The latest 'flesh-eating bacteria' outbreaks worldwide
In recent years, deaths linked to the 'flesh-eating' bacterium Vibrio vulnificus and group A streptococcus have increased in the United States, Europe and Asia. Warmer seas have allowed Vibrio to spread beyond the Baltic to parts of the North Sea and the Mediterranean.
Calling it 'flesh-eating bacteria' is technically inaccurate, but the nickname does capture what it does: destroying tissue so fast that limbs have to be amputated within hours.
The popular label in fact covers several bacterial species capable of causing necrotising fasciitis, the progressive destruction of muscle and skin tissue. The two most closely monitored today are Vibrio vulnificus, which lives in the sea, and group A Streptococcus pyogenes, which spreads from person to person.
Vibrio lives in warm, brackish waters, where rivers flow into the sea, and reaches humans in two ways: when an open wound comes into contact with contaminated water, or through eating raw seafood, especially oysters.
In healthy people, infection usually causes no more than gastrointestinal symptoms. The real danger is for vulnerable groups: people with liver disease, weakened immune systems, diabetes or advanced age. In them, the bacterium can trigger sepsis and tissue necrosis within hours. According to the United States Centers for Disease Control and Prevention (CDC), one in five patients with a severe infection dies within a few days.
Streptococcus pyogenes behaves very differently. It spreads via respiratory droplets or through breaks in the skin, not through seawater. In its most dangerous form it causes streptococcal toxic shock syndrome (STSS), with a mortality rate of around 30%.
Although it has been known for decades and responds well to antibiotics such as penicillin or amoxicillin, the number of severe cases has risen strikingly in recent years. The two bacteria share the same nickname, but their transmission routes and risk profiles are very different.
The latest outbreaks: from Florida to Japan via the Mediterranean
The recent record of Vibrio vulnificus in the United States is the best documented in the world. Since 1988 the country has recorded more than 2,600 infections and over 700 deaths linked to this bacterium.
Cases are concentrated along the southern coast, especially in Florida and Louisiana, where the climate is ideal for it to flourish. In 2024, Hurricane Helene brought coastal flooding in September that sent infections soaring: Florida reported 82 cases and 19 deaths, record figures according to state authorities. Total deaths in Florida that year associated with Vibrio reached 89, according to the state Department of Health.
The year 2025 was no better. By August, Florida had recorded 13 cases and 4 deaths, while Louisiana – where the historical average rarely exceeded one death a year – reported 17 hospitalised cases and another 4 deaths, a 400% increase in fatalities compared with previous years.
The most recent case occurred on 21 July 2025, when a 77-year-old man died in Bay St. Louis, Mississippi, after becoming infected through a scratch on his leg while working with a boat trailer. In all, eight people died from this bacterium in the US in just the first few months of that year.
In Asia, the alarm has centred on something different. In Japan, cases of streptococcal toxic shock syndrome caused by Streptococcus pyogenes reached 941 in 2023, the highest figure on record to date. In 2024, that number was surpassed in barely six months: Japan’s National Institute of Infectious Diseases confirmed 977 infections before the year’s halfway point, with 77 deaths recorded. The country had registered between 100 and 200 cases of this disease a year since 1992, which makes the recent figures particularly striking.
Europe, meanwhile, is facing the problem from the marine side. Between 2014 and 2017, the continent recorded an average of 126 Vibrio infections a year. In 2018, an exceptionally hot summer tripled that number to 445 cases, mainly in Baltic countries: Norway, Sweden, Denmark, Finland, Poland and Estonia.
In June 2026, as summer began, the European Centre for Disease Prevention and Control (ECDC) was already warning that the coming season would carry a high level of risk. Spain does not start from zero: Galicia has seen three significant outbreaks caused by species of the Vibrio genus in the past two decades: 64 people affected in 1999, 80 in 2004 and almost 100 in 2012, all linked to the consumption of contaminated local shellfish. None of those cases resulted in death.
Heat as an ally: a threat that rises with the thermometer
The key question is not just how many people have died, but why the numbers keep rising. Much of the answer lies in water temperature. Bacteria of the Vibrio genus thrive at between 20°C and 35°C in waters with moderate salinity.
Those conditions, previously confined to tropical and subtropical coasts, now extend every summer to latitudes that thirty years ago were too cold for this microorganism. Jan Carlo Semenza, an epidemiologist at Umeå University in Sweden, has documented this direct correlation: the higher the sea surface temperature, the more infections are recorded.
The European Environment Agency estimates that sea surface temperatures in European waters have risen between four and seven times faster than the global ocean average. The Mediterranean, regarded by the scientific community as one of the regions most vulnerable to global warming, is especially exposed. And not only because of temperature: as bodies of water shrink in size under the effect of heat, bacteria become more concentrated in what remains, increasing the risk of exposure.
In July 2024, the European Food Safety Authority (EFSA) published a comprehensive assessment of the risks posed by these bacteria and was unequivocal: their prevalence in seafood is expected to increase, in Europe and globally alike, as a consequence of climate change.
This projection includes a geographical spread of the bacteria to coastal areas where they are barely detected today. The ECDC, for its part, has developed a surveillance system based on satellite data on sea temperature and salinity, generating real-time risk maps to guide national alerts.
The impact is not only on health. Hatim Aznague, Climate Action and Energy Resilience analyst at the Union for the Mediterranean, sums it up neatly: 'The bacteria are not the story; they are the messengers. The story is a sea thrown out of balance by heat and pollution.' A beach closed in high season means immediate losses for hotels, restaurants and tour operators.
The Mediterranean is the most visited holiday region in the world, which amplifies the impact of any health alert. Globally, Vibrio infections have risen by more than 84% since the early 2000s, according to consolidated data. If the trend continues, what is now a sporadic, seasonal risk could turn into a long-term structural public health problem.
