Health experts say eating raw oysters carries a risk of mild food poisoning after 73 people fell ill with norovirus in Auckland.
Auckland Regional Public Health Service medical officer of health Dr Greg Simmons said the victims all ate Pacific oysters from the same company in Clevedon, southeast of Auckland.
The oysters were harvested this month.
The food poisoning was from 14 separate outbreaks where people had eaten the oysters and symptoms included abdominal pains, fever and headache.
Dr Simmons said the disorder was not life-threatening and was like an upset stomach.
He said tests from samples still kept by the company confirmed the virus was in the oysters but the oyster company had done nothing wrong.
Norovirus was carried by humans and oyster beds in Clevedon would have been contaminated, possibly by a sewage discharge from a passing boat.
"The oysters are very efficient at picking up the virus and concentrating it in their gut. Whatever the concentration in the water is, they will concentrate that in several orders of magnitude beyond that." He said eating raw shellfish carried a risk.
"It is a calculated risk but they are a delicacy and New Zealanders are very keen on them," he said.
