GPT and hepatitis A virus infection: In 2018, a confirmed case of acute HAV infection was defined as illness occurring in a person with 1) a discrete onset of hepatitis symptoms, 2) jaundice or elevated alanine aminotransferase (ALT) or aspartate aminotransferase (AST), and 3) reactive anti-HAV immunoglobulin (Ig) M antibody (3).