STEC O157 in the beef chain - risk assessment and management.

Abstract

Abstract Since the early 1980s, Escherichia coli O157 has emerged as one of the most significant pathogens of public health relevance not because of the incidence of the illness, which is much lower than that of other food-borne pathogens such as Campylobacter or Salmonella , but because of the severity of the symptoms, the low infectious dose and potential sequelae. Shigatoxin-producing E. coli (STEC) is a human pathogen that can cause haemorrhagic colitis (HC; bloody diarrhoea). This can also develop into haemolytic uraemic syndrome (HUS), a life-threatening disease that causes kidney damage. Cattle carry mixtures of O157 and non-O157 STEC in their intestines which are not necessarily pathogenic to humans. The O157 STEC serogroup was until recently responsible for the majority of disease outbreaks reported for STECs in North America. However, now the non-O157 STECs account for almost 50% of the reported human disease outbreaks in North America and Europe. Most available information relates to serotype O157:H7, since it is easily differentiated biochemically from other E. coli strains. The O157 STECs are shed at significant levels by healthy/asymptomatic cattle, e.g. cattle with jejunal haemorrhage syndrome (JHS). The shedding leads to contamination of the farm environment. This may lead to direct or indirect contamination of cattle hides, which, in turn, can serve as the main source of carcass contamination during slaughter and dressing of cattle at abattoirs or contamination of fresh beef and beef products. A science-based risk assessment is needed to assess the public health impact, the consumer exposure to the pathogen and to propose possible control strategies. In contrast, risk management should include selection of the most effective control measures, for prevention and reduction of the transmission of beef-borne O157 and non-O157 STECs. Since relatively limited STEC reduction was achieved by applying only one control measure (e.g. decontamination treatments of hides/carcasses and/or adequate cooking), a coordinated, targeted and effective application of control measures at multiple points along the beef chain is necessary. Such an integrated approach has a greater potential to manage the risk of beef-borne STEC infections and it should be based upon: on-farm controls, transport-livestock market-lairage controls, slaughter-dressing controls, chilling-processing-retail controls and controls at the catering-consumer level.