Acute Hepatitis of Unknown Origin in Children: Two Cases in a Portuguese Hospital.

Several cases of paediatric acute hepatitis of an unknown aetiology have been described in these last few months and in several countries worldwide. We present two patients, a 7-month-old girl and an 8-year-old boy, with gastrointestinal symptoms and lethargy, associated with elevation of transaminase levels. Serologies for hepatitis A-E virus and PCR test to SARS-CoV-2 were all negative. In the first case, an adenovirus serotype C could be isolated in a respiratory sample as well as cytomegalovirus (CMV) in the blood (100 copies/mL). In both children, there was a progressive decrease in the hepatic markers and symptomatic resolution, compatible with a good prognosis, also seen globally in most cases. To date, infection remains the most plausible cause to consider, especially when it is presumed to be linked to adenovirus. Other potential agents and causes are still being evaluated, thus emphasizing the importance of continuous epidemiological surveillance, notification, and detailed study of all hepatitis cases.