New Zealand authorities are considering changing shellfish rules to control Vibrio parahaemolyticus.
The Ministry of Primary Industries (MPI) proposal includes requirements for a Vibrio parahaemolyticus management plan for producers and the supply chain, including triggers where necessary.
The goal of the possible new rules is to minimize the likelihood of Vibrio parahaemolyticus causing disease from commercially harvested bivalve molluscs, including oysters.
Officials said recently they have seen an increase in illnesses due to Vibrio parahaemolyticus associated with the consumption of raw or lightly cooked seafood. Many cases have been traced to recreationally harvested seafood, but some have been linked to commercially farmed shellfish. Cases have been split evenly between the North Island and the South Island with hospitalization rates of up to 40%.
In January this year, 30 cases of illness were reported compared to three in the same month of 2021 and 13 people were hospitalized. The sick people had eaten a variety of raw and cooked seafood, including crayfish, mussels, oysters, cod, snapper and warehou. Several different types of sequences were also identified, which means that there was probably more than one source of contamination.
Potential new requirements
According to the guide, the most important action the industry can take is to minimize the time between harvesting and refrigerating shellfish and to optimize harvesting practices.
Foodborne vibriosis linked to a growing area will trigger a review to assess whether the risk of illness from Vibrio parahaemolyticus in raw shellfish would be considered an annual occurrence. If this condition is met, the cultivation area will have to implement a management plan.
Such a plan should include the growing area and the shellfish species to which it applies; the time or harvest conditions that will cause it to come into operation and cease; and a list of control measures.
The document should be reviewed annually at the same time as the operational control plan and each time the shellfish in the production area are epidemiologically linked to vibriosis infections.
Different regulatory actions will be taken if cases of vibriosis are linked to growing areas. The draft defines the restrictions and criteria for closing and opening commercial cultivation areas, depending on the number of sick people and the duration of the illness.
As Vibrio parahaemolyticus is inactivated by cooking, the requirements will not apply if the molluscs are cooked or treated by another validated process before consumption, or if they are labeled with cooking instructions.
Symptoms of the disease may include watery or bloody diarrhea, abdominal cramps, nausea, vomiting, fever, and headache. They usually occur within 24 hours of consuming a contaminated product and last from one to seven days.
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