Everybody at one time or another has had the experience of eating food and some time later becoming sick. This is called food poisoning. The symptoms may include:
- stomach pains
- feeling weak
- fever or chills/sweating
Food poisoning can be caused by eating food contaminated with bacteria, viruses, chemicals or poisonous metals such as lead or cadmium. Most food poisoning, however, is caused by bacteria and because of this, only bacteria will be discussed in this section.
Food which has become contaminated with harmful bacteria does not always taste bad. Most of the time it looks, smells and tastes like it normally does.
Some food poisoning diseases are more common than others. For example, disease caused by Staphylococcus aureus occurs a lot more often than disease caused by Clostridium botulinum.
Some foods cause food poisoning more than others and need to be cooked properly and/or kept in the refrigerator. These include chicken, meat, seafood, eggs, cooked rice, ham, salami, milk and all dairy foods. It is important chicken is cooked properly to the bone and then kept in the fridge for no more than 2 days. If reheating chicken, or left-overs, make sure it is steaming hot and only reheat it once.
Read also: Importance of microbiology in food
It is important to remember that the same food handling practices are used to prevent all food poisoning diseases. Washing your hands with soap and then drying them on a paper towel or with a clean cloth is the best way to stop the spread of bad bacteria.
The common bacteria that cause food poisoning are –
These bacteria are found on the skin, in sores, infected eyes and in the nose, throat, saliva and bowel of humans. There may be many of these bacteria in the yellow mucus (slimy substance) which comes from the nose or is coughed up when a person has a cold or a lung infection.
There are hundreds of different types of salmonella bacteria but not all are harmful to humans. They are found mainly in the intestines, bowels and faeces of humans and other animals. It is the salmonella bacteria themselves which can cause salmonella food poisoning.
People can get salmonella food poisoning from:
- poor food-handling practices in the home or in food outlets
- seafood caught in polluted water or eggs with dirty shells
- meat or poultry which has been contaminated by poor food handling before it gets to the food outlet, such as at the abattoir
These bacteria are found in the soil and in the intestines of animals, including cattle, poultry, fish and humans. Food poisoning caused by clostridium bacteria is important to know about because these bacteria are common in the environment.
People can get clostridium food poisoning from poor food handling practices in the home, in the factory or in a food outlet, especially relating to cooking and storage/refrigeration temperatures.
These bacteria are found in many animals including dogs, cats, cattle and poultry. The sources of infection from these bacteria are usually contaminated food and water.
People can get campylobacter from:
- ingestion of contaminated food or water (especially undercooked chicken & creek or river water)
- contact with infected animals (especially puppies or kittens with diarrhoea)
- poor food handling (especially by using the same chopping boards, knives and plates for raw and cooked chicken)
Ways food can become contaminated through incorrect food handling
Food can become contaminated with disease-causing bacteria anywhere the food is handled or stored. These places include:
- in a factory where it is processed ready for sale
- in a truck in which it is taken from the factory to the shop
- in a shop
- in a food outlet such as a school canteen or takeaway shop
- between the shop and home
- in a home
- Protect food from contamination – handle food properly
- Prevent bacteria from multiplying
- Destroy germs on/in food