[The relationship between adenovirus infection and severe acute hepatitis of unknown etiology]

Adenovirus infection can occur in all regions or countries of the world, with no obvious seasonality, but pandemics mostly occur in winter or early spring. Adenovirus infection is self-limited among immunocompetent host with supportive care, however fatal infection can occur among immunocompromised patients, mainly affecting respiratory, gastrointestinal tract and adjunctiva and very rarely causing hepatitis, cholecystitis, pancreatitis, hemorrhagic cystitis, myocarditis, meningitis or encephalitis. Adenovirus hepatitis mainly occur in malignant tumors or organ transplantation patients, but acute severe hepatitis can occur even in immunocompetent children or adults. On 5 April 2022, WHO was notified of 10 cases of severe acute hepatitis of unknown etiology in children. As of 21 April 2022, at least 169 cases of acute hepatitis of unknown origin have been reported from 12 countries (including 11 WHO European Region countries and the United States). Adenovirus has been detected in at least 74 cases; SARS-CoV-2 was identified in 20 cases of those that were tested. Furthermore, 19 were detected with a SARS-CoV-2 and adenovirus co-infection. At present, the etiology has not been fully elucidated. The leading hypotheses center around adenovirus, and the relationship with SARS-CoV-2 needs to be further ruled out.