Excerpt from Hepatitis, Viral


Synonyms, Key Words, and Related Terms: acute hepatitis, chronic hepatitis, hepatitis A, hepatitis A virus, HAV, hepatitis B, hepatitis B virus, HBV, hepatitis C, hepatitis C virus, HCV, hepatitis D, hepatitis D virus, HDV, delta hepatitis, delta virus, hepatitis E, hepatitis E virus, HEV, non-A non-B hepatitis, NANB hepatitis, NANB, non-A/non-E hepatitis, NANE, viral infection, fulminant hepatic failure, FHF, hepatocellular carcinoma, HCC, liver cancer, liver failure, viral hepatitis, acute viral hepatitis, chronic viral hepatitis, hepatitis virus infection, hepatitis viral infection, infectious hepatitis, serum hepatitis

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Definition

The term hepatitis describes inflammation of the liver. Hepatitis may be caused by alcohol, drugs, autoimmune diseases, metabolic diseases, and viruses. Viral infection accounts for more than half the cases of acute hepatitis in the United States.

The term viral hepatitis is often thought to be synonymous with diseases caused by the known hepatotropic viruses, including hepatitis viruses A, B, C, D, and E. However, the term hepatotropic is itself a misnomer. Infections with hepatitis viruses, especially hepatitis viruses B and C, have been associated with a wide variety of extrahepatic manifestations. Infrequent causes of viral hepatitis include adenovirus, cytomegalovirus, Epstein-Barr virus, and, rarely, herpes simplex virus infection. Newly discovered pathogens (eg, virus SEN-V) may account for additional cases of non-A/non-E hepatitis.

For excellent patient education resources, visit eMedicine's Hepatitis Center; Liver, Gallbladder, and Pancreas Center; and Public Health Center. Also, see eMedicine's patient education articles Hepatitis A; Hepatitis B; Hepatitis C; Cirrhosis; Immunization Schedule, Children; and Immunization Schedule, Adults.

Epidemiology of viral hepatitis

Hepatitis A virus (HAV); hepatitis B virus (HBV); hepatitis C virus (HCV); hepatitis D virus (HDV), which requires coexisting HBV infection; and hepatitis E virus (HEV) cause 95% of cases of acute viral hepatitis observed in the United States. Whether hepatitis G virus (HGV) is pathogenic in humans remains unclear. HAV is the most common cause of acute hepatitis in the United States; HCV is the most common cause of chronic hepatitis. Typical patterns of virus transmission are as follows, with + symbols indicating the frequency of transmission (more + symbols indicated increased frequency):

  • Fecal-oral transmission

    • HAV (+++)

    • HEV (+++)

  • Parenteral transmission

    • HBV (+++)

    • HCV (+++)

    • HDV (++)

    • HGV (++)

    • HAV (+)

  • Sexual transmission

    • HBV (+++)

    • HDV (++)

    • HCV (+)

  • Perinatal transmission

    • HBV (+++)

    • HCV (+)

    • HDV (+)

  • Sporadic (unknown) transmission

    • HBV (+)

    • HCV (+)

Natural history of acute viral hepatitis

The term viral hepatitis can describe either a clinical illness or the histological findings associated with the disease. Acute infection with a hepatitis virus may result in conditions ranging from subclinical disease to self-limited symptomatic disease to fulminant hepatic failure. Adults with acute hepatitis A or B are usually symptomatic. Persons with acute hepatitis C may be either symptomatic or asymptomatic (ie, subclinical).

Typical symptoms of acute hepatitis are fatigue, anorexia, nausea, and vomiting. Very high aminotransferase values (>1000 U/L) and hyperbilirubinemia are often observed. Severe cases of acute hepatitis may progress rapidly to acute liver failure, marked by poor hepatic synthetic function. This is often defined as a prothrombin time of 16 seconds or an international normalized ratio of 1.5 in the absence of prior liver disease.

Fulminant hepati .....

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