Reviewed by Rishi Desai, MD, MPH
Hepatitis A virus
Hepatitis A infection is caused by the hepatitis A virus. Humans are the only known reservoir. It is usually a self-limited illness that does not become chronic. Fulminant hepatic failure occurs in less than one percent of cases. Infection confers lifelong immunity and is preventable via vaccination.
The clinical spectrum of hepatitis B is wide. The acute phase manifestations range from subclinical or anicteric to icteric hepatitis and, in some cases, fulminant hepatitis. The chronic phase manifestations range from asymptomatic carrier state to chronic hepatitis, cirrhosis, and hepatocellular carcinoma.
The vast majority of patients with hepatitis C virus infection are minimally symptomatic, although fatigue is a common complaint. Even if cirrhosis develops, many patients have only nonspecific symptoms. Some patients have extrahepatic findings that are directly related to hepatitis C virus infection.
Hepatitis D virus
The hepatitis D virus is a defective pathogen that requires the presence of the hepatitis B virus for infection. The hepatitis D virion is composed of an outer lipoprotein envelope made of the surface antigen of the hepatitis B virus and an inner ribonucleoprotein structure in which the hepatitis D virus genome resides.
Viral hepatitis is liver inflammation due to a viral infection. It may present in acute (recent infection, relatively rapid onset) or chronic forms. The most common causes of viral hepatitis are the five unrelated hepatotropic viruses Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, and Hepatitis E. In addition to the nominal hepatitis viruses, other viruses that can also cause liver inflammation include Herpes simplex, Cytomegalovirus, Epstein–Barr virus, and Yellow fever.
Hepatitis E virus is one of the most common causes of acute viral hepatitis. Although it has a global distribution, a large majority of its disease burden is in Asia and Africa. Hepatitis E virus is a positive-sense single-stranded non-enveloped RNA icosahedral virus, and has a fecal-oral transmission route.