Numerous infectious diseases are acquired by the ingestion of contaminated food, milk, or water. Such illnesses have a worldwide distribution, although, predictably, the incidence is greatest in those countries where deficiencies exist in the provision of adequate sanitation and hygiene.

Yet outbreaks of food poisoning and other food-borne infections occur with frequency even in the most developed countries of the world. Here increasing demand for vast quantities of readily available food has been met by increased reliance on intensive farming techniques, industrialization of food production, introduction of various methods for preservation, and expanding networks for transport, storage, and distribution.

Many of the stages involved in the commercial processing and production of food provide ideal opportunities for the entry, maintenance, and multiplication of microbes. Consequently, several outbreaks of food-borne infection occur each year in developed nations, with the size of the outbreak reflecting the extent of the distribution of the product. Containment measures rely heavily upon early diagnosis and close cooperation between clinicians, medical microbiologists, and officials of public-health departments and are aimed at rapid detection of the source of infection and prompt action to curtail the outbreak. The measures taken must include immediate withdrawal of the incriminated article of food from sale to the public, dissemination of clearly worded information to consumers defining the source and mode of spread of the infection, and – where appropriate – guidelines on methods of preventing cross-infection between individuals.

Outbreaks of food-borne diseases occurring in Britain in recent years have included (1) salmonellosis spread via infected poultry meat, powdered baby milk, hens' eggs, imported chocolates, and spaghetti; (2) Escherichia coli infection transmitted through hamburger meat; (3) botulism from yoghurt that was flavored with contaminated hazelnut puree; and (4) listeriosis from soft cheeses. Recognition of the phenomenal cost entailed in the investigation and control of such outbreaks has led to a heightened awareness of the need for effective measures to curtail the incidence of food-borne diseases. Accordingly, recommendations have been formulated for improving the microbiological quality of food. However, the subject is a complex one and problems continue to arise.