J Korean Med Sci.  2023 Apr;38(15):e117. 10.3346/jkms.2023.38.e117.

The Epidemiological and Clinical Characteristics of the Largest Outbreak of Enterohemorrhagic Escherichia coli in Korea

  • 1Division of Infectious diseases, Department of Internal Medicine, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea
  • 2Division of Disease Control Policy, Gyeonggi Provincial Government, Suwon, Korea
  • 3Korea Disease Control and Prevention Agency, Cheongju, Korea
  • 4Gyeonggi Infectious Disease Control Center, Suwon, Korea
  • 5Division of Biostatistics, Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul, Korea


The largest outbreak of enterohemorrhagic Escherichia coli (EHEC) O157:H7 occurred at a preschool in South Korea from June 12 to 29, 2020. This study aimed to analyze the epidemiological and clinical characteristics of EHEC infection in this outbreak.
Epidemiological investigation was performed on all 184 children and 19 workers at the preschool using a standard questionnaire to assess symptoms, food intake, attendance, and special activity history. Pulsed-field gel electrophoresis analysis of confirmed cases was performed to determine genetic relevance.
During this outbreak, 103 children were affected, whereas only one infection was identified in adults. Of the 103 pediatric patients, 85 had symptoms (82.5%), including diarrhea, abdominal pain, bloody stool, fever, and vomiting. Thirty-two patients (31.1%) were hospitalized, 15 (14.6%) were diagnosed with hemolytic uremic syndrome, and 4 (3.9%) received dialysis treatment. Pulsed-field gel electrophoresis analysis identified 4 genotypes with high genetic relevance (92.3%). Epidemiological investigation revealed that this outbreak might have occurred from ingesting foods stored in a refrigerator with a constant temperature above 10°C, which was conducive to bacterial growth. Despite several measures after outbreak recognition, new infections continued to appear. Therefore, the preschool was forced to close on June 19 to prevent further person-to-person transmission.
Our findings from the response to the largest outbreak will help prepare countermeasures against future EHEC outbreak.


EHEC; Outbreak; Transmission; Epidemiological Investigation; Food Poisoning; Children; Gyeonggi-do; Korea


  • Fig. 1 Floor plan of preschool A.

  • Fig. 2 Epidemic curve of enterohemorrhagic Escherichia coli O157:H7 cases based on symptom onset at preschool A (n = 85, total symptomatic cases).

  • Fig. 3 Pulsed-field gel electrophoresis patterns of enterohemorrhagic Escherichia coli O157:H7 strains associated with the outbreak.


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