Current Status on the Etiology, Epidemiology, Food Safety Implications and Control Measures in Escherichia coli O157:H7 Infections pp. 155-179
Authors: (Normanno G., Department of Health and Animal Welfare-Faculty of Veterinary Medicine, Italy)
Abstract: Escherichia coli O157:H7 is an important foodborne pathogen. It was recognized as a cause of severe human illness only in the early 1980ís. Since then it has been implicated in foodborne disease outbreaks in many countries throughout the world. Cattle are the main reservoir of this microrganism, and transmission of the infection to humans occurs primarily through the consumption of contaminated food. The pathogenicity of E. coli O157:H7 is associated to genes encoding for a number of virulence factors, especially the verotoxin-encoding genes. The infective dose is extremely low - in the order of a few bacterial units. E. coli O157:H7 is acid-tolerant and survives in acidic environments such as the gastric barrier and acidic foods. The most severe illnesses induced by E. coli O157:H7 are Hemorrhagic Colitis and Hemolytic Uremic Syndrome. Both these clinical forms are characterized by severe morbidity and might sometimes be lethal. Children are the most commonly affected age group and they are affected by the highest death rate. E. coli O157:H7 is one of the main food safety hazards having important implications for human health worldwide, since outbreaks lead sometimes to cases of mortality. This review examines the etiological and epidemiological aspects of E. coli O157:H7 infection and focuses on the food safety concerns raised by E. coli O157:H7 and on control methods for the prevention of food poisoning.