Global warming: Carnivorous bacteria could breed in our oceans

Swimming on the American coast can be dangerous. This is Vibrio vulnificus, a bacterium that causes significant damage to the skin when a wound comes into contact with contaminated seawater. This carnivorous bacterium will be especially sensitive to warming oceans, which will encourage it to multiply. This is reported in a study published March 23 in the journal Science Reports. Particularly active in the United States, the bacterium thrives in warm coastal waters and can cause deadly infections.

According to scientists, vibrio vulnificus is likely to proliferate in the coming years as ocean temperatures rise, especially on the East Coast of the United States, where their population could double within twenty years.

Carnivorous bacterium

Vibrio vulnificus is a marine bacterium of the vibrio family, similar to cholera. Human pathogenic bacteria infect wounds. That’s why it’s called “flesh-eating bacteria.”

“I don’t really like this image, but it all boils down to this,” comments Patrick Monfort, director of research at CNRS. It is indeed a bacterium whose virulence factors strongly attack the skin infection.” It all starts with a skin infection that necrotizes and destroys the flesh. “The wound will get infected. If the infection is not treated, it can end in sepsis. And there you will die,” explains the researcher.

“Risks mostly concern people with a certain background. The number of deaths remains very low,” notes Patrick Monfort. However, even if cases remain rare, it is recommended that people with comorbidities not take a bath if they have wounds such as cuts or bodily injuries, especially in summer.

Every fifth case is fatal

Vibrio vulnificus multiplies when sea water temperature rises above 20°C on average, indicates National Reference Center for Vibrios and Cholera. “There are two factors that contribute to the presence of this bacterium: water salinity and temperature,” adds Patrick Monfort, who has been working on Vibrio vulnificus for twenty years. Thus, the higher the water temperature, the more bacteria multiply. The lower the salinity of the water, the more it breeds.

“The relationship between the environment and pathogens is complex. It is important to be aware that the world is changing and how these changes pose risks to our health,” says Elizabeth Archer, a researcher at the British University of East Anglia and lead author of the study.

Environmental changes in the marine environment and global warming create ideal conditions for the reproduction of vibrios. In most cases, these infections are associated with direct contact with sea water or eating seafood and occur during the hottest months of the year. According to the US Centers for Disease Control and Prevention (CDC), one in five cases is fatal, and many people require amputation to avoid blood poisoning and death.

“This risk exists on the European Atlantic coast”

“If you have global warming, which is expected due to climate change, the temperature of the coastal waters of the Atlantic rises. At this time, the risk of a multiple increase in the number of vibrios is confirmed. Consequently, the risk of contact with people increases,” explains Patrick Monfort.

“There are regular cases of infection with Vibrio vulnificus. This is not only in the US, but also in Europe. This risk also exists on the European Atlantic coast and therefore in France,” the research director develops. According to him, “The Atlantic is more favorable for Vibrio vulnificus than the Mediterranean Sea, because the Atlantic waters have less salinity. And an increase of 1-2°C is enough to stimulate their reproduction. In 2000, the National Reference Center already warned in one of its publications about the presence of Vibrio vulnificus in French waters.