Infections of the Alimentary Canal
A wide range of bacteria, viruses and parasites gain access to the alimentary canal via the mouth. Outbreaks of ‘food poisoning’ at social gatherings are regularly reported. Infections transmitted from animals (zoonoses) are important; Escherichia coli O157 has been transmitted from the intestinal flora of bovines to humans at ‘petting’ farms. In higher-income parts of the world, Campylobacter is the commonest cause of bacterial gastroenteritis, usually acquired from contaminated, undercooked, fresh chicken carcasses. In tropical and lower-income areas of the world, organisms such as Vibrio cholerae assume importance.