The rotten link in the food chain

21:38, Feb 17 2009
WELLY BELLY: New Zealanders should take extra care in the summertime to avoid getting food poisoning.

New Zealand has one of the highest rates of food poisoning in the developed world, and summer is when the nasties are most prevalent. Kimberley Rothwell looks at the evil bugs lurking in our summer foods.

It was just an innocent little ham sandwich. Made on Vogel's toast slice bread, with a little olive oil spread, a little wholegrain mustard, nothing too fancy. But in it lurked something nasty, something cruel, as 36-year-old Che Tibby discovered when he ate it for lunch one warm October day.

"It was probably by evening that I started to get . . . a feeling of urgency," he says diplomatically. "There was a mass evacuation – it was like people leaving the Twin Towers on 9/11."

He should have known better. He should have known, after working in kitchens, that taking wafer cut ham from the freezer, leaving it on the sink bench on a spring day and then putting it in the fridge while it was slightly warm, was a bad idea.

"Normally what I'd do is just drop it on cold water and that defrosts things pretty quickly, but in this case I was in a hurry and I left it on the bench and went out. So when I got home the ham was just a tad warm. I thought, she'll be sweet as, and I just fired it straight into the fridge. It looked a little greasy but it wasn't bad."

That night he drank water and ate white bread to quell his diarrhoea, but the next day at work his colleagues sent him home. "People told me I looked like death."


"I wasn't necessarily sick, I wasn't dehydrated so I didn't hallucinate too much but my eyes were definitely swimming."

Che's case was one of the 200,000 cases of food-borne illnesses New Zealanders come down with each year. Almost half of those are caused by unsafe food handling at home.

New Zealand's rate of food poisoning is considerably higher than other OECD countries. World Health Organisation figures show there were 271 cases of campylobacter poisoning – the heavyweight of food-borne illnesses – per 100,000 people in 2001, compared to the next highest, Australia, with 107 cases.

According to the New Zealand Food Safety Authority (NZFSA), in 2005 there were nearly 14,000 cases of campylobacter poisoning in this country, with 871 hospitalisations. Caused by undercooked chicken, unpasteurised milk, chicken liver pate and infected drinking water, it can give sufferers diarrhoea, muscle pain, headaches, fever, abdominal pain and nausea. It can be fatal – over nine years there have been 11 deaths associated with the disease.

Other nasties to beware of include listeria, e coli, salmonella and staphyloccocus aureus, most of which flourish in meat, poultry, eggs and dairy products at temperatures of between five to 60 degrees celsius.

We often forget bacteria lurking in things like custard, coleslaw, mayonnaise and icecream if not stored correctly.

And then there's bacteria in rice, the risk of nasties getting transferred from high risk foods to your salad and other raw foods, bacteria on your hands, flies making trips from the rubbish to your immaculately prepared al fresco meal – it's enough to make you wonder if anything you eat is safe.

Medical officer for health Annette Nesdale says it can be hard to find the cause of a case of food poisoning – meat may be cooked perfectly on the barbecue but could have leaked blood in the fridge on to something else while still raw, or bacteria could linger in chopping boards used for raw meat then used for making salad, for example.

"We wish we had better data," she says. "We know in New Zealand we have higher campylobacter rates than other countries but the exact cause isn't known."

She points out that over the summer months, something as simple as an overloaded fridge where cross- contamination can occur, or groceries bought and left in a hot car for hours on end can lead to a nasty bout of food poisoning.

Donald Campbell, principal adviser of public health at NZFSA, says not all cases of food poisoning can be blamed on the consumer handling the food unhygienically, but vigilance is still important.

"There's a whole chain of things that really have to go wrong – but certainly good hygiene is the end barrier that can help protect you. It's just the same as you're not safe crossing the road, but if you go at the traffic lights and follow the green man, your risks are remarkably reduced."

He says the reason for New Zealand's high rate of food poisoning isn't known.

"Some of it could be related to good reporting, some could be differences in agricultural practices. It could be different eating habits. It's a combination of things.

"There is some evidence that we have different strains of bugs. Say for campylobacter, there's some evidence we have some strains here that other countries don't have. For salmonella it's vice versa. There's a strain that was a major problem in Europe quite a while ago to do with eggs, but we've never had it here."

Even something as seemingly harmless as rice can be toxic. Cooked rice can develop bacteria if left between five and 60C, so unless it's going to be kept hot or eaten straight away, it needs to be put in the fridge immediately. It's the same with defrosting foods – you don't want them going above 5C before they are cooked, so keep them in the fridge till you're ready to cook.

Food technology teacher Helen Milner says the best thing you can buy someone for Christmas is a digital thermometer for making sure food is cooked properly. She says 75C is a safe temperature for food to be cooked at, but few New Zealanders know that. Or know how to keep themselves safe.

She's particularly concerned about what kids take to school for lunch. Food sitting around in warm lunch boxes is a perfect breeding ground for bacteria, and she recommends replacing the old box with a chilly bag.

Barbecues are another danger zone – especially mince and chicken. She teaches her students to flatten mince patties as much as possible, as bacteria cover the surface of the meat that has been exposed to the air.

As even the centre of a mince pattie has been exposed to the air at some stage, it needs to be cooked properly to kill the bacteria living on it. For chicken, which has bacteria in all parts of the meat, she recommends using a rolling pin to flatten it to get heat to the centre, or better still, cook it in the oven or microwave first.

And don't get her started about tongs. Ideally barbecue cooks should have more than the usual one pair – different pairs should be used for handling raw meat and cooked meat.

You don't want bacteria in the blood of uncooked meat getting on to your ready-to-eat perfectly cooked steak. It could ruin your summer, and nobody wants to spend sunny days hunched over the toilet with only their own body fluids for company.

How to avoid getting food poisoning:
* Wash hands thoroughly for 20 seconds and dry them for 20 seconds after gardening, going to the toilet, changing nappies, or handling pets, money or rubbish.

* Keep kitchen bench tops clean, and wash knives, chopping boards and utensils.

* Ensure your fridge is operating between 2C and 4C. Many pathogens flourish at 5C to 60C.

* Keep perishable food in the fridge till you're ready to use it. Keep raw meat and poultry covered and away from ready to eat foods, fruit and vegetables.

* Defrost or marinate meat in the fridge, not on the bench top. Throw away any leftover marinade.

* Make sure mince and sausages are cooked right through – not pink the middle. Pork and poultry juices should run clear.

* Don't leave food uncovered or at temperatures over 5C for more than two hours.

* The only time food should be uncovered is when you're eating it.

* When barbecuing, pre-cook mince and chicken before cooking on the barbecue, don't use the same plate to transport raw and cooked foods. If you're eating outside keep food covered to protect it from flies and insects till you're ready to eat.

* Pop leftovers into the fridge or freezer within two hours of their preparation. Don't reheat them more than once and eat within two days.

* When cooking rice to be eaten cold, cool it immediately after cooking it and keep it in the fridge. Toxin-forming bacteria will grow on rice if it is cooled slowly, and reheating it will not kill the spores.

The Dominion Post