This document discusses hepatitis A virus (HAV) which causes hepatitis A, an infectious liver disease. HAV is a picornavirus with a single serotype that is transmitted primarily through the fecal-oral route. It does not cause chronic infection like hepatitis B or C. While many cases are asymptomatic, symptomatic cases typically have an incubation period of 2-6 weeks followed by jaundice, abdominal pain, and fever. HAV infection is diagnosed through detection of IgM antibodies and past infection through IgG antibodies.