The Bay of Plenty shellfish toxin responsible for poisoning 27 people is expected to get much worse.
The number of people who have sought medical help after eating paralytic shellfish collected from the Mount Maunganui and Papamoa coastline since December 12 has risen to 27.
Thirteen people were admitted to Tauranga Hospital after suffering symptoms ranging from tingling around the mouth to difficulty walking.
As of last night, three people remained in hospital.
Bay of Plenty medical officer of health Dr Neil de Wet said algae levels were extremely high in the Bay, so shellfish toxin was expected to get worse.
This underlined the seriousness of the warning that was issued in August, Dr de Wet said.
"Paralytic shellfish poisoning can be a very serious illness, which can even be fatal. People have been really sick after eating shellfish from the Bay of Plenty. Please don't collect or eat shellfish from the affected areas these summer holidays," Dr de Wet said.
Toi Te Ora warned people against the collection of shellfish from Tairua on the Coromandel Peninsula south to Waihi Beach, along the Bay of Plenty coast to Whakatane Heads in the Eastern Bay of Plenty. The warning included Tairua Harbour as well as Tauranga Harbour, Maketu and Waihi estuaries, Matakana and Motiti Islands, and all other islands along this coastline.
The health warning applies to all bivalve shellfish including mussels, pipi, tuatua, cockles, oysters, scallops as well as cat's eyes, snails and kina (sea urchin). Shellfish in the affected area should not be taken or eaten.
Shellfish containing toxic levels of paralytic poison do not look or taste any different to shellfish that are safe to eat. Cooking or freezing them does not remove the toxin. Paua, crayfish and crabs can still be taken but, as always, the gut should be removed before consuming.
"Commercially supplied shellfish are safe to eat, so if you want shellfish on the menu over the holidays visit your supermarket or seafood retailer," Dr de Wet said.
Consumption of shellfish affected by the paralytic shellfish toxin can cause numbness and tingling around the mouth, face, hands and feet, difficulty swallowing or breathing, dizziness and double vision, and in severe cases, paralysis and respiratory failure.
For more information about marine biotoxin alerts visit this website.
For up-to-date information, visit www.ttophs.govt.nz and click on health warnings or call 0800 221 555 and select option 7 to speak to the on-call health protection officer.