Following an evaluation of the risk of contracting a Vibrio infection from consuming seafood in the EU, the European Food Safety Authority (EFSA) warns that resistance to critical antibiotics is increasing in some Vibrio species, and that the prevalence of the pathogen in seafood is expected to increase globally due to climate change.

Alongside the newly released scientific opinion on the matter, EFSA also published a short animated video to explain the relationship between climate change and Vibrio in seafood.

Vibrio are infectious waterborne bacteria that are native to marine coastal areas and brackish waters, and proliferate in temperate to warm waters with moderate salinity. Over the last 20 years, Europe has seen a rise in Vibrio infections thanks to extreme weather events (i.e., heatwaves) and coastal warming, which are increasingly common as an effect of climate change. The Baltic Sea, the North Sea, and the Black Sea are most at risk, as well as coastal areas with large river inflows.

EFSA’s Panel on Biological Hazards (BIOHAZ Panel) reviewed the available scientific data on Vibrio occurrence and concentration in seafood, available analytical methods, pathogenicity to humans and virulence factors, and AMR and persistence mechanisms in different environments. BIOHAZ focused on the species most relevant to seafood: V. parahaemolyticus, V. vulnificus, and non-O1/non-O139 V. cholerae.

Overall, based on a synthesis of the available data, V. parahaemolyticus is present in approximately 20 percent of seafood, with one in five positive samples containing pathogenic strains. Bivalve mollusks and gastropods had the highest number of positive samples (27.8 percent and 28.8 percent, respectively). Pathogenic V. vulnificus was detected in about 6 percent of seafood samples, and was most prevalent in bivalve mollusks (9.9 percent). Non-choleragenic V. cholerae was detected in about 4 percent of the tested seafood samples.

Alarmingly, the BIOHAZ Panel’s assessment found resistance to several antimicrobials, including those of last resort, among Vibrio isolates from seafood/clinical isolates from foodborne infections. The most common resistances were ampicillin (70–100 percent resistance based on seven studies) and streptomycin (30–70 percent, six studies) for V. parahaemolyticus; and colistin (87–100 percent, four studies), ampicillin (4–75 percent, five studies) and streptomycin (11–68 percent, four studies) for non-O1/non-O139 V. cholerae. AMR against medically important antimicrobials (i.e., carbapenems and highly important 3^rd/4^th generation cephalosporins) were increasingly found in the relevant Vibrio species and in imported seafood isolates.

EFSA recommends prioritizing the launch of an EU-wide baseline survey for relevant Vibrio species in pertinent seafood products at primary production and retail to be used as reference to study the effects of climate change on the prevalence of Vibrio in seafood.

In the meantime, to prevent foodborne Vibrio illnesses, EFSA stresses the importance of maintaining cold chain integrity during seafood processing, transportation, and storage. Additionally, to reduce the presence of Vibrio, the agency suggests measures like high-pressure processing (HPP), irradiation, and flash freezing of seafood products, followed by long-term frozen storage. Depuration, which involves placing live mollusks in tanks with clean, circulating seawater to filter out microbes, is also recommended for live oyster consumption.