John Key wants answers over listeria outbreak

Prime Minister John Key is demanding answers in the wake of the deaths of two elderly Hawke's Bay women from listeria, traces of which were found in meat supplied to Hawke's Bay Hospital.

Four cases of the notifiable disease have occurred in hospital patients here - two women aged in their 60s and 80s died and two have recovered after contracting the disease in May and June.

Mr Key said last night a "thorough investigation" was needed to establish the cause of the outbreak. Its source has not yet been confirmed, but tests show traces of the bacteria in ready-to-eat meat supplied to the hospital.

Napier company Bay Cuisine - the sole supplier of those products to the hospital - issued a recall notice for products they said may contain the bacteria.

The Minister of Health had sent a letter to all DHBs asking them to check their food safety policies.

A Ministry of Primary Industries spokesman said an end-date to the investigation was unknown.

"MPI cannot put a timeline on that. MPI's first priority is to ensure any unsafe food is not available for sale and that people do not eat any of the recalled products they may have already bought," he said.

"MPI has had about 20 people working in the response team. This number has included around 12 fulltime staff and other part-time staff where necessary."

Hawke's Bay District Health Board infectious disease physician Andrew Burns said the disease had an incubation period of up to 70 days, making it hard to determine how it was contracted.

Lengthy testing processes explained the delay between patients presenting in May and the outbreak being confirmed only this week, a spokeswoman said.

"There are a number of steps that need to be taken to confirm that firstly the person has listeria and then, when there is more than one case, that there is a common link," she said.

A common link was not discovered until Monday, after the MPI conducted DNA fingerprinting.

"This was the first time Hawke's Bay DHB could be confident that these cases could be considered as an outbreak as they showed strains that suggested a common link."

Bay Cuisine voluntarily recalled ready-to-eat products that might be affected from Mad Butcher and Prestons stores throughout New Zealand.

The company also supplies products to a range of clubs, schools, rest homes, wineries, bakeries and large food manufacturers, but as directors declined to be interviewed, it is unclear how far the products were distributed.

Population health director Dr Caroline McElnay said the disease was a risk only to pregnant woman, the elderly and those with suppressed immune systems.

Martin Taylor, CEO of New Zealand Aged Care Association, a not-for-profit which represents all parts of the aged-care residential sector, said he was not aware of any risks in the industry.

"I haven't heard of anything, but obviously any care facilities will be very mindful now that they know their supplier has a problem with the quality of their products, and I should imagine every other supplier in the health sector would be checking very carefully what they have bought," Mr Taylor said.

"With the incubation period of up to 70 days, there are quite a lot of elderly people who have short stays in DHB hospital for whatever reason and they will be monitored carefully.

While Bay Cuisine may supply some products to rest homes, it doesn't mean it will be supplying those products [affected by listeria]."