Each year about 200,000 New Zealanders get sick from bugs in food. We have a higher rate of food poisoning than other developed countries, and it costs us more than $86 million a year. It’s always an inconvenience, but often it is serious for the very young, elderly and those with poor immune systems.

Something as innocent-looking as a cheese and ham sandwich on a hot summer’s day can mean food poisoning by bacteria you cannot see or smell.

Almost half of those who get food poisoning are thought to get it from poor food handling at home. All harmful bacteria needs to grow is food, moisture, warmth and time.

The usual bacterial cause of food poisoning is campylobacter, which is more common in New Zealand than other countries, and no one knows why.

The other causes are salmonella, E. coli, Staphylococcus aureus and listeria, which is destroyed by cooking but grows on fridge food and is dangerous for pregnant women. (For more info see: Listeria risk in pregnancy)

With Christmas catering and the BBQ season coming, it is time to talk tactics – the four Cs: clean, cook, cover and chill. These simple hygiene rules might save you a lot of embarrassment.

“The last thing we want is to send our guests home with an upset stomach instead of memories of great times, good food and fun people,” says New Zealand Food Safety Authority microbiologist Dr Roger Cook.

Clean your hands, utensils and food surfaces often, particularly before touching food, after handling raw meat or poultry, after using the toilet or changing nappies. Wash and dry them well, as wet hands spread more bacteria.

Avoid using utensils and plates for uncooked then cooked foods, and contaminating the cooked food. It is best if you clean up as you go along.

Cook foods well. Undercooked chicken is a danger – try flattening larger chicken pieces with a rolling pin for more even cooking. When cooked, all poultry juices should run clear, not bloody. Cooked sausages and mince patties should not still be pink in the middle.

Covering foods is important. Only uncover them when you are actually eating. This helps keep insects off food, and keeps raw food, juices and cooked foods separate.

Chilled foods, ready-to-eat or pre-prepared, should be kept cold at 2 to 4 degrees Celsius. You might need to check your fridge temperature. This includes ready-to-eat cooked meats, seafood, pates and foods such as custard, coleslaw, mayonnaise, rice and pasta salads.

If not eaten immediately, freshly cooked food needs refrigerating. Frozen foods need thawing thoroughly in the fridge or by microwave. Do not reheat food more than once.

If you do succumb to a bug, it is likely to strike three hours after eating, maybe 10 hours for campylobacter. You can expect diarrhoea, stomach cramps, nausea, vomiting and fever.

To get over it, drink plenty of water or electrolyte solution from a pharmacy. Stick to plain foods and keep off dairy products until you feel better.

Get medical advice early for elderly people, for those with medical conditions and for young children and babies.

Also visit PharmacyLive for information on pharmacy products available for diarrhoea.

(Published in the Sunday News, 13 December 2009)

More everybody MYHEALTH columns from Barbara Docherty

Barbara Docherty is a registered nurse and clinical lecturer at the University of Auckland School of Nursing, and writer for the everybody.co.nz website. The opinions contained herein are those of the author and not necessarily those of the publisher or sponsor. Copyright UBM Medica (NZ) Ltd.