Research conducted by University of Calgary scientists informed care when suddenly hundreds of children were sick from exposure to a severe strain of E. coli .
Shiga toxin-producing Escherichia coli (STEC) is a bacterium that can cause bloody diarrhea. One in five infected children experience life-threatening complications. In the summer of 2023, a large STEC outbreak occurred at several Calgary daycare centres.
“This outbreak resulted in 285 children becoming infected. STEC infections can quickly lead to serious health problems that can affect children for life,” says Dr. Stephen Freedman , MD, emergency department physician and senior investigator on the study. “Alberta has one of the highest incidence rates of STEC infection in North America. We had been studying this infection and its treatment for years. When the outbreak happened, we knew that daily laboratory monitoring and treating dehydration could prevent complications and potentially save lives.”
Daily visits to the Alberta Children’s Hospital (ACH) became routine for the Hull family.
“We were extremely impressed at the efficiency of the process and the personal care we received,” says Kirrily Hull. Her son, Hank, was three years old when he tested positive for STEC. “Hank’s blood was taken and analyzed daily. Each time a doctor would go over the results with us. The care process was organized, and everyone knew what needed to be done. We were very thankful for this.”
For some children, the tests indicated that complications were beginning to occur before they became obvious, clinically. Those children would be admitted to hospital and monitored for development of hemolytic uremic syndrome (HUS), a condition that can impact many organs and often results in kidney failure requiring dialysis. Unfortunately, one to three per cent of children with HUS die.
“At the peak of the outbreak, 30-40 children needed daily monitoring. Because of the protocols we had developed based on our ongoing STEC research, we were able to rapidly implement them to prevent severe illness,” says Dr. Mohamed Eltorki , MD, PGME'15, emergency department physician and first author on the study. “When a blood test detected early changes and warning signs of HUS, we admitted the child to hospital before they became critically ill.”
Published in JAMA Network Open , the authors reported that, overall, 40 children were hospitalized, 21 developed HUS and nine required dialysis. The number of children who developed HUS was less than half of what would typically occur in an outbreak of this size.
“Historically, with STEC infections, we gave families a list of things to monitor for and told them to come back to the ED (emergency department) if any of the symptoms worsened,” says Freedman. “However, we’ve learned that these symptoms and signs do not become apparent until HUS fully develops. Performing daily laboratory monitoring ensured that all kids with evolving disease were identified before complications occurred.”
The researchers add the response required a co-ordinated effort by several Calgary hospitals.
“I know many families who are very grateful for the care their children received. Without the STEC expertise that exists here in Calgary I believe the outcomes would have been different for a lot of kids,” says Hull.
Hull has become a patient-partner to promote awareness of STEC and advocate for system improvements. Hank has fully recovered; however, his younger sister continues to deal with health complications from STEC infection.
“Because of the ongoing research, we were in a position to provide world-class care. And it made a difference,” says Freedman.
The study was supported by Freedman’s Alberta Children’s Hospital Foundation ’s Professorship in Child Health and Wellness.
JAMA Network Open
10.1001/jamanetworkopen.2026.1278
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Shiga Toxin–Producing Escherichia coli Outbreak in Canadian Daycare Centers
10-Mar-2026
Dr P. I. Tarr reported receiving grants from National Institute of Allergy and Infectious Diseases (NIAID), personal fees from UpToDate, and serving as an unpaid member of a data safety monitoring board for Inmunova during the conduct of the study. Dr Pavia reported receiving personal fees from Haleon and GSK, and Sanford Guide to Antimicrobial Therapy for serving as associate editor outside the submitted work. Dr Freedman reported receiving personal fees from UpToDate outside the submitted work. No other disclosures were reported.