On 5 April 2022, the United Kingdom reported an increase of cases of severe acute hepatitis of unknown aetiology in children, several needing hospitalisation and some required liver transplant or died. Thereafter, 35 countries reported probable cases, almost half of them in Europe. Facing the alert, on 28 April, Portugal created a multidisciplinary Task Force (TF) for rapid detection of probable cases and response. The experts of the TF came from various disciplines: clinicians, laboratory experts, epidemiologists, public health experts and national and international communication. Moreover, Portugal adopted the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) case definition and recommendations. By 31 December 2022, 28 probable cases of severe acute hepatitis of unknown aetiology were reported: 16 male and 17 aged under 2 years. Of these cases, 23 were hospitalised but none required liver transplant or died. Adenovirus was detected from nine of 26 tested cases. No association was observed between adenovirus infection and hospital admission after adjusting for age, sex and region in a binomial regression model. The TF in Portugal may have contributed to increase awareness among clinicians, enabling early detection and prompt management of the outbreak.
Keywords: Europe; acute hepatitis unknown origin; adenovirus; cross-border threat; hospitalisation; liver transplant; outbreak response; paediatrics.