Food Poisoning

What Is Food Poisoning?

Food poisoning occurs when a person gets sick from eating food that has been contaminated by unwanted microorganisms or the toxins they produce. This condition is called ‘Food Poisoning’, or more properly, gastro-enteritis. The most common symptoms of food-borne illness include stomach cramps, nausea, vomiting, diarrhoea and fever.

Who Gets Food Poisoning?

Globally, it seems that between one in three and one in four people gets food poisoning every year, so everyone is at risk – simply because we must eat.

Most cases of food poisoning go unreported to health agencies. This is partly because, for normal healthy adults, food-borne pathogens only cause mild symptoms and medical help may not be necessary. In the UK it has been estimated that for every 136 cases of illness in the community; only 23 people will see a doctor, only six samples will be sent to a laboratory for identification of the organism causing the illness, and just one case will be identified.

Food poisoning is much more serious in young children, and in frail and immuno-compromised people. Diarrhoea and vomiting can, for example, cause life-threatening dehydration in babies and young children. About 5,000 people die every year from food poisoning in the USA. Most of these people were probably already vulnerable at the time of the infection. People with HIV are very susceptible to food poisoning because their immune systems are impaired.

It is reported that males suffer more from gastro-enteritis than females. A possible reason for this is because fewer men wash their hands after using the lavatory than women (33% compared with 66%, taking an average of 47 seconds as against 79 seconds).

Why Don’t We Hear About Food Poisoning In South Africa?

In South Africa, food poisoning is a notifiable disease, but the surveillance system is not effective. South Africa reports just a few hundred cases of food poisoning per year, whereas the incidences are more likely to be in the region of hundreds of thousands of cases.

The effective surveillance and reporting systems of the UK, USA and many European countries has the effect of making people aware of the dangers of food-borne disease and of how to take preventative steps. Outbreaks of food poisoning are often covered in the newspapers overseas. South Africans are much less aware of food-borne illness because no public health campaigns are run to ensure that the food we prepare is safe to eat; and there is also little press coverage on the issue.

What Causes Food Poisoning?

Food poisoning is caused principally by bacteria and viruses. Bacteria may grow in the food so that the food, when it is eaten, contains enough bacteria to colonise the gut lining and cause food poisoning symptoms. Other types of bacteria may not grow in the food itself; in those cases the food acts only as a carrier. Dysentery bacteria are usually only carried in food; only a few dysentery bugs are needed to cause severe illness. Diarrhoea-type food poisoning normally takes between 24 hours and 72 hours to set in after the contaminated food is eaten. If you get food poisoning you need to think back to what you have eaten over the last couple of days and not simply blame the symptoms on the last thing you ate.

Viruses never grow in food, but are passed directly from people to food. Children are often affected with tummy viruses and epidemics are common in schools during the winter months, frequently because of lack of personal hygiene.

Some bacteria, particularly one type found in the nose and throat of most adults and nearly all children, can multiply in certain foods and produce a toxin in the food. When the food is eaten, it is the toxin, not the bug, which causes violent vomiting within a few hours of eating the food.

What Foods Carry Microorganisms?

All foods carry microorganisms. Bacteria and other organisms are all around us, in and on our bodies. The vast majority do us no harm and many are beneficial. Indeed some of our most delectable staple foods are made by using microbes. These include bread, wine, beer, cheese yoghurt, and salami. Some foods are more prone than others to be potential carriers of food poisoning organisms. These foods are principally raw meat, poultry, milk, and seafood.

Meat And Poultry

Food-poisoning organisms are often associated with the gut of humans, animals and birds. Therefore, any food that is contaminated with faeces has the potential to make you sick. Meat and particularly poultry are easily contaminated with faeces during the slaughtering and dressing of the meat, so you should treat all raw meat products as if they were contaminated.

Meat and poultry should be stored away from cooked foods in drip-free dishes. Great care should be taken not to cross-contaminate cooked food with raw meat or poultry. Use separate chopping boards and knives and wash your hands when moving from handling raw meat to prepared food. Meat and poultry needs to be well-cooked because cooking destroys food-poisoning organisms and makes it safe to eat.


Milk is another food that has the potential to be contaminated with faeces. (Remember that milk and faeces both come out of the same end of a cow!) Milk is pasteurised for a very good reason. Pasteurisation is designed to kill harmful food poisoning micro-organisms so that it is safe to drink. Never drink un-pasteurised milk and NEVER give it to children. Avoid cheese that is advertised as being made from un-pasteurised milk (this can sometimes be found in ‘health’ stores and produce markets). It has the potential to be unsafe.

Fruit, Vegetables And Salads

With the trend towards healthy eating and the rising consumption of fruit and vegetables, care should be taken if such foods are eaten raw. Obviously if food is grown in the fields and fertilised with manure that has not been properly composted, or fertilised just before harvest, the potential exists for the vegetables to carry food poisoning organisms. Always wash salad, vegetables and fruit well using potable water (i.e. fit for drinking). The cooking of vegetables destroys harmful microorganisms, so fresh cooked vegetables are safe to eat.

If travelling overseas to less-developed countries, it is a good idea to soak fruit and vegetables in Milton’s solution to destroy any harmful microorganisms on the surface. Remember that the water might also be of suspect quality and Milton’s will disinfect it too.


A small percentage of raw eggs can carry food poisoning bacteria in the yolk or white. It is wise not to give children undercooked or lightly cooked eggs. Avoid all home recipes that require the use or raw or lightly cooked albumen and yolk, such as chocolate mousse and mayonnaise.


Since water is a component of most food and drink, we take in large amounts of it every day through what we eat and drink. Both drinking water and water used to prepare food must be safe. Water contaminated with sewerage is extremely dangerous and is a major source of illness, including cholera. If you are away from home and in doubt about the quality of the water, always boil it before drinking. In South Africa the municipal water is of good quality.

F.A.C.S. Scientific Director. 2009.