National Surveillance Data
National laboratory-based surveillance is used to monitor the occurrence of infections caused by Salmonella, Shigella, and Shiga toxin-producing Escherichia coli (STEC) by collecting information on strains of these bacteria that are isolated and identified from patient specimens by clinical laboratories. Isolates of Salmonella, Shigella andSTEC are submitted by clinical diagnostic laboratories to state or territorial public health laboratories. When an isolate is confirmedas Salmonella, the public health laboratory performs serotyping according to the Kauffmann-White scheme. When a Shigella isolateis confirmed, the public health laboratory speciates it. Identification of STEC requires demonstrating the ability of the E. coli isolate to produce Shiga toxin. Because virtually all E. coli O157:H7 strains produce Shiga toxin, identification of both the O and H antigens of this serotype is sufficient to consider it a STEC.
The laboratory-based surveillance systems for enteric disease at CDC include the National Salmonella Surveillance System, the National Shigella Surveillance System, and the National STEC Surveillance System. All of these systems collect laboratory information from state public health laboratories through the Laboratory-based Enteric Diseases Surveillance (LEDS) system. For Salmonella and Shigella isolates, these data have been collected since the 1960s; data on STEC isolates have been collected since 1995. The annual summaries of these data are the only national source of subtyping (species or serotype) information for these pathogens.