Foodborne hazards of microbial origin

Foods can serve as vehicles of many pathogenic and toxigenic agents of disease. Bacterial agents comprise three groups: 1) those that grow in the food and produce an active toxin before consumption (e.g., clostridium botulinium); 2) those that merely exist as contaminants in the food but are able to initiate infection when swallowed (e.g., Salmonella spp.); and 3) those that multiply and produce large numbers of vegetative cells in the food, then release an active enterotoxin when they sporulate in the gut. A few parasitic (e.g., Trichinella spiralis) and viral agents (e.g., hepatitis A) also can be transmitted by food. Botulinum poisoning is the deadliest foodborne disease. The potential danger of botulism from cured meats is a major factor in the argument over use of nitrites as meat curing agents. A new disease called infant botulism has been recognized since 1976. Apparently it is not foodborne but results from intraintestinal growth of C. botulinum in very young infants. Salmonellosis is the most important of the foodborne diseases from the standpoint of overall human health. The primary vehicles are contaminated raw meat, poultry, and eggs. Faulty food handling practices are responsible for most food poisoning in the United States.