05/19/22 Health Advisory: Severe Hepatitis of Unknown Cause in Children

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Actions Requested

  • Be aware of severe cases of hepatitis in children that are occurring in the U.S. and worldwide.
  • Consider adenovirus testing in pediatric patients with hepatitis of unknown cause (see preferred samples below).
  • Report suspect cases in children to Whatcom County Health Department. A suspect case is a child with elevated AST or ALT (>500 U/L) who have an unknow etiology for their hepatitis, with or without any adenovirus testing) since Oct. 1, 2021.


As of May 18, 2022, CDC and health departments are investigating 180 children with hepatitis of unknown origin across 26 states and territories, including Washington. A possible association between pediatric hepatitis and adenovirus infection is currently under investigation after laboratory testing identified adenovirus type 41 in several cases. Because this investigation is ongoing and includes reviewing cases of hepatitis of unknown cause with onset since October 2021, patients under investigation are not limited to current or newly diagnosed pediatric hepatitis illnesses.

Clinicians should consider collecting the following specimen types if available from pediatric patients with hepatitis of unknown cause for adenovirus detection:

  • Blood specimen collected in EDTA (whole blood, plasma, or serum); whole blood is preferred to plasma and serum). Quest and ARUP can provide whole blood PCR testing.
  • Respiratory specimen (nasopharyngeal swab, sputum, or bronchioalveolar lavage).
  • Stool specimen or rectal swab; a stool specimen is preferred to a rectal swab.
  • Liver tissue, if a biopsy was clinically indicated, or if tissue from native liver explant or autopsy is available.
    • Formalin-fixed, paraffin embedded liver tissue
    • Fresh liver tissue, frozen on dry ice or liquid nitrogen immediately or as soon as possible, and stored at ≤ -70°C

Nucleic acid amplification testing (NAAT), such as polymerase chain reaction (PCR), is preferred for adenovirus detection (currently not available for FFPE liver biopsy or native liver explant).


CDC Health Update:  https://emergency.cdc.gov/han/2022/han00465.asp

Contacting the Health Department

360-778-6100     Main Call Line – available M-F 8:30am to 4:30pm

360-715-2588     Afterhours Answering Service – available after 4:30pm and weekends

360-778-6150     Communicable Disease Report Line – 24 hours a day 7 days a week

360-778-6103     Confidential Communicable Disease Fax – 24 hours a day 7 days a week

1500 N State Street, Bellingham WA 98225