Emerging Risk evaluation of Enterohaemorrhagic Escherichia coli on Public Health

Abstract

Enterohaemorrhagic Escherichia coli (EHEC) include serotypes E. coli O157: H7 and some other serogroups. Current epidemiological studies indicate that strains of enterohemorrhagic Escherichia coli (EHEC) belonging to serotype O157:H7 are most commonly associated with severe human diseases. The ability of EHEC to colonize human and animal intestinal mucosa and to cause disease is associated with a number of virulence factors, including expression of Shiga toxins (Stx) and the capacity to induce attaching/effacing (A/E) lesions. Other virulence factors carried by mobile genetic elements like pathogenicity island (PAI) and plasmids have been recently described. EHEC are zoonotic pathogens. They rarely cause disease in animals, and ruminants are recognized as their main natural reservoir. Cattle are the most important source of human infections with EHEC O157:H7. The organism has also been reported in sheep and goats. The epidemiology of EHEC infections has remarkably changed and an increasing numbers of unusual food vehicles have been associated with human infections. New routes of transmission have emerged, like contact with animals during farm visits and a wide variety of environment-related exposures. As for other zoonotic agents, having animals and raw products that are free from EHEC is not possible in practice. However, their occurrence can be minimised by applying high standards of hygiene in all the steps of the food production chain.