Kiwis have been urged not to consume raw mussels following a spike in Vibrio parahaemolyticus cases - the bacteria that most often causes seafood poisoning.
The Institute of Environmental Science and Research (ESR) has reported 22 cases of Vibrio parahaemolyticus since the start of 2021. That's a notable increase on the 14 cases recorded in the same period last year, and just four the year before that.
Dr Paul Dansted, the director of food regulation at New Zealand Food Safety (NZFS), says an increase in incidence of Vibrio parahaemolyticus is expected in the summer months - but the sharp rise on previous years has prompted the organisation to issue a warning.
He says Kiwis should only eat mussels if they've been cooked thoroughly.
"As undercooked mussels can be a risk factor, it's important to take care with their preparation," Dr Dansted said. "To be safe to eat, thoroughly cook mussels at above 65C for one minute. This will ensure that any Vibrio parahaemolyticus present in the mussels will be destroyed.
"One good way to know when mussels are fully cooked is that their shells pop open when boiled or steamed, and the mussel inside is firm to the touch."
Symptoms of Vibrio parahaemolyticus can be severe, and include bloody or watery diarrhoea, cramps, nausea and vomiting, fever and headaches.
"The consequences can be more serious for people with weakened immunity, the young, the elderly and frail, and pregnant women," Dr Dansted explained.
He says Kiwis should take care when handling, preparing and consuming mussels and follow the Ministry for Primary Industries' three-step protocol for avoiding food poisoning: clean, cook, chill.
NZFS also clarified that the warning against mussel consumption is related just to raw mussels - not the mussels that can be bought in plastic pottles from the supermarket.
"Those mussels are cooked and marinated and are not affected," Dr Dansted said.