At least 169 cases of acute hepatitis among children aged 1 month to 16 years old have been identified in 12 countries, the World Health Organization reported April 23.
Seventeen children required liver transplantation. At least one death has been reported.
Most of the cases have been identified in the United Kingdom (114). Other countries identifying cases are Spain (13), Israel (12), the United States (9) Denmark (6), Ireland (<5), The Netherlands (4), Italy (4), Norway (2), France (2), Romania (1) and Belgium (1).
Many cases reported gastrointestinal symptoms including abdominal pain, diarrhea and vomiting preceding presentation with severe acute hepatitis, and increased levels of liver enzymes or alanine aminotransaminase and jaundice. Most cases did not have a fever. The common viruses that cause acute viral hepatitis (viruses A, B, C, D and E) have not been detected in any of these cases, according to the WHO.
The WHO said determining the cause of these acute hepatitis cases is the priority to further refine control and prevention actions. Adenovirus has been detected in at least 74 of the 169 cases.
"While adenovirus is currently one hypothesis as the underlying cause, it does not fully explain the severity of the clinical picture," the organization said. "Factors such as increased susceptibility amongst young children following a lower level of circulation of adenovirus during the COVID-19 pandemic, the potential emergence of a novel adenovirus, as well as SARS-CoV-2 co-infection, need to be further investigated."
The WHO's update follows a health advisory issued by the CDC April 21 to alert healthcare providers who may encounter pediatric patients with hepatitis of unknown etiology to consider adenovirus testing and to elicit reporting of such cases to state public health authorities and the CDC.