Latest 'flesh-eating bacteria' outbreaks leave over 100 dead in two years
Hundreds have died in recent outbreaks of the 'flesh-eating' bacteria Vibrio vulnificus and Streptococcus A. By 2026 Vibrio is spreading through the Mediterranean, driven by warming seas, after silently killing for decades.
Calling it "flesh-eating bacteria" is technically inaccurate, but the nickname conveys 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, a progressive destruction of muscle and skin tissue. The two most closely monitored today are Vibrio vulnificus, a marine bacterium, 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 main ways: through an open wound coming into contact with contaminated water, or by eating raw shellfish, especially oysters.
In healthy people, infection usually remains limited to gastrointestinal symptoms. The problem arises in vulnerable groups: patients with liver disease, people with weakened immune systems, diabetes or advanced age. In them, the bacterium can trigger sepsis and tissue necrosis in a matter of hours. According to the US Centers for Disease Control and Prevention (CDC), one in five patients with severe infection dies within a few days.
Streptococcus pyogenes has a very different biology. It is transmitted via respiratory droplets or through skin wounds, not 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 routes of transmission and risk profiles are 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 reported more than 2,600 infections and over 700 deaths linked to this bacterium.
Cases are concentrated along the southern coastline, especially in Florida and Louisiana, where the climate is ideal for it to thrive. In 2024, Hurricane Helene brought coastal flooding in September that drove infections sharply higher: Florida reported 82 cases and 19 deaths, record figures according to state authorities. Total deaths that year linked to Vibrio in Florida 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 total, eight people died from this bacterium in the US in just the first months of that year.
In Asia, the alarm has been raised for a different reason. In Japan, cases of streptococcal toxic shock syndrome caused by Streptococcus pyogenes reached 941 in 2023, a record high at the time. In 2024, that figure was surpassed in barely six months: Japan’s National Institute of Infectious Diseases confirmed 977 infections before the year reached its halfway point, with 77 deaths recorded. The country had registered between 100 and 200 cases of this disease annually since 1992, which makes the recent numbers particularly striking.
Europe, for its part, is facing the problem from the marine side. Between 2014 and 2017, the annual average number of Vibrio infections on the continent was 126. In 2018, an exceptionally hot summer tripled that figure 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 season carried a high level of risk. Spain is not starting from scratch: Galicia has seen three significant outbreaks caused by species of the genus Vibrio over the past two decades – 64 people affected in 1999, 80 in 2004 and almost 100 in 2012 – all linked to consumption of local shellfish.
Heat as an ally: a threat that grows with rising temperatures
The most important question is not just how many have died, but why the numbers keep rising. The answer lies largely in water temperature. Vibrio bacteria 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 warmer the sea surface, the more infections are recorded.
The European Environment Agency estimates that sea surface temperatures in European waters have increased between four and seven times faster than the global ocean average. The Mediterranean, seen by the scientific community as one of the regions most vulnerable to global warming, is especially exposed. And not just because of temperature: as bodies of water shrink in size due to heat, bacteria become more concentrated in what remains, increasing the risk of exposure.
In July 2024, the European Food Safety Authority (EFSA) published an exhaustive assessment of the risks posed by these bacteria, and its message was clear: their prevalence in shellfish is expected to increase, in Europe and worldwide, as a consequence of climate change.
This projection includes a geographical expansion of the bacterium into coastal areas where it is barely detected today. The ECDC, for its part, has developed a surveillance system based on satellite data on sea temperature and salinity, which produces 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, puts it succinctly: "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 peak season means immediate financial 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. Globally, Vibrio infections have increased by more than 84% since the early 2000s, according to consolidated data. If the trend does not change, what is now a sporadic, seasonal risk could become a structural public health problem before 2050.
