% of cases result from eating raw or undercooked shellfish,\u00a0per the CDC.
Anyone can become infected, according to the CDC, but people with compromised immune systems, particularly those with chronic liver disease, are more likely to get vibriosis.
Symptoms of vibrio vulnificus infection
The symptoms of infection with vibrio vulnificus can start within 24 hours of exposure and progress rapidly, says Almagro-Moreno. Most people infected with vibrio have mild symptoms that last no more than three days, per the CDC.
When vibrio vulnificus gets into the bloodstream, it can cause a severe infection with life-threatening complications, says Almagro-Moreno. These include necrotizing fasciitis \u2014 aka flesh-eating disease, where the flesh around an open wound dies \u2014 as well as septic shock and death.
“Many people with this infection require intensive care or tissue removal, and about one in five people with this infection die \u2014 sometimes within a day or two,” a spokesperson for the Enteric Diseases Epidemiology Branch at CDC tells TODAY.com.
A severe infection may require limb amputation or time in the intensive care unit. For mild cases, treatment beyond drinking lots of fluids isn’t usually necessary.
Are vibrio cases and deaths on the rise right now?
It is clear that vibriosis has been increasing in the U.S. in recent decades, according to Almagro-Moreno and recent data.
While the CDC was unable to confirm to TODAY.com whether infections and deaths to due vibrio bacteria rose in 2023, as it’s still waiting for reports from state health departments, CDC surveillance data indicate the incidence of vibriosis increased from 1996 to 2010, according to\u00a0a\u2002study\u2002in the journal Clinical Infectious Diseases.
A 2023\u00a0report from the CDC’s Foodborne Diseases Active Surveillance Network\u00a0found the number of reported vibriosis cases increased in 2022 compared to 2016 to 2018. \u201cMany factors likely contributed, including increases in behaviors like travel and dining out after the peak of the COVID-19 pandemic, and increases in the use of diagnostic tests,\u201d the CDC spokesperson said.
The same report also found that, compared to 2016 to 2018, similar percentages of the vibriosis infections during 2022 resulted in hospitalization and death.
There is also mounting evidence that the geographic range of vibrio vulnificus is expanding.
\u201cI think the trend of cases increasing is mostly associated with the ability of the bacteria to expand geographically,\u201d says Almagro-Moreno. \u201cWe\u2019re getting the bacteria in more places so there\u2019s a higher percentage of the population that can be exposed.”
In addition to hotspots in the Gulf Coast, infections are becoming more common along the Atlantic coastline, the CDC spokesperson said, and vibrio vulnificus infections in the Eastern U.S. alone increased eight-fold from 1988 to 2018.
Water temperature is a clear factor. \u201cIt\u2019s simple: The bacteria cannot live if the water is too cold, so for them to continue expanding up north, the conditions have to be suitable,\u201d says Almagro-Moreno.
He adds that climate change is driving these temperatures up, creating a bigger habitat for the bacteria. The geographic range of vibrio infections has increased north by approximately 48 kilometers per year, per the CDC.
Warmer waters can also cause the bacteria to persist for longer periods of time, the CDC spokesperson said, but more research is needed to understand if rising temperatures will effect the prime season for vibrio, currently May to October.
According to the CDC spokesperson, vibriosis is likely to become more common and emerge in new places in the country. The rise in natural disasters and hurricanes associated with climate change may also increase vibrio exposures, Almagro-Moreno notes.
In its recent advisory, the CDC urged immunocompromised people to exercise caution around coastal water activities and health care professionals to consider vibrio vulnificus as a possible cause of infected wounds that were exposed to coastal waters.
Oysters infected with vibrio do not look, taste or smell any different from other oysters, per the CDC. According to the\u00a0U.S. Food and Drug Administration, eating oysters from \u201cclean waters\u201d or reputable restaurants does not provide protection either.
\u201cThat\u2019s a critical problem that we face \u2026 how to differentiate (oysters) with the pathogenic bacteria beforehand,\u201d says Almagro-Moreno, adding that vibrio surveillance for recreational and food safety purposes is a growing area of research.
In the meantime, people should be informed, not alarmed, Almagro-Moreno says.<\/p>\n\n\n\n