EUROPE – As global temperatures continue to rise, scientists are increasingly concerned about the growing prevalence of Vibrio bacteria in seafood.
An assessment by the European Food Safety Authority (EFSA) has projected that the occurrence and levels of Vibrio will escalate due to coastal warming and extreme weather events, such as heatwaves. This trend poses potential health risks to consumers and challenges to food safety authorities.
Vibrios are waterborne bacteria primarily found in marine coastal waters and brackish areas where rivers meet the sea. They thrive in warm waters with moderate salinity, conditions that are becoming more common due to climate change.
Among the various species, Vibrio parahaemolyticus, Vibrio vulnificus, and non-O1/non-O139 Vibrio cholerae are of the highest relevance for public health in the European Union (EU) through seafood consumption. The scientific assessment did not consider infections arising from environmental, recreational, or occupational exposure.
Increasing trends and implications
EFSA’s evaluation included a review of 46 studies conducted in 16 countries between 2000 and 2022. Vibrio parahaemolyticus was found in 20 percent of over 10,600 seafood samples, with one in five positive samples containing pathogenic strains.
Vibrio vulnificus was detected in approximately 6 percent of nearly 3,000 samples, while the prevalence of non-chlorogenic Vibrio cholerae was estimated at 4 percent.
The EU has reported 32 outbreaks attributed to Vibrio in seafood from 2010 to 2021, resulting in 221 cases, with 57 hospitalizations. Additionally, the Rapid Alert System for Food and Feed (RASFF) issued 75 notifications concerning Vibrio in seafood from 2010 to January 2023, though only four were linked to food originating within the EU.
A major outbreak in Australia in 2021 involved Vibrio parahaemolyticus in raw oysters, affecting over 250 people. This event led to Food Standards Australia New Zealand (FSANZ) seeking data from several countries, including EU members, on Vibrio prevalence in seafood in 2022.
In 2022, the German Federal Institute for Risk Assessment (BfR) published a health risk assessment highlighting the importance of cooking seafood properly to prevent Vibrio infections. The report emphasized that the consumption of raw or insufficiently cooked seafood is a critical factor in the transmission of Vibrio.
Climate change and the viability of Vibrios
The rising ocean temperatures are facilitating the spread and growth of Vibrio bacteria, leading to increased contamination risks in seafood.
Changes in environmental factors such as temperature, salinity, pH, oxygen concentration, and nutrient availability can induce Vibrios into a viable but non-culturable state. This ability to adapt and form biofilms complicates the detection and elimination of these bacteria in seafood.
High-pressure processing, irradiation, and depuration are methods that can reduce Vibrio levels in seafood, but maintaining a strict cold chain from catch to consumer is crucial to prevent bacterial growth. EFSA’s assessment highlights the need for more robust food safety practices to address these emerging risks.
Antimicrobial Resistance: A growing concern
Recent studies on Vibrio isolates from seafood and foodborne infections in Europe have identified resistance to multiple antimicrobials, including those considered as last-resort treatments. This development adds another layer of complexity to managing Vibrio-related food safety issues, as antibiotic-resistant strains pose significant challenges to public health systems.
The scientific community has emphasized the importance of monitoring antimicrobial resistance in Vibrio species and developing strategies to mitigate its impact. The interplay between climate change, bacterial prevalence, and resistance patterns demands coordinated efforts to protect public health.
Calls for enhanced surveillance and reporting
In light of these findings, scientists and food safety experts have called for comprehensive measures to address the growing Vibrio threat. Establishing an EU-wide baseline survey for Vibrio in seafood products, covering primary production and retail stages, is seen as a priority for future research.
Additionally, developing a standardized case definition for human vibriosis at the EU level and considering the inclusion of vibriosis in compulsory reporting systems have been recommended.
Increased surveillance and reporting will enable authorities to better understand the epidemiology of Vibrio infections and implement targeted interventions to safeguard consumers. The need for improved data collection and analysis is particularly pressing as climate change continues to alter environmental conditions, potentially exacerbating the prevalence of Vibrio in seafood.
In the U.S., the Centers for Disease Control and Prevention (CDC) has also reported increasing cases of Vibrio infections, particularly in regions experiencing warmer coastal temperatures. This underscores the need for a coordinated global response to address the challenges posed by climate change and its impact on seafood safety.
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