Food poisoning is a general term for infections contracted through food. Typical symptoms of food poisoning include stomach cramps, diarrhoea, nausea and vomiting. Bacteria are the most common cause of food poisoning, followed by viruses and parasites.
There are several hundred food-borne diseases, many of which cause other symptoms besides food poisoning. Poisonous chemicals that get into food can also make you ill.
People with HIV/Aids or other immune suppressive diseases are particularly vulnerable to infections from germs in food and water, and need to take extra care. You can’t always tell if food or water is contaminated by how it looks, tastes or smells, but you can greatly reduce the risks by following the simple steps outlined below.
The table below lists the micro-organisms most commonly associated with foodborne illness and examples of foods that are typical vehicles for those illnesses:
|CAUSE||FOODS MOST OFTEN ASSOCIATED WITH THE PROBLEM|
|Bacillus cereus||Reheated cooked rice, cooked meats, starchy puddings, vegetables and fish.|
Improper handling after cooking is a common feature of foods causing B. cereus associated foodborne illness.
|Clostridium perfringens||Reheated foods including buffet dishes, cooked meat and poultry, beans, gravy, stews and soups.|
|Clostridium botulinum||Improperly canned (home-preserved) foods such as vegetables, fish, meat and poultry.|
|Salads and raw vegetables, undercooked meat, cheese, unpasteurised milk.|
|Campylobacter jejuni||Raw milk, poultry.|
|Listeria monocytogenes||Unpasteurised milk and milk products such as soft cheeses, raw meat, poultry, seafood, vegetables, paté, smoked meat and fish, coleslaw.|
|Salmonella||Undercooked poultry, meat, shellfish, salads, eggs and dairy products.|
|Staphylococcus aureus||Ham, poultry, eggs, ice-cream, cheese, salads, custard and cream-filled pastries and gravies, are the most common sources. Improper handling of food or poor hygiene could help S.aureus spread into food.|
|Vibrio parahaemolyticus and other marine Vibrio||Raw and undercooked fish and shellfish.|
|Trichinella spiralis||Undercooked pork or game.|
|Toxoplasma gondii||Undercooked meat and poultry and raw milk.|
|Hepatitis A virus||Shellfish, raw fruits and vegetables can be the uncommon cause of hepatitis A. Hepatitis A can be spread by contaminated food handlers inadvertently transferring the virus to the food they handle.|
Source: The European Food Information Council (www.eufic.org)
- Wash your hands regularly and thoroughly with soap and water, particularly:
- after going to the toilet
- after touching animals
- after sneezing or blowing your nose
- before and after food preparation
- after touching raw meat, fish or poultry
- Try to avoid coming into contact with animal faeces. If you do, wash your hands very well - with anti-bacterial soap if possible.
- Cover wounds on your hands to prevent contamination when working with food. Make sure bandages or plasters are clean. Rubber gloves are useful for keeping both wounds and food clean.
- Boil drinking water first if you are unsure about whether it is safe to drink. Tap water is usually safe, but water from other sources, such as rivers and wells, is not. If boiling isn’t possible, treat the water with bleach, as follows: Mix 1 teaspoon (5ml) of bleach with 25 litres of water (a large basin-full). Leave it to stand at least two hours before drinking.
- Store safe water in a clean, covered container, preferably in the fridge.
- Make sure cold drinks and ice cubes have been made with safe water.
- Remember not to swallow unsafe water while bathing or swimming.
- Buy foods in amounts that can be eaten before they go off.
- Don't buy or use dented, bulging or leaking cans.
- Pre-packaged, sealed cold meats and cheeses are safer.
- Don't buy cracked eggs: the cracks allow germs to enter.
- Don't buy foods after their “sell by” date. Throw out foods at home that have reached their expiry date, and don't even taste food if you suspect it has gone off.
- Avoid foods that have been home-bottled.
Choosing, preparing and storing food
- If you’re not sure where food comes from or how it’s been prepared, don’t eat it.
- Keep food away from animals.
- Cover food to keep insects off it.
Fruits and vegetables
- Peel fresh fruits and vegetables or wash them with clean water.
- Throw out moldy or rotten fruits or vegetables.
Milk and milk products
- Use pasteurised milk. (Milk is heated to high temperatures to destroy germs.) Home-produced milk should be boiled before use.
- Throw out moldy cheese. Avoid cheeses that contain live molds, like blue cheese, Brie and Camembert.
- Don't eat wild mushrooms, unless you are absolutely sure they are safe.
- Never eat raw meat, poultry or fish.
- Cook meat thoroughly. (It shouldn’t be pink inside.) Ask to have your meat well done when eating at restaurants or friends’ houses.
- Avoid seafood that does not come from a known, safe source.
- Never eat raw eggs. Cook eggs until the white and yolk are firm.
- Don’t use cracked eggs.
- Wash eggs before breaking them.
- Food should be kept either hot or cold. Keep cold foods cold:
- Keep frozen foods frozen until you’re ready to eat them.
- Pick up frozen foods last, and hurry home with them or pack them with ice in a cooler bag.
- Don’t keep foods in your freezer longer than a month.
- Once food has defrosted, it should be used as soon as possible, and not refrozen.
- Don’t defrost frozen meat at room temperature, which is warm enough to give germs the chance to grow. Defrost frozen meat or other frozen foods in a fridge. If you don’t have a fridge, defrost food in a cool place. Microwave ovens are also good for quick defrosting.
Keep hot foods hot:
- Eat food as soon as possible once it’s been cooked. Don’t store foods that have cooled down at room temperature.
- Don't keep food at room temperature for more than two hours. After this time period, bacteria start multiplying. Be suspicious of cold cooked food that has been kept at room temperature for longer.
- Refrigerate leftovers. If you don’t have a fridge, keep food covered in a cool place.
- Store foods in airtight containers or cling wrap.
- When you eat cooked leftovers, reheat them to a high temperature to kill germs.
Take extra care when travelling: you are likely to come into contact with new germs that your body isn’t used to.
- Only drink bottled or boiled water, or canned drinks. Avoid ice in drinks, unless you know it has been boiled first.
- Don’t eat raw fruits and vegetables unless you have peeled them yourself.
- Make sure that food has been properly cooked.
- Don’t eat food sold by street vendors.
- Wash surfaces like the kitchen table, counter or sink, before and after preparing food there. Keep food storage areas (like shelves and fridges) clean.
- Clean up spills immediately.
- Use separate cleaning cloths for the kitchen and other parts of the house.
- Disinfect kitchen cloths, sponges and scourers with bleach, and dry them in sunlight, which helps kill germs. If you have a microwave, heating cloths and sponges for 60 seconds helps kill bacteria.
- Wash the kitchen floor at least once a week, with cloths that are only used for that purpose.
- Wash dishes, cutlery and cutting boards well – preferably in hot soapy water that you replace when it gets too dirty. Rinse dishes with clean water, if possible.
- Replace cracked or badly scratched utensils. Germs live in cracks in cups and dishes and scratches in plastic containers and cutting boards.
- Use a cutting board for raw foods. Preferably, use one cutting board for meat, poultry and fish, and another for other foods. Or, clean the board well with hot water soapy after cutting each food type. Plastic or stone cutting boards are safest for raw meat.
- Don’t reuse utensils after they have touched raw meat, fish or chicken, until you have washed them very thoroughly.
- Keep rubbish in a covered bin that you empty and clean regularly.
- Keep the kitchen door and windows open as much as possible to provide good ventilation; this helps prevent the growth of mold and fungus.
- Updated by Olivia Rose-Innes, Health24, June 2011