On April 5, 2022, WHO was notified of 10 cases of severe acute hepatitis of unknown etiology in children under the age of 10 years, across central Scotland.
By April 8, 74 cases had been identified in the United Kingdom. Hepatitis viruses (A, B, C, E, and D where applicable) have been excluded after laboratory testing while further investigations are ongoing to understand the etiology of these cases. Given the increase in cases reported over the past one month and enhanced case search activities, more cases are likely to be reported in the coming days.
On April 5, 2022, the International Health Regulations (IHR) National Focal Point (NFP) for the United Kingdom notified WHO of 10 cases of severe acute hepatitis of unknown etiology in previously healthy young children (age range: 11 months to five-year-old) across central Scotland. Of these 10 cases, 9 had onset of symptoms in March 2022 while one case had an onset of symptoms in January 2022. Symptoms included jaundice, diarrhea, vomiting and abdominal pain. All 10 cases were detected when hospitalized.
As of April 8, 2022, further investigations across the United Kingdom have identified a total of 74 cases (including the 10 cases) fulfilling the case definition. The clinical syndrome in identified cases is of acute hepatitis with markedly elevated liver enzymes, often with jaundice, sometimes preceded by gastrointestinal symptoms, in children principally up to 10 years old. Some cases have required transfer to specialist children’s liver units and six children have undergone liver transplantation. As of 11 April, no death has been reported among these cases and one epidemiologically linked case has been detected.
Laboratory testing has excluded hepatitis type A, B, C, and E viruses (and D where applicable) in these cases while Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and/or adenovirus have been detected in several cases. The United Kingdom has recently observed an increase in adenovirus activity, which is co-circulating with SARS-CoV-2, though the role of these viruses in the pathogenesis (mechanism by which disease develops) is not yet clear. No other epidemiological risk factors have been identified to date, including recent international travel. Overall, the etiology of the current hepatitis cases is still considered unknown and remains under active investigation. Laboratory testing for additional infections, chemicals and toxins is underway for the identified cases.
Following the notification from the UK, less than five cases (confirmed or possible) have been reported in Ireland, further investigations into these are ongoing. Additionally, three confirmed cases of acute hepatitis of unknown etiology have been reported in children (age range 22-month-old to 13-year-old) in Spain. The national authorities are currently investigating these cases.
Further investigations by the national authorities are ongoing to include more detailed exposure history, toxicology testing, and additional virological/microbiological tests. Guidance has been issued to experts to support a thorough investigation of suspected cases.
Further investigations and a clinical and public health response to the cases reported are also being undertaken in Ireland and Spain.