Hepatitis A is a liver infection caused by the Hepatitis A virus (HAV). The virus is spread when an uninfected (or unvaccinated) person eats or drinks something contaminated by the stool of an HAV-infected person: this is called faecal-oral transmission. The disease is closely associated with inadequate sanitation and poor personal hygiene. Unlike Hepatitis B and C, Hepatitis A infection does not cause chronic liver disease and is rarely fatal, but it can cause debilitating symptoms.
Hepatitis C is caused by the Hepatitis C virus (HCV). It usually spreads through contact with infected blood. It can also spread through sexual contact with an infected person or from mother to baby during childbirth. It can lead to serious complications including cirrhosis of liver and hepatocellular carcinoma (HCC).
Hepatitis D or Delta Hepatitis is caused by the Hepatitis Delta Virus (HDV), a defective RNA virus. HDV requires the help of a hepadnavirus like Hepatitis B Virus (HBV) for its own replication. HDV is transmitted percutaneously or sexually through contact with infected blood or blood products. Blood is potentially infectious during all phases of active hepatitis D infection. Peak infectivity probably occurs just before the onset of acute disease.
Hepatitis E (HEV) was not recognized as a distinct human disease until 1980. Hepatitis E is caused by infection with the Hepatitis E virus, a non-enveloped, positive-sense, single-stranded RNA virus. Although man is considered the natural host for HEV, antibodies to HEV or closely related viruses have been detected in primates and several other animal species. HEV is transmitted via the faecal-oral route. Hepatitis E is a waterborne disease, and contaminated water or food supplies have been implicated in major outbreaks. Consumption of faecally contaminated drinking water has given rise to epidemics and the ingestion of raw or uncooked shellfish has been the source of sporadic cases in endemic areas. There is a possibility of zoonotic spread of the virus, since several non-human primates, pigs, cows, sheep, goats and rodents are susceptible to infection. The risk factors for HEV infection are related poor sanitation in large areas of the world and HEV shedding in faeces.
Hepatitis G Virus (HGV) is also known as GB virus-C (GBV-C), as they were discovered about the same time and are thought to be different strains of the same virus. HGV/GBV-C, was first described in 1995-96. It is a single stranded RNA virus belonging to the Flaviviridae family.
HGV/GBV- C is often found in co-infections with other viruses, such as Hepatitis C virus (HCV), Hepatitis B virus (HBV) and Human Immunodeficiency Virus (HIV) .There is little proof that Hepatitis G (Hep G) causes serious liver disease at any age. It is possible that HGV/GBV-C may not be a true 'Hepatitis' virus.