Viral hepatitis has appeared as a foremost public health trouble throughout the world distressing hundreds of millions of people. Viral hepatitis is a reason of substantial morbidity and transience in the human population, both from keen infection and chronic sequelae which include, in the case of hepatitis B, C and D, chronic active hepatitis and cirrhosis. Hepatocellular carcinoma which is one of the ten the majority familiar cancers worldwide, is intimately linked with hepatitis B, and at least in some regions of the world with hepatitis C virus.
The hepatitis viruses include a variety of unrelated and habitually highly unusual human pathogens.
Hepatitis A virus
Hepatitis A virus (HAV), classify as hepatovirus, is a little, undeveloped symmetrical RNA virus which shares many of the characteristics of the picornavirus family, and is the reason of infectious or epidemic hepatitis transmitted by the fecal-oral route.
Hepatitis B virus
Hepatitis B virus (HBV), a member of the hepadnavirus group, double-stranded DNA viruses which replicate, unusually, by reverse transcription. Hepatitis B virus is widespread in the human population and hyperendemic in many parts of the world. A number of variants of this virus have been described. Natural hepadna virus infections also happen in other mammals including woodchucks, beechy ground squirrels and ducks.
Hepatitis C virus
Hepatitis C virus (HCV), is an enveloped single-stranded RNA virus which appears to be vaguely related (possibly in its evolution) to flaviviruses, though hepatitis C is not transmitted by arthropod vectors. Numerous genotypes have been identified. Infection with this more recently identified virus is common in many countries. Hepatitis C virus is associated with chronic liver disease and also with major liver cancer in some countries.
Hepatitis D virus
Hepatitis D virus (HDV) is an unusual, single-stranded, spherical RNA virus with a number of similarities to definite plant viral satellites and viroids. This virus requires hepadna virus helper functions for propagation in hepatocytes, and is an vital reason of acute and harsh chronic liver damage in several regions of the world.
Hepatitis E virus
Hepatitis E virus (HEV), the reason of enterically-transmitted non-A, non-B hepatitis, is another non-enveloped, single-stranded RNA virus, which shares many biophysical and biochemical features with caliciviruses. The the majority comparable genome to HEV is found in a plant virus, beet necrotic yellow vein virus, and there are similarities in the functional domains to rubella virus. Final taxonomic categorization is yet to be agreed upon.
Hepatitis E virus is an significant reason of large epidemics of keen hepatitis in the subcontinent of India, Central and Southeast Asia, the Middle East, parts of Africa and elsewhere. This virus is accountable for high mortality (15–20%), during pregnancy particularly during the third trimester.
Ref: Hepatitis Viruses