What is food poisoning?

​Food poisoning is illness caused by any harmful amount of a natural or contaminating substance in a food, but especially illness caused by some highly infective kinds of bacteria. If not prevented -- as it can be by care and good hygiene -- some kinds of bacteria can grow to large numbers in food and produce toxins (poisons) some of which are difficult to destroy by cooking. Other kinds can cause illness by growing to large numbers in the digestive system. Symptoms include abdominal pain, diarrhoea and vomiting, and may last from a few hours to a few days. In extreme cases food poisoning can prove fatal, especially to babies, the elderly and others with weakened immune systems.