Wairarapa’s coasts are a hotspot for fishing and diving, but New Zealand Food Safety [NZFS] is warning of an increase in cases of gastroenteritis from eating shellfish harbouring pathogenic bacteria.
NZFS is warning people to make sure they thoroughly cook the shellfish they collect this summer after cases of gastroenteritis caused by vibrio parahaemolyticus have spiked in recent months.
It said vibrios were a type of bacteria naturally living in the sea, but some strains could make people sick with gastroenteritis [gastro] when consumed in raw or undercooked shellfish.
“Our message to those who want to eat raw or lightly cooked shellfish – like mussels, kina, and pipi – is to be aware there are increased risks of illness and the simple precautions you can take to protect yourselves and your families,” NZFS deputy director-general Vincent Arbuckle said.
He said there had been an increase in cases of the illness, but the cause was hard to identify.
In 2015, Wairarapa Hospital locked down a ward after an outbreak of gastroenteritis.
The outbreak was not reported to be linked to shellfish consumption.
Arbuckle said there was a possibility of rising sea temperatures were making it easier for bacteria to spread.
“As we gear up for summer, and enjoy time with family and friends over the holidays, we need to make sure to take extra care when collecting and preparing shellfish.”
Arbuckle said there were 60 reported cases of vibrio parahaemolyticus, between November 2021 and May 2022 across the nation.
He said there had been a high hospitalisation rate of almost 42 per cent.
Ministry of Primary Industries said in a 2018 risk profile of the bacteria that the risk to New Zealanders of vibrio parahaemolyticus infection from commercially harvested shellfish was low considering the small number of cases being reported until 2018.
“However, the risk may rise as coastal water temperatures increase as a result of climate change.” It said the concentration of the bacteria in the ocean was highly correlated with water temperature, especially during summer months. However, the correlation reduced for pathogenic strains of vibrio parahaemolyticus.
Arbuckle said 24 cases were recorded before November 2021, 16 cases in 2020 and 23 cases in 2019.
“The reason for the increase is unclear at this stage – it could be caused by environmental change, increased testing and reporting, or a combination of these and other factors – but it is clear, that cooking your shellfish kills the bacteria that makes you sick.”
He said the bacteria could cause illnesses such as gastroenteritis – with symptoms including diarrhoea, abdominal cramps, nausea, vomiting and fever – blood poisoning, and wound infections.
“It’s especially important for those with underlying health conditions, pregnant and older people, and younger children to avoid eating raw shellfish.”
Arbuckle said NZFS wanted people to know there were easy, tasty ways to make the kai moana [seafood] safe for eating, so it released a series of simple recipes, created by a community chef.
He said the recipes were available on the NZFS website.
“On our own, we can’t control the changing environmental factors, but we can all help look after our whanau and reduce the risk of them falling sick from Vibrio by taking some simple precautions – and by spreading the word on safe ways to cook shellfish.”
Arbuckle said people should avoid eating raw shellfish, cook shellfish at at least 65 degrees Celsius for one minute, and avoid gathering shellfish after heavy rainfall.
“Keep shellfish alive and cool.”
He said shellfish should be refrigerated as soon as possible and, ideally, eaten on the day of collection or within two days.
