Dar seafood ppp standard

4.4.4.1 Oysters and other bivalve molluscs

Oysters and other bivalve molluscs (except when the consumed product is only the adductor muscle, e.g. roe-off scallops) harvested from growing environments vulnerable to faecal contamination and/or not under a shellfish safety management scheme present a relatively high risk to public health, mainly due to the likelihood of illness caused by contamination with hepatitis A virus and algal biotoxins (particularly Neurotoxic Shellfish Poisoning [NSP]; and Amnesic Shellfish Poisoning [ASP]). These hazards are introduced in the pre-harvest phase of bivalve production.

This relatively high risk ranking is consistent with other studies based on recent epidemiological data that reflected a situation where inconsistent risk management systems were in place across Australia.
Food-borne illness due to oysters and other bivalve molluscs in Australia have resulted in a number of small outbreaks and sporadic cases due to Vibrio species and a few large outbreaks due to enteric viruses in oysters harvested from polluted and inadequately controlled waters.
While adoption of risk management strategies has improved the safety of bivalve shellfish in recent times, some risk remains. While monitoring of harvest waters for indicators of sewage pollution (e.g. faecal or total coliforms) helps to manage the risks due to enteric pathogens, bacterial and viral, it cannot predict levels of Vibrio species and enteric viruses in oysters. Oysters harvested from waters without a risk management system in place have a higher risk of contamination by algal toxins. Therefore, where oysters and bivalves are harvested from waters managed under a comprehensive shellfish safety scheme, such as the Australian Shellfish Quality Assurance Program (ASQAP), the risk is significantly reduced, notably, the likelihood of a food-borne illness is very low.
The risk rankings for oysters and other bivalves were the same regardless of whether they were to be cooked or eaten raw, as the hazards leading to the risk rankings are not greatly affected by the light cooking normally applied to these products.