It can cause an illness with symptoms including nausea,
stomach cramps, diarrhoea, vomiting, headache, chills and aching muscles.
He would not say where the contaminated oysters had been sold or what
brand they were, saying that was the responsibility of the New Zealand Food
The authority could not be contacted yesterday, but Dr Jarman confirmed the oysters were no longer in shops.
The source of the initial outbreak in Northland could not be determined,
but when further cases were reported in Auckland, a particular brand of oysters
was pinned down as the source of the illness.
The company tested its product and found the oysters came from the batch
which made the Northlanders ill, and pulled them from the market.
Dr Jarman said public health staff were now trying to determine the source of the norovirus.
A health protection team was in Kerikeri on
Friday inspecting septic tanks and looking for contamination. He said it
was not clear whether the oysters were contaminated while still in the
water or during harvesting and processing.
"We look at all the places where contamination may have occurred.
There are a number of possible places from the time when the oysters were
growing in the seawater, during processing, to the
time they were purchased that contamination may have occurred."
Commercial shellfish farming in the inlet has also been halted until the
source of the virus has been found.