Global warming: a flesh-eating bacterium could multiply in our oceans

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On the American coast, swimming can be dangerous. In question, Vibrio vulnificus, a bacterium that causes significant damage to the skin when a wound comes into contact with infected seawater. This flesh-eating bacterium would be particularly sensitive to the warming of the oceans, which would favor its proliferation. This is reported in a study published on March 23 in the journal “ Scientific 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 multiply in the coming years, as the temperature of the oceans increases, particularly on the east coast of the United States where their population could double within twenty years.

A flesh-eating bacterium

Vibrio vulnificus is a marine bacterium of the vibrio family – like cholera. Pathogenic for humans, this bacterium will infect wounds. This is why it is referred to as “flesh-eating bacteria”.

“I don’t really like this image, but it comes down to that,” comments Patrick Monfort, Director of Research at the CNRS. It is really a bacterium whose virulence factors cause serious skin infections”. It all starts with a skin infection, which will necrotize and destroy the flesh. “The wound will become infected. If the infection is not treated, it can end in sepsis. And there, you die,” explains the researcher.

“The risks mainly concern people with specific backgrounds. The number of deaths remains very low”, nuance Patrick Monfort. However, even if the cases remain rare, it is recommended that people with comorbidities take care not to bathe if they have wounds such as cuts or bodily lesions, especially in summer.

One in five cases is fatal

Vibrio vulnificus multiplies when the temperature of the sea water rises on average above 20°C, specifies the National reference center for vibrios and cholera. “There are two factors that favor the presence of this bacterium: the salinity of the water and the temperature”, adds Patrick Monfort, who has been working on Vibrio vulnificus for twenty years. Thus, the higher the temperature of the water, the more the bacteria proliferate. The lower the salinity of the water, the more it multiplies.

“The relationships between the environment and disease agents are complex. It’s important to be aware that the world is changing and how these changes are creating risks to our health,” says Elizabeth Archer, researcher at Britain’s University of East Anglia and lead author of the study.

Ecological changes in the marine environment and global warming provide vibrios with ideal conditions for their proliferation. In the majority of cases, these infections are associated with direct contact with seawater or the consumption of 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 need amputations to avoid blood infection and death.

“This risk exists on the European Atlantic coasts”

“If you have a warming global system, which is expected due to climate change, the temperatures of Atlantic coastal waters rise. At this time, the risk of multiplying the number of vibrios is affirmed. Consequently, the risk of contact with humans increases,” explains Patrick Monfort.

“There are regular cases of infection with Vibrio vulnificus. It’s not just in the United States, it’s also in Europe. This risk also exists on the European Atlantic coasts, and therefore in France”, develops the Research Director. According to him, “the Atlantic is more favorable to Vibrio vulnificus than the Mediterranean, because the Atlantic waters have a lower salinity. And an increase of 1 to 2°C is enough to encourage their multiplication”. In 2000, the National Reference Center already warned, in one of its publications, of the presence of Vibrio vulnificus in French waters.

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