Hepatitis A Hepatitis A or
infectious jaundice is caused by hepatitis A virus (HAV), a
picornavirus transmitted by the
fecal-oral route often associated with ingestion of
contaminated food. It causes an acute form of hepatitis and does not have a chronic stage. A patient's
immune system makes
antibodies against HAV that confer
immunity against future infection. People with hepatitis A are advised to rest, stay hydrated and avoid alcohol. A vaccine is available that will prevent HAV infection for up to 10 years. Hepatitis A can be spread through personal contact, consumption of raw sea food, or drinking
contaminated water. This occurs primarily in
third world countries. The time between the infection and the start of the illness averages 28 days. (ranging from 15 to 50 days), Most patients recover fully within 2 months, although approximately 15% of affected people may experience continuous or
relapsing symptoms from six months to a year following initial
diagnosis.
Hepatitis B Hepatitis B is caused by the hepatitis B virus, a
hepadnavirus that can cause both acute and chronic hepatitis. Chronic hepatitis develops in the 15% of adults who are unable to eliminate the virus after an initial infection. Identified methods of transmission include contact with blood,
blood transfusion (now rare), unsanitary tattoos,
sex (through
sexual intercourse or contact with bodily fluids), or mother-to-child by
breast feeding; there is minimal evidence of
transplacental crossing. However, in about half of cases the source of infection cannot be determined. Blood contact can occur by sharing syringes in intravenous drug use, shaving accessories such as razor blades, or touching wounds on infected persons.
Needle-exchange programmes have been created in many countries as a form of prevention. Patients with chronic hepatitis B have antibodies against the virus, but not enough to clear the infected
liver cells. The continued production of virus and countervailing antibodies is a likely cause of the immune complex disease seen in these patients. A vaccine is available to prevent infection for life. Hepatitis B infections result in 500,000 to 1,200,000 deaths per year worldwide due to the complications of chronic hepatitis,
cirrhosis, and
hepatocellular carcinoma (HCC). Hepatitis B is
endemic in a number of (mainly South-East Asian) countries, making cirrhosis and hepatocellular carcinoma big killers. There are eight treatment options approved by the
U.S. Food and Drug Administration (FDA) available for persons with a chronic hepatitis B infection:
alpha-interferon,
pegylated interferon,
adefovir,
entecavir,
telbivudine,
lamivudine,
tenofovir disoproxil and
tenofovir alafenamide with a 65% rate of sustained response.
Hepatitis C Hepatitis C (originally "non-A non-B hepatitis") is caused by
hepatitis C virus (HCV), an
RNA virus of the family
Flaviviridae. HCV can be transmitted through contact with blood (including through sexual contact if the two parties' blood is mixed) and can also cross the
placenta. Hepatitis C usually leads to chronic hepatitis, culminating in
cirrhosis in some people. It usually remains
asymptomatic for decades. Patients with hepatitis C are susceptible to severe hepatitis if they contract either hepatitis A or B, so all persons with hepatitis C should be immunized against hepatitis A and hepatitis B if they are not already immune, and avoid alcohol. HCV can lead to the development of
hepatocellular carcinoma, however, only a minority of HCV-infected individuals develop cancer (1–4% annually), suggesting a complex interplay between viral gene expression and host and environmental factors to promote carcinogenesis. The risk is increased two-fold with active HBV coinfection and a 21% increase in mortality compared to those with latent HBV and HCV. HCV viral levels can be reduced to undetectable levels by a combination of
interferon and the
antiviral drug ribavirin. The genotype of the virus is the primary determinant of the rate of response to this treatment regimen, with genotype 1 being the most resistant. Hepatitis C is the most common chronic
bloodborne infection in the United States, and the leading cause of liver tranplants.
Hepatitis D Hepatitis D is caused by the hepatitis D virus (HDV), or hepatitis delta virus; it belongs to the genus
Deltavirus. HDV is similar to a
satellite virus as it can only propagate in the presence of the hepatitis B virus, depending on the helper function of HBV for its replication and expression. It has no independent life cycle, but can survive and replicate as long as HBV infection persists in the host body. It can only cause infection when encapsulated by hepatitis B virus surface antigens. The vaccine for hepatitis B protects against hepatitis D virus because of the latter's dependence on the presence of hepatitis B virus for it to replicate.
Hepatitis E Hepatitis E is caused by the Hepatitis E virus (HEV), from the family Hepeviridae. It produces symptoms similar to
hepatitis A, although it can take a
fulminant course in some patients, particularly pregnant women (mortality rate about 20%); chronic infections may occur in immune-compromised patients. It is more prevalent in the
Indian subcontinent. The virus is feco-orally transmitted and is usually self-limited.
Hepatitis F virus Hepatitis F virus (HFV) is a hypothetical virus linked to certain cases of hepatitis. Several hepatitis F virus candidates emerged in the 1990s, but none of these reports have been substantiated.
GB virus C The
GB virus C is a virus that is probably spread by blood and sexual contact. It was initially identified as Hepatitis G virus. There is very little evidence that this virus causes hepatitis, as it does not appear to replicate primarily in the liver. It is now classified as
Pegivirus hominis.
2022 hepatitis of unknown origin In 2022, several hundred cases of acute hepatitis of probable infectious origin were reported worldwide. As of May 2023, the virus causing these cases has not been identified, but an
adenovirus is suspected. == Relationship between hepatitis C virus and liver cancer ==