Hepatitis A infection occurs almost exclusively from ingestion (fecal-oral transmission) of contaminated food or water. The injury to liver cells is secondary to the hosts immunologic response and the severity of symptoms following infection directly correlate with patient age.
The liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are raised and levels may exceed values of 10,000 mIU/ml, with ALT levels generally greater than AST levels. Levels usually return to baseline over 5-20 weeks. The enzyme alkaline phosphatase rises in the obstructive (cholestatic) phase of the disease following the rises in transaminase levels. Bilirubin level follows rises in ALT and AST levels. Levels may be quite high and can remain elevated for several months; persistence beyond 3 months indicates cholestatic infection with older patients having higher bilirubin levels.
Treatment is generally supportive, with no specific therapy. Bed rest is often advised and a normal diet should be taken, as there is no specific dietary restriction. Prolonged cholestasis may follow the acute infection and is characterized by a protracted period of jaundice (>3 months) and resolves without intervention. Corticosteroids and ursodeoxycholic acid may shorten the period of cholestasis. The usual features of cholestatic viral hepatitis A are pruritus (itching), fever, diarrhea, and weight loss, with serum bilirubin levels greater than 10 mg/dl.