Diarrhea may be present in young children, whereas constipation is more common in adults. Jaundice and dark urine develop several days to a week after onset of systemic symptoms. Anicteric infections are common in young children. A patient who appears severely ill is likely to have another cause of hepatitis or an atypical course. Mild hepatomegaly and right upper quadrant tenderness may be present.
Transmission is via the fecal-oral route, and viral replication occurs in the liver.
HAV is then excreted into the bile and can be found in highest concentrations in the stool, especially during the 2-week period prior to onset of jaundice. This correlates with the period of peak infectivity. Common-source outbreaks from contaminated food or water may occur. Childcare centers may be a source of outbreaks. These outbreaks may not be identified until an adult contact has recognizable HAV infection, because young children are often asymptomatic or have anicteric illness.