Update: Hepatitis of unknown origin in children
Following the reports of cases of acute hepatitis of unknown origin by the UK Health Security Agency, additional cases in children have been reported in Denmark, Ireland, the Netherlands, and Spain.
In addition, nine cases of acute hepatitis among children between 1 and 6 years old in the state of Alabama in the United States who also tested positive for adenovirus have been reported.
Investigations are ongoing in all countries reporting cases. At present, the exact cause of hepatitis in these children remains unknown. The incident team in the United Kingdom, where most of the cases have occurred to date, consider that an infective cause is most likely based on the clinical and epidemiological features of the cases under investigation.
ECDC is working with teams in each of the countries reporting cases, along with WHO and other key partners to support the ongoing investigations. ECDC facilitates the sharing of information as it becomes available, as well as tools for investigations.
Over the past weekend, the agency continued sharing all available information with countries through its Hepatitis Network and with the clinical organisations the European Association for the Study of the Liver and the European Society of Clinical Microbiology and Infectious Diseases ESCMID.
ECDC will continue to monitor this event through its epidemic intelligence activities and liaise with Member States and international partners.
Epidemiological summary
On 5 April 2022, the United Kingdom reported an increase in acute hepatitis cases of unknown aetiology among previously healthy children aged under 10 years from Scotland.
On 12 April, the United Kingdom reported that in addition to the cases in Scotland there were approximately 61 further cases under investigation in England, Wales and Northern Ireland, with most of these cases aged between 2 and 5 years.
On 14 April, Scotland reported that of the 13 cases under investigation two pairs of cases were epidemiologically linked.
The cases in the United Kingdom presented clinically with severe acute hepatitis, with increased levels of liver enzymes (aspartate transaminase (AST) or Alanine aminotransaminase (ALT) greater than 500 IU/L) and many cases were jaundiced. Some of the cases reported gastrointestinal symptoms, including abdominal pain, diarrhoea and vomiting in the preceding weeks.
Most cases did not have a fever. Some of the cases required care at specialist children’s liver units and a few had undergone liver transplantation.
Initial hypotheses by the incident team in the United Kingdom around the aetiological origin of the cases centred around an infectious agent or a possible toxic exposure. No link to the COVID-19 vaccine was identified and detailed information collected through a questionnaire to cases about food, drink and personal habits failed to identify any common exposure.
Toxicological investigations are ongoing but an infectious aetiology is considered more likely given the epidemiological picture and the clinical features of the cases.
Laboratory investigations of the cases excluded viral hepatitis types A, B, C, D and E in all cases. Of the 13 cases reported by Scotland for which detailed information is available regarding testing, three tested positive for SARS-CoV-2 infection, five tested negative and two were documented to have had an infection in the three months before presentation. Eleven of these 13 cases had results for adenovirus testing and five tested positive.
