N Noah, London School of Hygiene and Tropical
Medicine, London, UK
© 2005 Elsevier Ltd. All rights reserved.
The burden of gastroenteritis (GE) in the world, in terms of both morbidity and mortality, is enormous. In the developing world (e.g., Southeast Asia), diarrhea vies with acute respiratory tract infection as the leading cause of death in childhood. Even in the more developed world, infectious GE is a significant cause of illness and time lost from work, and death does occur. Infectious intestinal disease in England is estimated to cost the country £743 million p.a. (in 1994-95 prices). GE caused by bacteria was far more costly than that caused by viruses. The more sophisticated surveillance systems become, the more GE they uncover.
Not all GE is caused by food. Probably most GE is caused by poor hygiene leading to direct or indirect transmission of infection without the assistance of food. Nevertheless, a major cause of infectious GE throughout the world is contaminated food. The definition of food poisoning (FP) is not straightforward. In essence, FP is an acute gastroenteritis caused by food. Hepatitis A, typhoid, and brucellosis, however, are not usually considered as FP, whereas botulism is, even though it causes paralysis and not GE, as is listeria, which causes septicemia and meningitis.
Bacteria are the most common known cause of FP and, with the possible exception of the Norwalk-like viruses, of GE also. As one would expect, bacterial FP is more common in summer than winter.
Bacteria produce their effects on the intestinal tract either by direct invasion of the mucosa or by the production of toxin. Some of the toxins are produced outside the intestinal tract—in the food; others are formed in the intestine. Some invasive bacteria also produce a toxin in the intestine. This article provides an overview of the bacterial causes of FP.
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