Seven Australian states have recorded more than 100 Vibrio illnesses linked to raw oysters from South Australia.

There are 56 people sick in South Australia since September and three have been hospitalized. Western Australia has 17 cases since late September, Victoria reported 31 illnesses since the first week of October and 15 infections have been recorded in New South Wales. Further illnesses have also been reported in Queensland and the Northern Territory.

Two cases of Vibrio parahaemolyticus were identified in the Australian Capital Territory in people who had recently consumed oysters. Investigations are ongoing to find out wher they were sourced from.

Oyster recall
Raw Pacific oysters produced in Coffin Bay, South Australia, including fresh and frozen products, have been recalled. All production dates from Sept. 4, to Nov. 16, 2021, are affected.

The recalled oysters

They were sold direct from farms, seafood outlets, grocery stores and supermarkets in South Australia (SA), New South Wales (NSW), the Australian Capital Territory, Queensland, Victoria, the Northern Territory and Western Australia.

The Department of Primary Industries and Regions SA (PIRSA) has closed oyster production areas in Coffin Bay as a precaution as part of the investigation. Traceback work has identified production areas in Coffin Bay as the source of the oysters consumed by some sick people, but the specific cause of contamination is still unknown.

PIRSA, SA Health and the state’s oyster industry are investigating the outbreak and implementing risk management measures. Vibrio parahaemolyticus has been confirmed in oysters from Coffin Bay.

Nathan Rhodes, PIRSA executive director of biosecurity, said the formal closure means no oysters can leave the area.

“This precautionary closure has been put in place to provide us with the opportunity to traceback recent cases and enable further investigations,” he said.

“PIRSA has consulted with industry, who have supported the closure, and has been working with SA Health on the public health impacts of the outbreak. Many growers had already voluntarily closed their harvesting operations.”

PIRSA is also ensuring best practice quality controls are in place for the rest of the South Australian oyster sector to ensure safe supply to the market.

Consumer advice
Chris Lease, SA Health’s deputy chief public health officer, encouraged people to either throw away any Coffin Bay oysters or return them to their place of purchase.

“This recall is an additional safety measure on top of the precautionary closure of the Coffin Bay growing area recently imposed by the Department of Primary Industries and Regions,” he said.

Keira Glasgow, acting director of NSW Health’s enteric investigation branch, urged people across the state to stop consuming oysters from the Coffin Bay region until the source was identified and controlled.

“NSW Health is aware of at least 15 people who have been diagnosed with Vibrio parahaemolyticus infection this month. Those who have been interviewed have reported recently eating raw Pacific oysters, which have been traced back to the Coffin Bay region of South Australia. Preliminary laboratory investigation suggests a link to cases identified in other states and territories,” she said.

Improper handling or consumption of raw or inadequately cooked oysters from Coffin Bay at this time puts anyone at risk of infection.

Implicated oysters were also exported to Hong Kong and Singapore. The Centre for Food Safety (CFS) instructed firms to suspend import and sale of the oysters while the Singapore Food Agency told three importers to recall the product.

Symptoms of Vibrio infections include watery diarrhea, nausea, vomiting, fever, abdominal pain, headache and muscle aches, and usually occur within 24 hours of eating contaminated products. Most people recover with rest and fluids and symptoms are usually mild to moderate lasting about three days but can be more severe in the elderly and people who are immunosuppressed.