Foodborne illnesses are caused by ingestion of foods containing microbial and chemical toxins or pathogenic microorganisms. This chapter concentrates on toxin-mediated syndromes, usually called food poisoning, rather than on syndromes reflecting enteric infection, such as salmonellosis, shigellosis, vibriosis, and Shiga toxin-producing Escherichia coli (STEC) infection. Treatment of these infections is covered in Chapter 49, Gastroenteritis, and in chapters on the specific organisms.

Clinical presentation and diagnosis

Initially, the diagnosis of specific food poisoning syndromes is suggested by the clinical presentation, the incubation period from exposure to onset of symptoms, and the food consumed. The incubation periods, symptoms, and commonly associated foods for specific syndromes are shown in Table 50.1. Incubation periods range from a few hours or less in the case of preformed chemical and bacterial toxins, such as histamine poisoning (scombroid), staphylococcal food poisoning, and Bacillus cereus, to several days for bacterial infections (e.g., Campylobacter jejuni, Salmonella, Yersinia enterocolitica, and E. coli O157:H7 or other STEC) and some types of mushroom poisoning. Therefore, it is essential to obtain a diet history covering 3 to 4 days before the onset of symptoms. A careful history of illness in meal companions may help point to the responsible food. It is clinically useful to consider syndromes grouped by incubation period and symptoms.