Adeno-Associated Virus 2 and Human Adenovirus F41 in Wastewater during Outbreak of Severe Acute Hepatitis in Children, Ireland

During April-July 2022, outbreaks of severe acute hepatitis of unknown etiology (SAHUE) were reported in 35 coun-tries. Five percent of cases required liver transplantation, and 22 patients died. Viral metagenomic studies of clinical samples from SAHUE cases showed a correlation with hu-man adenovirus F type 41 (HAdV-F41) and adeno-associat-ed virus type 2 (AAV2). To explore the association between those DNA viruses and SAHUE in children in Ireland, we quantified HAdV-F41 and AAV2 in samples collected from a wastewater treatment plant serving 40% of Ireland's popu-lation. We noted a high correlation between HAdV-F41 and AAV2 circulation in the community and SAHUE clinical cas-es. Next-generation sequencing of the adenovirus hexon in wastewater demonstrated HAdV-F41 was the predominant HAdV type circulating. Our environmental analysis showed increased HAdV-F41 and AAV2 prevalence in the commu-nity during the SAHUE outbreak. Our findings highlight how wastewater sampling could aid in surveillance for respira-tory adenovirus species.