Table 1.

Working case definition of acute non HepA-E hepatitis.

Source	Case Definition
WHO/ECDC
Confirmed acute non HepA-E hepatitis	Not applicable
Probable acute non HepA-E hepatitis	The presence of acute hepatitis with elevated level(s) of ALT or AST higher than 500 IU/L, and negativity for viral hepatitis (A–E) in children aged 16 years or younger, since 1 October 2021
Epi-linked acute non HepA-E hepatitis	The presence of acute hepatitis in a person who has been in close contact with a probable case of acute non HepA-E hepatitis, since 1 October 2021
UK Health Security Agency
Confirmed acute non HepA-E hepatitis	The presence of acute hepatitis with elevated level(s) of ALT or AST higher than 500 IU/L, and negativity for viral hepatitis (A–E) in children aged 10 years or less any time from 1 January 2022
Possible acute non HepA-E hepatitis	The presence of acute hepatitis with elevated level(s) of ALT or AST higher than 500 IU/L, and negativity for viral hepatitis (A-E) in those aged between 11 and 16 years any time from 1 January 2022
Epi-linked acute non HepA-E hepatitis	The presence of acute hepatitis in a person who has been in close contact with a probable case of acute non HepA-E hepatitis, any time from 1 January 2022

Abbreviations: WHO: World Health Organization; ECDC: The European Centre for Disease Prevention and Control; UK: United Kingdom; ALT: alanine aminotransferase; AST: aspartate aminotransferase; IU: international unit.