Significant Threats to Human Health

Shiga toxins represent a significant and evolving threat to human health. Shiga toxin-related illness is not a common foodborne illness, but it accounts for a disproportionately large share of hospitalizations and deaths. The phages that control expression of Shiga toxins can readily undergo recombination and incorporate new genetic information that can be passed on to their progeny. Because Shiga toxin-producing phages can infect bacteria other than E. coli, it is likely that new Shiga toxin-producing bacteria will emerge, such as the Enterobacter strain associated with a recent outbreak. Previous assumptions about pathogenicity have changed and will undoubtedly continue to change in the future. Based on prior research, the ability to attach and efface was considered to be essential for STEC pathogenicity, but the 2011 STEC outbreak in Germany demonstrated that a new strain (O104:H4), without attaching and effacing ability, could cause a major outbreak. New types of Shiga toxins are emerging, such as subtypes Stx2e and Stx2f that have a preference to bind Gb4. Changes in dietary patterns also influence the source and extent of outbreaks. Thus, the nature of the Shiga toxin threat is evolving on four levels: toxin structure, Stx-phages, bacterial serotypes/strains, and patterns of food production and consumption.