Acute, Severe Hepatitis of Unknown Origin in Children

On April 15, 2022 the World Health Organization issued an alert highlighting cases of acute, severe hepatitis of unknown origin identified in young children in the United Kingdom. Since then, additional cases have been reported in other countries. Cases have been reported in children from 1 month to 16 years of age.

It remains to be seen whether this number represents an increase in cases of unknown origin compared to similar time periods in previous years or if any of these cases will be confirmed to be caused by a novel clinical entity.

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 these cases, the common causes have been ruled out. Hepatitis A, B, C, D, or E viruses were not identified in the reported cases. Investigations are ongoing into the cause of these cases of severe, acute inflammation of the liver.

Public Health Response

The Public Health Agency of Canada (PHAC) is monitoring for potential risks to Canadians and is working with provincial and territorial partners to investigate potential cases. Manitoba Health is working closely with PHAC to increase surveillance for cases of acute, severe hepatitis of unknown origin to better understand its cause and potential impact. Manitoba Health is aware of and is investigating potential cases in the province.

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.

Health care providers are being requested to report any potential cases to public health.

PHAC Working Case Definition (May 13, 2022):

  • Confirmed: N/A at present
  • Probable: 
    • A person who is 16 years and younger presenting with severe acute hepatitis since 1 October 2021 and requiring hospitalization, AND
    • With elevated serum transaminase >500 IU/L (AST or ALT), AND
    • Excluding hepatitis caused or attributed to a hepatitis virus (A, B, C, D, E1) or a known or expected presentation of a drug or medication; a genetic, congenital, or metabolic condition; an oncologic, vascular, or ischemia related condition; or an acute worsening of chronic hepatitis.

1 If hepatitis D or E serology results are pending or test was not done, but other criteria met, these can be reported as probable cases.

Resources for Health Care Providers:
For More Information:

Communicable Disease Control (CDC)
Public Health
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