Enteric infection has played an important role in the majority of the world's populations, including children (particularly those under four years of age), the aged, the malnourished, military populations, and per- sons from industrialized regions traveling to developing areas. The magni- tude of the problem has been profound in areas of the world with reduced economic development, where there exists a greater reservoir of entero- pathogens and a larger susceptible population with nutritional deficits. Morbidity from enteric infection in developing areas exceeds that seen in industrialized...