The European Food Safety Authority (EFSA) has tasked the Biological Hazards Panel (BIOHAZ) with developing a scientific opinion on public health aspects related to Vibrio species in seafood consumption within the European Union.
According to EFSA’s latest assessment, the prevalence of Vibrio in seafood is expected to increase both globally and in Europe due to climate change, particularly in brackish or low-salinity waters. Additionally, some Vibrio species are increasingly resistant to last-resort antibiotics.
The analysis focuses on three relevant Vibrio species: Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae non-O1/non-O139, although other species are considered when relevant.
Vibrio: The Silent Killer Hidden in Seafood
Vibrio bacteria are a group of microorganisms that inhabit aquatic environments, especially coastal waters. While many species are harmless, some pose a serious public health risk. Among these, Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae non-O1/non-O139 are the main concerns in the European Union due to their close association with seafood consumption.
Presence and Concentration of Vibrio spp.
EFSA reviewed existing information on the presence and concentration of Vibrio spp. in seafood. The combined prevalence of V. parahaemolyticus in various seafood categories was 19.6%, with the highest estimates in bivalve mollusks (27.8%) and gastropods (28.8%). Additionally, approximately 18.4% of positive samples contained pathogenic strains. For V. vulnificus, the combined prevalence was 6.1%, highest in bivalve mollusks at 9.9%. The combined prevalence of V. cholerae non-O1/non-O139 was 4.1%.
Detection and Characterization Methods
Standardized microbiological methods exist for detecting relevant Vibrio species in seafood, including molecular tests for species identification and pathogenicity gene detection. Alternative approaches like LAMP-PCR and MALDI-TOF MS are also used. For characterization, sequencing technologies such as MLST and WGS are increasingly applied for the comprehensive characterization of clinical Vibrio isolates and outbreak investigations.
Virulence Factors and Antimicrobial Resistance
Pathogenic Vibrio species possess various virulence factors that enable them to colonize and spread in hosts. The virulence of V. parahaemolyticus is significantly associated with TDH and TRH hemolysins. V. vulnificus primarily affects individuals with underlying health conditions, while V. cholerae non-O1/non-O139 generally causes self-limiting gastroenteritis or mild symptoms.
Regarding antimicrobial resistance, a wide range of resistances has been reported in Vibrio isolates, with the most common being resistance to ampicillin and streptomycin for V. parahaemolyticus, and to colistin and ampicillin for V. cholerae non-O1/non-O139. Resistance to important antimicrobials like carbapenems and third- and fourth-generation cephalosporins has also been detected.
Factors Influencing Vibrio spp. Occurrence and Growth
EFSA identified several factors in aquatic environments and food that influence Vibrio spp. occurrence and growth. Temperature is the most relevant factor, followed by water salinity. Other factors include solar and UV radiation, pH, water activity in food, and nutrient content. Additionally, the transmission of virulence or resistance determinants can be affected by the presence of chitin and phages.
Impact of Climate Change
Climate change induces more suitable conditions for the growth and persistence of Vibrio spp. in aquatic environments. It affects the geographic distribution of coastal areas suitable for Vibrio, the temporal distribution of these conditions, and the frequency and intensity of extreme weather events. The occurrence and levels of Vibrio spp. in seafood are anticipated to increase in response to coastal warming and extreme weather events.
Prevention and Control Measures
EFSA reviewed prevention and control measures along the food chain for Vibrio spp. Maintaining the cold chain is crucial to prevent Vibrio growth in seafood. Mild heat treatments, freezing, high-pressure processing, and irradiation are effective in reducing Vibrio presence. Depuration under controlled conditions is also an option for the live oyster market.
Risk Assessment Models and Future Research Areas
EFSA identified risk assessment modeling options for Vibrio spp. in seafood and the knowledge gaps needed to conduct an EU-level risk assessment. It is recommended to develop an EU-level baseline survey for Vibrio spp. in relevant seafood products, improve analytical methods, and characterize virulence factors and antimicrobial resistance.
Conclusions
EFSA highlights the need to systematically monitor the occurrence of Vibrio spp. in seafood, characterize clinical and food isolates using WGS, and develop Vibrio suitability maps in the EU. These measures are essential to address public health challenges related to Vibrio spp. in the context of ongoing climate change.
Based on the study, the following recommendations are proposed:
- Systematic Monitoring: Implement systematic monitoring of Vibrio spp. in seafood and aquatic environments.
- Isolate Characterization: Use sequencing technologies for the comprehensive characterization of Vibrio isolates.
- Risk Assessment Models: Develop and validate EU-specific risk assessment models.
- Control Measures: Maintain and enhance control measures along the food chain, including the cold chain and post-harvest treatments.
This article underscores the importance of continuous surveillance and robust preventive measures to ensure the safety of seafood in the EU and protect public health against Vibrio spp. infections.
Contact
EFSA Panel on Biological Hazards (BIOHAZ)
Email: biohaz@efsa.europa.eu
Reference (open access)
Koutsoumanis, K., Allende, A., Alvarez-Ordóñez, A., Bolton, D., Bover-Cid, S., Chemaly, M., Cesare, A. D., Herman, L., Hilbert, F., Lindqvist, R., Nauta, M., Nonno, R., Peixe, L., Ru, G., Simmons, M., Skandamis, P., Baker-Austin, C., Hervio-Heath, D., Martinez-Urtaza, J., . . . Suffredini, E. (2024). Public health aspects of Vibrio spp. Related to the consumption of seafood in the EU. EFSA Journal, 22(7), e8896. https://doi.org/10.2903/j.efsa.2024.8896
