The significant hepatitis viruses include types A, B, C, D, and E. The transmission of B, C, and D is parenteral, close contact (e.g., sexually transmitted), or perinatal (congenital). Type A is spread by fecal/oral contamination and E is waterborne. The incubation periods are weeks long, somewhat shorter for A and E than the others.
Hepatitis A virus (HAV) infection is generally subclinical or a mild acute and self-limited infection, with clearance of the virus. A small number of HAV infections (<1%) lead to fulminant hepatitis.
Hepatitis B virus (HBV) infections are usually cleared by the host after acute infection, but in up to 20% of cases there is persistence of the virus. Most carriers of hepatitis B remain healthy, but up to 5% can develop ongoing hepatitis after 6 months, most often a chronic persistent hepatitis that eventually resolves, while in fewer cases chronic active hepatitis develops that can proceed to cirrhosis. The risk for hepatocellular carcinoma is increased when there is chronic hepatitis and cirrhosis.
Hepatitis C virus (HCV) produces a carrier state in over 80% of cases and some go on to chronic hepatitis. The risk for hepatocellular carcinoma is increased when there is chronic hepatitis and cirrhosis