Managing Shiga toxin-producing Escherichia coli (STEC) risk in beef: how lack of data impairs risk analysis

Shiga toxin-producing Escherichia coli (STEC) are a heterogeneous group of pathogenic bacteria characterized by harbouring stx genes. STEC are commonly found in the gut of ruminants and the intermittent bacterial shedding through faeces can cause the contamination of meat and dairy products. The high variability in pathogenicity within this group and paucity of effective control measures make assessment and management of STEC along food supply chains difficult. To date, risk assessment of STEC, particularly hazard identification and characterization, is limited by variability, uncertainty and data gaps. In the EU, STEC infections are mainly associated with 'bovine meat and products thereof', 'milk and dairy products', 'tap water including well water' and 'vegetables, fruit and products thereof'. Whereas the lack of data impairs full quantitative risk assessment, semi-quantitative tools can be useful in ranking the effect of mitigation strategies. In this work, Risk Ranger tool was assessed for its potential usefulness for risk managers considering the beef food chain, with beef hamburger as the target product. Due to the lack of correlation between serotypes and disease risk, we suggest that the hazard should be redefined. A STEC classification should be based on virulence determinants and the associated disease burden, in terms of disability adjusted life years (DALY). Indeed, adopting a new STEC classification based on stx-and eae-genes subtypes would allow more precise hazard characterization addressing some of the existing data gaps. While waiting for data following this new approach and enabling full quantitative risk assessments, semi-quantitative approaches can help to identify efficient mitigation strategies.