Food poisoning – how to avoid and how to treat

Nothing ruins a summer holiday quicker than a tummy bug. The vomiting, diarrhoea and stomach cramps that come with a bout of food poisoning (gastroenteritis) can really lay you low for a few days – and sometimes even longer, for up to a month. Food or drinks can be contaminated with bacteria (or the toxins secreted by bacteria), viruses or parasites that cause gastroenteritis. Symptoms can start as quickly as an hour after consuming the bug, but generally the symptoms turn up around 12 to 72 hours later. E. coli, Salmonella, Shigella, Campylobacter and Listeria are common culprits of bacterial gastroenteritis. They can be found in raw or undercooked meat, poultry and seafood, and unpasteurized milk. They account for about 80% of travellers diarrhoea. Parasites such as Giardia and Cryptosporidium are often found in untreated water. Viruses such as Norovirus and Rotavirus also cause gastroenteritis. In New Zealand children receive a vaccination for Rotavirus as part of their 6-week and three-month vaccinations, however, there is no vaccine for Norovirus.

People of all ages can be affected by gastroenteritis but it is particularly common in young children and this age range is more susceptible to dehydration. While it is a very unpleasant condition people are usually able to look after themselves and/or their family members at home. You need to stay away from work, school and early childhood centres until at least 48 hours after symptoms have cleared.

Food poisoning symptoms are fairly predictable. When the stomach and intestinal tract become inflamed by infection the body responds with sudden watery diarrhoea, nausea and vomiting (often projectile!), abdominal pain and cramps. Sometimes there can also be a mild fever, and less commonly headaches and aches and pains can occur.

Simple hygiene practices and correct food preparation and storage are very effective at preventing food poisoning:

  • Wash hands after going to the toilet and before eating or handling food.
  • Drink bottled or treated water only.
  • Eat hot food – meals served steaming hot are safest because high temperatures can kill any organisms present.
  • Store food properly to prevent it from spoiling.
  • Defrost frozen meat correctly, either in the fridge or use a microwave rather than leaving it on the bench.
  • Put grocery meat away immediately.
  • Chill, prepare and cover poultry correctly – store it in containers, fully defrost before cooking, keep separate from other foods, wash hands often when preparing, and make sure it is fully cooked (juices run clear).
  • Keep all raw meat well separated and covered from other foods and use separate chopping boards for meat and fruit or vegetables.

The most important part of treatment for food poisoning is staying hydrated. A lot of fluid is lost from the body with all the vomiting and diarrhoea, and this fluid needs to be replaced. Water and oral rehydration therapy (ORT) are best but diluted fruit juice, soups and ice blocks are good alternatives. Paracetamol can be given to treat any aches, pains or fever and loperamide is a medicine that slows down the activity of the gastrointestinal tract and is very good for stopping diarrhoea. Rest is important for recovery and once people feel like eating again, very plain food such as soup, bread and pasta is more easily tolerated.

You will need to seek medical help if you or the person you are caring for shows signs of severe dehydration. These signs are dizziness, passing no or very small amounts of urine or losing consciousness. Severe cases of dehydration may need to be treated in hospital with iv fluids. Other symptoms such as blood in the diarrhoea, recent travel, a fever above 38 degrees Celsius or if the patient is unable to stop vomiting or cannot hold down any fluids are all reasons to be checked out by a doctor.

This blog provides general information and discussion about medicine, health and related subjects. The information contained in the blog and in any linked mate­ri­als, are not intended nor implied to be a substitute for professional medical advice.

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