Levels and presence of pathogenic Vibrio spp. associated with oysters do not correlate with the presence of faecal indicator organisms currently used to monitor presence of enteric viruses and bacteria. Consequently, marine vibrios represent a risk to public health that has not been rigorously assessed and is currently not monitored.
Presence of marine vibrios may affect foreign market access. Japan and Denmark specify levels of V. parahaemolyticus in oysters of <100 organisms/gram. In some European countries, raw seafood is rejected if Vibrio spp. are detected. California has banned raw oysters from the Gulf of Mexico as part of a strategy to minimise V. vulnificus related illness (Food Safety Network 6/1/05 see archives.foodsafetynetwork.ca/fsnet/2005/1-2005/fsnet_jan_6.htm#story). Currently, the SA industry has little systematic data to satisfy foreign inspection requirements, despite the fact that a recent small-scale survey of SA oysters indicated levels of pathogenic vibrios exceeded 100 per gram (see Lewis etal, 2002. FRDC project 2002/409 report). Whether these levels persist to retail under current industry cool-chain practices is not known.
Analysis of numbers of marine vibrios and their potential to cause disease will allow:
1. Evaluation of risk and development of an appropriate monitoring systems (i.e. frequency, intensity of sampling, temporal variation etc.).
2. Minimisation of risk through development of recommendations for harvest and post-harvest handling processes.
3. Provision of defensible data for foreign food inspection agencies.
4. Support of programs that aim to improve consumer confidence.
Government and industry development priorities addressed include:
1. SA Fisheries and Aquaculture R&D Strategy (2002-2007). The SA Food Act (2001) will leverage the seafood industry towards higher quality control and food safety procedures. Through an enhanced capability to satisfy local and overseas market demands, a premium product may attract a higher commodity prices.
2. Food safety issues identified by this project also fall well within the current and future SAORC and the FRDC strategic and R&D plans. Specifically, SAORC has identified the need to determine optimum storage temperature regimes for post harvest oyster product that enhance food safety. Understanding the impact of storage on numbers and viability of marine vibrios associated with oysters is one aspect of this overall aim.
3. The SA Seafood Industry Development Board aims to maximize industry growth by encouraging whole-of-chain management practices to ensure ultimate market access and success.
