Scientific updates related to pathogenic Vibrio spp associated with bivalves and their implications for FAO/WHO risk assessment

FAO and WHO developed risk assessments for Vibrio parahaemolyticus (Vp) and V. vulnificus (Vv) in bivalve mollusks. Subsequently, Codex adopted guidelines endorsing the use of risk tools using local data to inform risk... [ view full abstract ]

FAO and WHO developed risk assessments for Vibrio parahaemolyticus (Vp) and V. vulnificus (Vv) in bivalve mollusks. Subsequently, Codex adopted guidelines endorsing the use of risk tools using local data to inform risk management. The body of knowledge relevant to vibrio risk model assumptions and predictions has expanded greatly. This presentation examines the use of new data to test the skill of existing risk models. Application of vibrio risk assessment models for risk management in bivalve mollusks has been primarily in USA and Canada. Exposure models have demonstrated mixed skill due to high variability Vp and Vv levels in USA oysters. Emerging data indicates that vibrio levels at harvest and post-harvest vibrio growth rates vary between shellfish species. Contrary to existing risk models, total and pathogenic Vp levels are not predictive of risk between different USA regions. However, epidemiological evidence from the USA indicates that models are skilled in relating risk to seasonal levels of total and pathogenic Vp. Additionally, rapid cooling reduces Vp and Vv risk as predicted by vibrio exposure models based on post-harvest growth rates. While the Vp risk assessment was based on sporadic illnesses, occurrence or introduction of “outbreak strains” drive risk. Range expansion of outbreak strains to higher latitudes due to warming waters represents the greatest threat. Emerging pre-harvest mitigations appear to reduce vibrio exposure and risk. Current technology is capable of forecasting vibrio levels and risk on global scale but local data will be key on improving the accuracy of forecasts.