Shellfish poison warning

21:56, Nov 21 2012
POISON WARNING: West coast scallops and all other shellfish are found with high levels of paralytic shellfish poisoning which can be deadly, officials say.

Eating shellfish from the west coast could cause illness and possibly death after the discovery of high poison levels.

Authorities warn against gathering shellfish from Taranaki to Maunganui Bluff, including the Kaipara Harbour entrance, because of high paralytic shellfish poisoning (PSP) levels.

The warning from Auckland and Northland regional public health services covers kina, mussels, pipi, tuatua, toheroa, oysters, cockles, scallops and more. Further information could cause the danger area to be extended.

Shellfish testing shows 1.74 milligrams of toxin per kilogram of shellfish flesh, compared to the safe limit of 0.8mg.

"Anyone eating these toxic shellfish is at risk of illness," Northland medical officer of health Clair Mills says. "Cooking shellfish does not remove the toxin."

PSP symptoms usually develop within 12 hours after eating shellfish containing the toxins and include numbness and tingling around the mouth, face or extremities, difficulty in swallowing or breathing, dizziness and double vision.


Paralysis and respiratory failure may develop in severe cases.

Call 111 for medical help if anybody experiences these symptoms after eating shellfish.

Monitoring will continue and the Northland District Health Board public health unit will advise of any changes.

Toxic algal blooms and shellfish poisoning have been recorded periodically, including a nearly year long episode in 1993.

Those affecting shellfish are relatively common, happening several times a year. Tauranga has been having ongoing problems for most of this year, Northland health board team leader Paul Reid says. But they are uncommon on the west coast with the last big outbreak in 2003.

While there have been no human deaths in New Zealand from marine biotoxins, could occur and care must be taken, Mr Reid says.

● Paralytic shellfish poisoning is caused by a group of chemicals called the saxitoxins and gonyautoxins.

These chemicals all differ in their toxicity to humans and their proportions may vary, depending on the species of shellfish and the species of algae producing the toxin, the Ministry of Primary Industries says. Toxic algae of the species Gymnodinium catenatum, Alexandrium minutum and Alexandrium catenella commonly cause PSP toxicity in shellfish.

Rodney Times