New Zealand Food Safety is urging people to ensure they cook raw mussels thoroughly after an increase in cases of food poisoning associated with commercially grown New Zealand mussels.

Image by RitaE from Pixabay

Over the past 6 weeks, there has been an increase in cases of people with food poisoning caused by Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a marine microorganism that occurs naturally throughout the world.  Not all Vibrio parahaemolyticus strains cause illness in humans and surveys to date of New Zealand shellfish have found very low levels and incidence of disease-causing strains.

However, some strains do cause illness in humans.  Symptoms are predominantly stomach cramps and watery diarrhoea and sometimes nausea, vomiting and fever.  Generally people who are sick recover without hospital treatment, however, in severe cases hospitalization is required.

New Zealand Food Safety’s director of food regulation Paul Dansted says the majority of people who have become sick have bought commercially-grown New Zealand mussels harvested from a single growing area in the Coromandel and were eaten raw or partially cooked. This growing area has been closed by New Zealand Food Safety while further investigations continue.

“Additional testing is being done to confirm the type of Vibrio parahaemolyticus that has caused this illness.  It is possible that the strain of Vibrio parahaemolyticus is unusually aggressive which may mean that even low numbers could cause illness.

“Additional testing of mussels and the waters that they are being grown in is also underway to help us understand why this has happened.

“The mussels at the centre of the outbreak were all bought in their raw state, in the shell. They are not the mussels that can be bought in plastic pottles. Those mussels are cooked and marinated and are not affected.

“Until we have more information, New Zealand Food Safety is reminding people to take care when handling, preparing, and consuming mussels.”

Cooking temperatures for mussels should be above 65°C. This will ensure that any Vibrio parahaemolyticus that is present in mussels will be destroyed.

  • Don’t eat raw or undercooked mussels or other shellfish. Cook them before eating.
  • Always wash your hands with soap and water after handing raw shellfish.
  • Avoid contaminating cooked shellfish with raw shellfish and its juices.

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