NZ food - it's enough to make us sick

By SIMON COLLINS


New Zealand's food-poisoning rate is the highest in the developed world - and no one knows why.

The number of cases of campylobacter alone leapt by 18 per cent last year to a record 14,786 cases.

Last year's figures for other countries are not yet available, but New Zealand's rate of 368 cases for every 100,000 people last year was almost five times Australia's rate in 2002 and almost 10 times the rate in Canada.

Dr Rob Lake of the Institute of Environmental and Scientific Research (ESR), which compiled the figures, said the New Zealand food-poisoning rate was the highest known in any developed country, but no one knew why.

Auckland Medical Officer of Health Dr Greg Simmons said it was "a $40 million question".

That was the estimated cost of campylobacter in terms of days off work, medical treatment and other costs to the country.

The total cost of all foodborne illnesses was estimated at $55 million, including almost 500,000 sick days, counting the expected rate of minor, unreported cases as well as those severe enough to be reported by doctors.

An ESR report published last year said campylobacter was "a potential epidemic". But the figures are so much higher than other countries no one is sure what to make of them.

The leading suspects are reporting procedures, contact with animals, poultry industry hygiene and the Kiwi lifestyle.

* REPORTING PROCEDURES vary widely. Campylobacter is not a reported illness at all in New South Wales, and in the United States figures are collected in only about a dozen states.

In New Zealand, campylobacter has been reported only since 1984, and figures for the 1980s are believed to be understated because it took a while for doctors to get used to reporting them.

But Dr Simmons said New Zealand reporting procedures had been stable since about 1990. Yet the rate of campylobacter has more than trebled since then.

* ANIMAL CONTACT can cause campylobacter in rural areas. A study in the Ashburton district two years ago found that exposure to the faeces of animals such as cows and sheep was probably responsible for most cases of the disease in humans.

A 2001 study found that campylobacter was present in 60 per cent of New Zealand rivers and shallow ground water.

* POULTRY is the main source of campylobacter in the New Zealand diet. ESR's summary says campylobacter rates in various studies ranged from zero in one sample of frozen chickens up to 57 per cent in whole fresh chickens.

It found most outbreaks were caused by undercooking chicken - "in effect, eating raw poultry".

After loading all possible factors that might cause the disease into a computer, it found that chicken alone accounted for outbreaks more than all other factors combined.

New Zealand's chicken consumption more than doubled in the past decade, from about 15kg per person each year to 36kg.

ESR said strict hygiene controls at all poultry houses had cut campylobacter rates in Scandinavia. Similar measures had been taken in New Zealand to control salmonella, but not specifically for campylobacter.

But the executive director of the Poultry Industry Association, Michael Brooks, said New Zealand's hygiene and biosecurity standards were "as high as anywhere in the world".

He said New Zealand's chicken consumption was almost identical to Australia's and slightly below the US, yet both countries had much lower human campylobacter rates.

* THE KIWI LIFESTYLE may be another factor. The Food Safety Authority's principal food safety/microbiology adviser, Dr Roger Cook, said the barbecue was a New Zealand institution.

"New Zealanders take stuff to a barbecue in the car and it might sit in the car for a few hours until it's eaten. Then they're eating left-overs for the rest of the day," he said.

The disease is highly seasonal, peaking in summer. Unlike many other diseases, it is more common in Europeans (387 for every 100,000 people) than in Maori (134), Pacific people (88) or others (240).

It is also more common in temperate climates.

ESR concluded that people could minimise the risks by safe food handling, such as washing hands, cooking poultry thoroughly and storing it in chilled conditions.

But as yet, the causes of New Zealand's high rate remain a mystery. As Dr Simmons put it: "The simple answer is we don't know why."