ABSTRACT
Viral hepatitis, or inflammation of the liver due to a viral infection, was initially considered as one disease. Transmission studies done during the mid-twentieth century indicated the existence of at least two distinct transmissible agents as being responsible for this condition, and these were provisionally named hepatitis A (fecal-oral transmission and short incubation period) and hepatitis B (parenteral transmission and long incubation period). 1 The agent for the former was first identified in 1970s in stool specimens from affected human volunteers using immune electron microscopy. 2 It was then named hepatitis A virus (HAV)—using the first letter of the English language—in keeping with the provisional nomenclature, even though the agent for parenteral hepatitis (the “hepatitis B virus”) had been discovered before it. Since then, additional distinct hepatotropic viruses with predominant parenteral (hepatitis C virus and hepatitis D virus) or oral (hepatitis E virus) spread have been discovered.
