Acute, Severe Hepatitis of Unknown Origin in Children

Updated: October 20, 2022

In response to the alert issued on April 15, 2022 by the World Health Organization (WHO) highlighting cases of acute, severe hepatitis of unknown origin identified in young children in the United Kingdom, the Public Health Agency of Canada (PHAC) initiated an investigation to determine whether there was an increase in cases of acute, severe hepatitis of unknown origin compared to similar time periods in previous years in Canada, or if a cause or factors contributing to the illness could be identified. Detailed epidemiological, clinical, and laboratory investigations were performed for reported cases. Globally, cases are investigated and reported to the WHO.

As of September 23, 2022, the investigation by PHAC was closed. Some countries continue to investigate cases, and PHAC continues to monitor the outcomes as reported to the WHO.

Symptoms of acute hepatitis

Symptoms of acute hepatitis include jaundice (the skin and/or the whites of the eyes turn yellow), nausea, vomiting, diarrhea and abdominal pain. Fever can be a symptom of acute hepatitis, but has been rare in the cases reported and under investigation.


There are many causes for hepatitis in children. In the cases under investigation, the common causes, including Hepatitis A, B, C, D, or E viruses, have been ruled out. At this time, the cause of the reported illnesses is still unknown. It is not unusual for the cause of some hepatitis cases in children to remain unknown.

Public Health Response

Between April and September 2022, the Public Health Agency of Canada (PHAC) collaborated with provincial and territorial health partners to investigate 28 cases in Canada. It was determined from the investigation that the number of cases reported during the course of the investigation was not above baseline numbers previously seen in Canada. Accordingly, as of September 23, 2022 the PHAC has closed its investigation into cases of severe acute hepatitis of unknown origin in Canada. However, PHAC continues to monitor the outcomes of the investigations as reported to the WHO. Parents and caregivers should be aware of the symptoms of acute hepatitis and follow up with their healthcare provider with any concerns. Children with jaundice (the skin and/or the whites of the eyes turn yellow) should be assessed by their health care provider. Gastrointestinal symptoms are commonly seen in children, but severe hepatitis in children remains a rare occurrence.

As of October 20, 2022 health care providers are no longer required to report any potential cases to public health.

Resources for Health Care Providers:
For More Information:

Communicable Disease Control (CDC)
Public Health
Manitoba Health

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