Five people have sought hospital treatment after eating contaminated shellfish collected from the Bay of Plenty coastline.
A sixth person also became ill but did not need to go to hospital. The cases occurred over a 24-hour period ending on Monday.
The reports followed Bay public health service Toi Te Ora's November 28 warning against collecting shellfish on the shoreline from Mount Maunganui to Whakatane.
Medical officer of health Jim Miller reiterated that message yesterday.
"It can be quite serious and quite frightening," he said. "The fact that the warning has been out since the November 28, it's quite a concern that people have collected shellfish ... we really want to emphasise how important this is."
Dr Miller said it was the first paralytic shellfish poisoning outbreak since December 2012, in which 29 people were hospitalised.
"Some people ended up quite unwell. At least two people ended up in ICU for a few days. This can be a serious illness and six people [in 24 hours] can be quite a lot".
The six cases involved visitors and local residents who collected shellfish from areas between the Mount and Whakatane. Sunny weekend weather probably resulted in more people visiting beaches, Dr Miller said.
The toxin was a product of algae which tended to grow at this time of year because of the warmer sea and "plenty of nutrition" in the water.
Bay of Plenty Regional Councillor Awanui Black said the ban would impact some families who relied on seafood for Christmas gatherings: "There's a big push around the nation about poverty and these types of food ... (are) free for those who go out and gather it."
Mr Black would like to see a tool created to help people measure the level of toxin while out collecting.
Shellfish with the toxin look and taste the same as those safe to eat. Cooking or freezing does not remove the toxin.
The warning includes all islands and estuaries along the Bay coastline and the health warning applies to all bi-valve shellfish including mussels, pipi, tuatua, cockles, oysters, scallops, cat's eyes, snails and kina (sea urchin).
What to look out for
* Toxin can cause numbness and tingling around the mouth, face, hands and feet; difficulty swallowing or breathing; dizziness; double vision; and in severe cases,
paralysis and respiratory failure.
* Symptoms can start one-two hours after eating toxic shellfish and usually within 12
* Anyone taken ill after eating shellfish should seek urgent medical attention.