Viral hepatitis is a systemic disease primarily involving the liver. Most cases of acute viral hepatitis in children and adults are caused by one of the following five agents: hepatitis A virus (HAV), the etiologic agent of viral hepatitis type A (infectious hepatitis); hepatitis B virus (HBV), which is associated with viral hepatitis B (serum hepatitis); hepatitis C virus (HCV), the agent of hepatitis C (common cause of posttransfusion hepatitis); hepatitis D (HDV), a defective virus dependent on coinfection with HBV; or hepatitis E virus (HEV), the agent of enterically transmitted hepatitis. Additional well-characterized viruses that can cause sporadic hepatitis, such as yellow fever virus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, rubella virus, and the enteroviruses, are discussed in other chapters. Hepatitis viruses produce acute inflammation of the liver, resulting in a clinical illness characterized by fever, gastrointestinal symptoms such as nausea and vomiting, and jaundice. Regardless of the virus type, identical histopathologic lesions are observed in the liver during acute disease.
PROPERTIES OF HEPATITIS VIRUSES
The characteristics of the five known hepatitis viruses are shown in Table 35-1. Nomenclature of the hepatitis viruses, antigens, and antibodies is presented in Table 35-2.
TABLE 35-1Characteristics of Hepatitis Viruses |Favorite Table|Download (.pdf) TABLE 35-1 Characteristics of Hepatitis Viruses
|Virus ||Hepatitis A ||Hepatitis B ||Hepatitis C ||Hepatitis D ||Hepatitis E |
|Family ||Picornaviridae ||Hepadnaviridae ||Flaviviridae ||Unclassified ||Hepeviridae |
|Genus ||Hepatovirus ||Orthohepadnavirus ||Hepacivirus ||Deltavirus ||Hepevirus |
|Virion ||27 nm, icosahedral ||42 nm, spherical ||60 nm, spherical ||35 nm, spherical ||30–32 nm, icosahedral |
|Envelope ||No ||Yes (HBsAg) ||Yes ||Yes (HBsAg) ||No |
|Genome ||ssRNA ||dsDNA ||ssRNA ||ssRNA ||ssRNA |
|Genome size (kb) ||7.5 ||3.2 ||9.4 ||1.7 ||7.2 |
|Stability ||Heat and acid stable ||Acid sensitive ||Ether sensitive, acid sensitive ||Acid sensitive ||Heat stable |
|Transmission ||Fecal–oral ||Parenteral ||Parenteral ||Parenteral ||Fecal–oral |
|Prevalence ||High ||High ||Moderate ||Low, regional ||Regional |
|Fulminant disease ||Rare ||Rare ||Rare ||Frequent ||In pregnancy |
|Chronic disease ||Never ||Often ||Often ||Often ||Never |
|Oncogenic ||No ||Yes ||Yes ||Unknown ||No |
TABLE 35-2Nomenclature and Definitions of Hepatitis Viruses, Antigens, and Antibodies |Favorite Table|Download (.pdf) TABLE 35-2 Nomenclature and Definitions of Hepatitis Viruses, Antigens, and Antibodies
|Disease ||Component of System ||Definition |
|Hepatitis A ||HAV ||Hepatitis A virus. Etiologic agent of infectious hepatitis. A picornavirus, the prototype of genus Hepatovirus |
| ||Anti-HAV ||Antibody to HAV. Detectable at onset of symptoms; lifetime persistence |
| ||IgM anti-HAV ||IgM class antibody to HAV. Indicates recent infection with hepatitis A; positive result up to 4–6 months after infection |
|Hepatitis B ||HBV ||Hepatitis B virus. Etiologic agent of serum hepatitis. A hepadnavirus |
| ||HBsAg ||Hepatitis B surface antigen. Surface antigen(s) of HBV detectable in large quantity in serum; several subtypes identified |
| ||HBeAg ||Hepatitis B e antigen. Associated with HBV nucleocapsid; indicates viral replication; circulates as soluble antigen in serum |
| ||HBcAg ||Hepatitis B core ...|
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.