e-Medical Note:

Acute Viral Hepatitis

Acute viral hepatitis is a systemic infection affecting the liver predominantly. 

Almost all cases of acute viral hepatitis are caused by one of five viral agents: 

• Hepatitis A virus (HAV) 

• hepatitis B virus (HBV)

• Hepatitis C virus (HCV)

• HBV-associated delta agent or hepatitis D virus (HDV)

• Hepatitis E virus (HEV). 

Other transfusion-transmitted agents, e.g., "hepatitis G" virus and "TT" virus, have been identified but do not cause hepatitis. 

All these human hepatitis viruses are RNA viruses except for hepatitis B, which is a DNA virus. 

Although these agents can be distinguished by their molecular and antigenic properties, all types of viral hepatitis produce clinically similar illnesses - These range from asymptomatic and inapparent to fulminant and fatal acute infections common to all types, on the one hand, and from subclinical persistent infections to rapidly progressive chronic liver disease with cirrhosis and even hepatocellular carcinoma, common to the bloodborne types (HBV, HCV and HDV), on the other.

Chronic Viral Hepatitis

• Both the enterically transmitted forms of viral hepatitis, hepatitis A and E, are self-limited and do not cause chronic hepatitis, EXCEPT for rare reports in which acute hepatitis A serves as a trigger for the onset of autoimmune hepatitis in genetically susceptible patients. 

• In contrast, the entire clinicopathologic spectrum of chronic hepatitis occurs in patients with chronic viral hepatitis B and C as well as in patients with chronic hepatitis D superimposed on chronic hepatitis B.