Some 40 patients at three health facilities supplied by North Shore Hospital's kitchen have been hit by a stomach infection.

A hospital spokesman, Errol Kiong, said this afternoon that patients had been affected at the hospital, and at two mental health units: the Mason Clinic and Taharoto.

The outbreaks of vomiting and diarrhoea began on Sunday evening. The illness appeared to be of quite short duration. "The patients are recovering. Most of them are back to normal."

Mr Kiong said Auckland Regional Public Health Service staff were trying to identify the reason for the outbreak.


"We think it may be related to food somehow. We don't have any confirmation on that."

"The reason we think it's food is because the supply chain for all three areas is from the same place. The food is prepared at North Shore Hospital."

However, Mr Kiong said the outbreak was not related to the listeria outbreak reported in Hawkes Bay last week.

Two women died in Hawkes Bay Hospital after contracting the disease in June while another person died of listeria in the Bay of Plenty this month

Test results showed traces of the bacteria in ready-to-eat meat products supplied to the Hastings hospital.

Napier company Bay Cuisine - the sole supplier of ready-to-eat meats to the hospital - issued a recall notice for several products that may contain the bacteria.

Mr Kiong said: "We don't use any of those meat products identified as part of that recall last week."