A fifth case of hepatitis A is likely to be linked to consumption of a brand of imported frozen berries that has been recalled, authorities say.
Ministry for Primary Industries (MPI) director of plant food and environment Peter Thomson said in a statement it was alerted to the case last night following an investigation by the Ministry of Health and Environmental Science and Research.
Mr Thomson said the person ate Fruzio Mixed Berries in late October and reported symptoms at the beginning of this month.
He said the person was briefly hospitalised for observation but released the same day.
The next step is to have the virus tested to see if it is the same strain as that in the four other Hepatitis A cases.
The Ministry of Health is working on this now and expects results at the end of this week or early next week.
MPI had an extensive investigation under way in relation to the outbreak, Mr Thomson said.
"A key focus of this is our continuing forensic examination of the supply chain. Last week, we established an increased surveillance programme, including testing imported frozen berries at the border," he said.
"Given the incubation period can be between 15-50 days, it is not unexpected that a new case of Hepatitis A potentially linked to these berries has been notified."
The advice to those worried about eating imported frozen berries remained the same, he said: briefly boil berries - or cook them at over 85°C for at least one minute - before consumption.
The elderly and those with chronic liver damage should avoid imported frozen berries that have not been heat-treated.