Seven people have suffered toxic poisoning after eating shellfish collected from the Bay of Plenty coast.
The case follows last month's warning about the dangers of eating shellfish collected between Mount Maunganui and the Whakatane Heads.
Medical Officer of Health Dr Jim Miller said the seven people affected were the first reported cases of sickness since the Paralytic Shellfish Poisoning (PSP) outbreak in the Bay of Plenty in late 2012.
Dr Miller said five of the people affected had to get hospital treatment.
"This can range from fairly mild symptoms to really quite serious illness," he said.
"Of course, we have no way of knowing exactly how high the levels will be in any particular patch of shellfish along this coastline - so the only safe thing to do is not to eat the shellfish."
Dr Miller said it appeared some people knew about the outbreak but chose to eat the shellfish anyway.
Consumption of shellfish affected by PSP can cause numbness and tingling around the body, difficulty breathing, dizziness and - in severe cases - paralysis and respiratory failure.