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

Three kids with backpacks walking away

Requested actions

  • Be aware cases of severe hepatitis are occurring in children in the United States and worldwide.
  • Consider adenovirus testing for pediatric patients with hepatitis of unknown cause.
  • Report suspected cases to the Health Department by calling (360) 414-5599 x 6431.
    • A suspected case is a child with elevated AST or ALT (>500 U/L) with hepatitis of unknow etiology—with or without adenovirus testing, regardless of results—since Oct. 1, 2021.


Centers for Disease Control and Prevention (CDC) is investigating 180 cases of children with hepatitis of unknown cause across 26 states and territories, including Washington. CDC is investigating a possible link to adenovirus infection, as lab tests found adenovirus type 41 in several cases. Investigators are reviewing cases with onset as early as October 2021.

Consider collecting (for adenovirus detection) the following from pediatric patients with hepatitis of unknown cause:

  • Blood specimen collected in EDTA—whole blood is best, but plasma or serum are acceptable.
  • Respiratory specimen—nasopharyngeal swab, sputum or bronchioalveolar lavage.
  • Stool specimen or rectal swab—stool specimen is best but rectal swab is acceptable.
  • Liver tissue—from clinically indicated biopsy, native liver explant or autopsy.
    • Formalin-fixed, paraffin embedded liver tissue.
    • Fresh liver tissue, frozen on dry ice or liquid nitrogen as soon as possible, and stored at ≤ -70°C.

Report suspected cases to the Health Department by calling the reporting line: (360) 414-5599 x 6431 during business hours, (360) 636-9595 after hours or use the reporting form.

View CDC’s health advisory.


Contact Cowlitz County Health & Human Services at (360) 414-5599.