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NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

CSTE Position Statement(s)

  • 09-ID-30

Clinical Description

An infection of variable severity characterized by diarrhea (often bloody) and abdominal cramps. Illness may be complicated by hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP); asymptomatic infections also may occur and the organism may cause extraintestinal infections.

Laboratory Criteria For Diagnosis

Isolation of shiga toxin-producing Escherichia coli from a clinical specimen. Escherichia coli O157:H7 isolates may be assumed to be shiga toxin-producing. For all other E. coli isolates, shiga toxin production or the presence of shiga toxin genes must be determined to be considered STEC.

Case Classification


A case of postdiarrheal HUS or TTP (see HUS case definition), or identification of shiga toxin in a specimen from a clinically compatible case without the isolation of the shiga toxin-producing E. coli.


  • A case with isolation of E. coli O157 from a clinical specimen, without confirmation of H antigen or shiga toxin production, OR
  • A clinically compatible case that is epidemiologically linked to a confirmed or probable case, OR
  • Identification of an elevated antibody titer to a known shiga toxin-producing E. coli serotype from a clinically compatible case.


A case that meets the laboratory criteria for diagnosis. When available, O and H antigen serotype characterization should be reported


For users of the legacy National Electronic Telecommunications System for Surveillance (NETSS), laboratory-confirmed isolates are also reported via the Laboratory-based Enteric Disease Surveillance (LEDS) system, formerly known as the Public Health Laboratory Information System (PHLIS), which is managed by the Enteric Diseases Epidemiology Branch, Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC.

Both asymptomatic infections and infections at sites other than the gastrointestinal tract, if laboratory confirmed, are considered confirmed cases that should be reported.

Related Case Definition(s)