The term "flesh-eating bacteria" is a misnomer, but it captures the terrifying speed with which necrotising fasciitis destroys tissue, sometimes requiring limb amputation within hours. Two bacterial species are primarily responsible: Vibrio vulnificus, a marine organism thriving in warm brackish waters, and group A Streptococcus pyogenes, transmitted between people. While both can cause severe illness, their transmission routes and risk factors differ significantly.
Vibrio vulnificus enters the body through open wounds exposed to contaminated seawater or, more commonly, through consumption of raw shellfish such as oysters and prawns. In healthy individuals, infection often causes only mild gastrointestinal symptoms. However, for those with liver disease, weakened immune systems, diabetes, or the elderly, the bacteria can trigger sepsis and necrosis within hours. According to the US Centers for Disease Control and Prevention, one in five patients with severe infection dies within days.
Group A Streptococcus pyogenes spreads via respiratory droplets or skin wounds, not seawater. Its most dangerous manifestation, streptococcal toxic shock syndrome (STSS), has a mortality rate of around 30%. Although treatable with antibiotics like penicillin, severe cases have risen markedly in recent years.
Global Outbreaks: From Florida to Japan via the Mediterranean
The United States has the best-documented record of Vibrio vulnificus infections, with over 2,600 cases and more than 700 deaths since 1988. Florida and Louisiana, where warm coastal waters provide ideal conditions, are hotspots. In 2024, Hurricane Helene caused coastal flooding that drove infections to record levels: Florida reported 82 cases and 19 deaths, with a total of 89 deaths for the year. By August 2025, Florida had already recorded 13 cases and 4 deaths, while Louisiana saw 17 hospitalised cases and 4 deaths—a 400% increase in fatalities compared to historical averages. The most recent death occurred on 21 July 2025, when a 77-year-old man in Bay St. Louis, Mississippi, died after a scratch on his leg became infected while working with a boat trailer.
In Japan, the focus is on STSS caused by Streptococcus pyogenes. Cases reached 941 in 2023, a record at the time, but were surpassed in just six months of 2024, with 977 infections and 77 deaths. This marks a dramatic increase from the 100–200 annual cases recorded since 1992.
Europe faces the threat primarily from the marine side. Between 2014 and 2017, the continent averaged 126 Vibrio infections annually. The hot summer of 2018 tripled that figure to 445 cases, mainly in Baltic countries: Norway, Sweden, Denmark, Finland, Poland, and Estonia. In June 2026, the European Centre for Disease Prevention and Control (ECDC) warned of a high-risk season ahead. Spain has experienced three significant outbreaks in Galicia over the past two decades: 64 cases in 1999 from oysters, 80 in 2004, and nearly 100 in 2012 from spoiled prawns—all linked to shellfish consumption.
For a deeper look at the European toll, see our report: Flesh-Eating Bacteria Outbreaks Kill Over 100 in Europe in Two Years.
Climate Change as a Driver
The rising number of infections is closely tied to water temperature. Vibrio bacteria thrive between 20°C and 35°C in moderate salinity. These conditions, once limited to tropical and subtropical coasts, now extend each summer to latitudes that were too cold three decades ago. Jan Carlo Semenza, an epidemiologist at Umeå University in Sweden, has documented a direct correlation: higher sea surface temperatures lead to more infections.
The European Environment Agency estimates that sea surface temperatures in Europe have risen four to seven times faster than the global ocean average. The Mediterranean, one of the regions most vulnerable to global warming, is particularly at risk. Shrinking water bodies due to heat concentrate bacterial density, increasing exposure risk. In July 2024, the European Food Safety Authority (EFSA) published a risk assessment concluding that Vibrio prevalence in seafood will increase as a consequence of climate change, both in Europe and worldwide.
The ECDC has developed a surveillance system using satellite data to monitor sea temperatures and predict outbreaks. For more on how warming seas are bringing these bacteria to European beaches, read Warming Seas Bring Flesh-Rotting Bacteria to European Beaches.
As temperatures continue to rise, the threat is expected to expand to coastal areas where it is currently rare. The connection between climate change and public health is becoming impossible to ignore, with Europe at the forefront of this emerging crisis.
