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Shiga toxin-producing e. coli (STEC) infection

Information for Local Health Departments

Shiga toxin-producing Escherichia coli (STEC) are important enteric pathogens that can cause severe gastrointestinal infection, which can be complicated by hemolytic uremic syndrome (HUS). HUS is a syndrome consisting of hemolysis of red blood cells and kidney injury, and is a potentially life-threatening condition mostly impacting young children. STEC infections in California have increased in recent years, from about 500 infections in 2011 to over 2,000 infections in 2019, which may be due in part to better detection via culture-independent diagnostic testing (CIDT). There may be many more undiagnosed cases of STEC infection each year in people who did not seek medical care or did not submit fecal specimens for testing.

The most widely recognized STEC serogroup is O157; however, numerous other STEC serogroups, which are often grouped together as non-O157, are common. In fact, non-O157 STEC infections account for approximately 65% of all STEC infections reported in California. In recent years, California patients have been involved in STEC outbreaks due to food or drink contaminated by animal feces, including:

      • ground beef and other beef products

      • unpasteurized milk and apple juice/cider

      • flour

      • leafy green produce including lettuce, spinach, and sprouts

California patients have also been linked to contact with livestock and exposure to contaminated recreational water. Person-to-person contact in families and childcare centers due to poor personal hygiene and inadequate hand washing can cause further transmission. While most STEC infections appear to be sporadic rather than outbreak-related, it is important for local health departments (LHDs) to follow up with patients with STEC infections to identify any potential actionable sources of infection.

Interviewing Patients

  • It is important to interview patients as soon as possible after they are identified for more accurate recall of food and other exposures.

  • Please use the CDPH STEC and/or HUS case report form (CalREDIE tabs or CDPH 8555 PDF in the CalREDIE Document Repository).

Healthcare providers are required to report cases of STEC infection to the LHD within one working day of identification or immediately by telephone if an outbreak of STEC or case of post-diarrheal HUS is suspected. Clinical laboratories are required to submit clinical STEC isolates or Shiga toxin-positive specimens to a local public health laboratory or the California Department of Public Health Microbial Diseases Laboratory for serotyping and molecular subtyping. Please follow up with the clinical laboratory to make sure that the isolate has been appropriately submitted, and document the final laboratory reports in the STEC case report form (either in CalREDIE or in the hardcopy version). Due to the low infectious dose of STEC, LHDs may need to restrict the activities of persons with STEC infection from certain work or activities (such as food handling, health care, or day care) until they have been examined and cleared by their LHD. All patients with STEC infection should be educated regarding disease transmission and appropriate infection control measures.

For detailed information about reporting and STEC infection and/or HUS case investigation guidelines, please see:

CDPH Infectious Diseases Branch (IDB) Guidance for Managing Shiga Toxin-Producing Escherichia coli (STEC) and Hemolytic Uremic Syndrome (HUS) (PDF)

Updated March 2021

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