An acute illness caused by food that may be naturally poisonous or contaminated by certain types of pathogenic microorganisms, parasites, or toxins from other sources such as pesticides. The most common type of food poisoning in the UK is that caused by the bacteria belonging to the genus Salmonella, which inhabit the alimentary canal of livestock. Other food poisoning bacteria include Staphylococcus aureus, Clostridium perfringens, Campylobacter jejuni, Listeria monocytogenes, and pathogenic Escherichia coli. Norovirus, found in raw shellfish, also causes symptoms of food poisoning, notably diarrhoea and vomiting. Freezing and other types of food preservation can prevent the growth of the bacteria and thorough cooking will kill the microorganisms before the meat is eaten. However, food poisoning can result if frozen meat is not completely thawed at its centre before cooking, as it may not reach sufficiently high temperatures to kill the bacteria during cooking. Another type of food poisoning, known as botulism, is caused by toxins produced by the bacterium Clostridium botulinum, which can grow in badly preserved canned foods.