Recent 'flesh-eating bacteria' outbreaks worldwide
In recent years, deaths linked to the “flesh‑eating bacterium” Vibrio vulnificus and group A streptococcus have risen in the US, Europe and Asia, as warmer seas let Vibrio spread from the Baltic to parts of the North Sea and the Mediterranean.
Calling it a "flesh-eating bacterium" is technically inaccurate, but the nickname does help convey what it does: it destroys tissue so fast that limbs have to be amputated within hours.
The popular term actually covers several bacterial species capable of causing necrotising fasciitis, the progressive death of muscle and skin tissue. The two most closely watched today are Vibrio vulnificus, which is marine in origin, and group A Streptococcus pyogenes, which spreads from person to person.
Vibrio thrives 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 the consumption of raw shellfish, especially oysters.
In healthy people, the infection is usually confined to gastrointestinal symptoms. The problem arises in vulnerable groups: people with liver disease, weakened immune systems, diabetes or advanced age. In them, the bacterium can trigger sepsis and 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 differently. It is transmitted via the respiratory route or through skin wounds, 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 a nickname, but their transmission routes and risk profiles are different.
The latest outbreaks: from Florida to Japan via the Mediterranean
The recent history 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, with 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 proliferate. In 2024, Hurricane Helene’s landfall in September caused coastal flooding that sent infections soaring: Florida reported 82 cases and 19 deaths, record figures according to state authorities. The total number of deaths that year linked to Vibrio in Florida reached 89, according to the state’s 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 a further 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 focus of concern has been different. In Japan, cases of streptococcal toxic shock syndrome caused by Streptococcus pyogenes reached 941 in 2023, the highest figure on record. In 2024, that number was surpassed in barely six months: Japan’s National Institute of Infectious Diseases confirmed 977 infections before the halfway point of the year, with 77 deaths recorded. The country had been registering between 100 and 200 cases of this disease a year since 1992, which makes the recent figures particularly striking.
Europe, for its part, is facing the problem from the marine front. Between 2014 and 2017, the average annual number of Vibrio infections on the continent stood at 126. In 2018, an especially hot summer tripled that to 445 cases, mainly in Baltic countries: Norway, Sweden, Denmark, Finland, Poland and Estonia.
In June 2026, as summer began, so did a season that the European Centre for Disease Prevention and Control (ECDC) was already classifying as high risk.
Spain is not starting from scratch: Galicia has recorded three significant outbreaks caused by Vibrio species over the past two decades: 64 people were affected in 1999 after eating oysters, 80 in 2004 and nearly 100 in 2012 after eating spoiled prawns. In Spain’s case, the outbreaks were linked to shellfish consumption.
Heat as an ally: a threat that grows as temperatures rise
The key question is not just how many people have died, but why the numbers keep going up. The answer lies largely in water temperature. Bacteria of the Vibrio genus thrive between 20°C and 35°C in waters with moderate salinity.
Those conditions, once confined to the tropics 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.
The European Environment Agency estimates that sea surface temperatures in Europe have risen between four and seven times faster than the global ocean average. The Mediterranean, viewed by the scientific community as one of the regions most vulnerable to global warming, is particularly exposed. And not only because of temperature: as bodies of water shrink under the effect of heat, bacterial density increases in what remains, raising the risk of exposure.
In July 2024, the European Food Safety Authority (EFSA) published a comprehensive risk assessment of these bacteria, with a clear conclusion: their prevalence in seafood is expected to increase, both in Europe and worldwide, as a consequence of climate change.
This projection includes the geographical spread of the bacterium to coastal areas where it is currently barely detected. The ECDC, for its part, has developed a monitoring system based on satellite data (source in Spanish) on sea temperature and salinity, which generates real-time risk maps to guide national alerts. The main hotspots currently forecast are the Black Sea, the North Sea and the Baltic.
The impact is not only on health. Hatim Aznague, a 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 off balance by heat and pollution." A beach closed in high season means immediate losses for hotels, restaurants and tour operators.
The Mediterranean is the world’s most visited holiday region, which magnifies the impact of any health alert. Vibrio infections have risen by more than 84% globally since the early 2000s, according to consolidated data. If the trend continues, what is now a seasonal, localised risk could turn into a structural public health problem in the medium term.
