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Aug. 20: STEC outbreak

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Outbreak of Shiga toxin-producing E. coli O157:H7 infections among King County residents from East African Communities

Health advisory

August 20, 2022

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  • Be aware of an outbreak of Shiga toxin-producing E. coli (STEC) O157:H7 infections among King County residents, currently all from East African Communities. At least three children have developed hemolytic uremic syndrome (HUS).

  • Consider STEC infection in people of all ages, particularly from East African Communities, who have bloody diarrhea and in people with any diarrhea and a history of any of the following within the 10 days prior to onset of symptoms:
    • Consumption of high risk foods (e.g., raw or undercooked meats, raw produce, unpasteurized dairy or juice products)
    • Animal contact (particularly farm animals – cows, goats, sheep, etc.)
    • Known exposure to someone else with STEC
    • Social event or gathering

  • Obtain a stool specimen in patients with compatible symptoms and request E. coli testing by culture and Shiga toxin.
    • If bloody diarrhea is present, laboratory evaluation should include a complete blood count, blood smear, serum electrolyte panel, BUN, and creatinine. 
    • Shiga toxin immunoassay or PCR should be obtained in addition to culture, but should not replace culture on sorbitol MacConkey agar plate.

  • Obtain the following history about risk factors during the exposure period (1-10 days preceding symptom onset):
    • Group events with food or animals
    • Travel with dates and destinations
    • Other known ills
    • Attendance in a childcare center

  • Counsel patients with suspected or confirmed STEC to stop working in or attending childcare or preschool, or working in food handling or healthcare until cleared by Public Health.

  • Encourage patients to respond when Public Health contacts them directly to ask about potential sources of their infection and to provide further guidance as indicated.

  • Report confirmed & suspected STEC cases to Public Health immediately at (206) 296-4774.

Seven cases with a matching strain of STEC O157:H7 have been reported in King County residents from East African communities, ranging in age from 11 months to 35 years old; 5 cases occurred in those under 15 years of age. Six cases have been reported since late June 2022 and all 7 match by genetic sequencing. Five cases have been hospitalized, and 3 children have developed HUS. No deaths have been reported. We are investigating an additional 2 cases potentially linked to this cluster that are pending confirmatory testing at the Washington State Public Health Lab. We have not yet identified any foods, restaurants, or other sources in common among all cases. The investigation is ongoing.

Anyone ill with suspected or known STEC should not work in or attend childcare or preschool, or work in food handling or healthcare until cleared by Public Health. We will work with the cases directly to help them with clearance testing when indicated for return to work or childcare.

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