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Viral hepatitis is
liver inflammation Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), poor appetite, vomiting, tiredness, abdominal pa ...
due to a
viral infection A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. Structural Characteristics Basic structural characteristics, ...
. It may present in acute form as a recent infection with relatively rapid onset, or in chronic form. The most common causes of viral hepatitis are the five unrelated hepatotropic viruses
hepatitis A Hepatitis A is an infectious disease of the liver caused by ''Hepatovirus A'' (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop the ...
, B, C, D, and E. Other viruses can also cause liver inflammation, including
cytomegalovirus ''Cytomegalovirus'' (''CMV'') (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order '' Herpesvirales'', in the family '' Herpesviridae'', in the subfamily '' Betah ...
,
Epstein–Barr virus The Epstein–Barr virus (EBV), formally called ''Human gammaherpesvirus 4'', is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. It is ...
, and
yellow fever Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. ...
. There also have been scores of recorded cases of viral hepatitis caused by herpes simplex virus.


Mode Of Transmission

Viral hepatitis is either transmitted through contaminated food or water (A, E) or via blood and body fluids (B, C). The viruses transmitted through water and food are mostly self-limited, resulting in acute illness with full resolution. The blood borne viruses (B, C) can cause both acute and chronic liver disease and can be transmitted from mother to child during birth, through contact with body fluids during sex, unsafe injections and through unscreened blood transfusions. The most common types of hepatitis can be prevented or treated. Hepatitis A and hepatitis B can be prevented by vaccination. Effective treatments for hepatitis C are available but costly. In 2013, about 1.5 million people died from viral hepatitis, most commonly due to hepatitis B and C. East Asia, in particular Mongolia, is the region most affected.


Hepatitis viruses

The most common cause of hepatitis is viral. Although the effects of various viruses are all classified under the disease
hepatitis Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes ( jaundice), poor appetite, vomiting, tiredness, abdominal ...
, these viruses are not all related.


Viral hepatitis types


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 Foodborne illness (also foodborne disease and food poisoning) is any illness resulting from the spoilage of contaminated food by pathogenic bacteria, viruses, or parasites that contaminate food, as well as prions (the agents of mad cow dise ...
. It causes an acute form of hepatitis and does not have a chronic stage. A patient's
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
makes
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of ...
against HAV that confer
immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity de ...
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. Strict personal hygiene and the avoidance of raw and unpeeled foods can help prevent an infection. Infected people excrete HAV with their
feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a rela ...
two weeks before and one week after the appearance of
jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
. 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 Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems engin ...
.


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 is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...
,
blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...
(now rare), unsanitary
tattoo A tattoo is a form of body modification made by inserting tattoo ink, dyes, and/or pigments, either indelible or temporary, into the dermis layer of the skin to form a design. Tattoo artists create these designs using several tattooing ...
s, sex (through
sexual intercourse Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal pene ...
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 programme A needle and syringe programme (NSP), also known as needle exchange program (NEP), is a social service that allows injecting drug users (IDUs) to obtain clean and unused hypodermic needles and associated paraphernalia at little or no cost. It ...
s 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 Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...
, and
hepatocellular carcinoma Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. It occurs in t ...
(HCC). Hepatitis B is
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
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 Pegylated interferon (PEG-IFN) is a class of medication that includes three different drugs as of 2012: * Pegylated interferon-alpha-2a * Pegylated interferon-alpha-2b * Pegylated interferon-beta-1a In these formulations, Polyethylene glycol (PEG ...
, adefovir, entecavir,
telbivudine Telbivudine is an antiviral drug used in the treatment of hepatitis B infection. It is marketed by Swiss pharmaceutical company Novartis under the trade names Sebivo (European Union) and Tyzeka (United States). Clinical trials have shown it to be ...
, lamivudine, tenofovir disoproxil and
tenofovir alafenamide Tenofovir alafenamide, sold under the brand name Vemlidy, is a hepatitis B virus (HBV) nucleotide reverse transcriptase inhibitor medication for the treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver dise ...
with a 65% rate of sustained response.


Hepatitis C

''Hepatitis C'' (originally "non-A non-B hepatitis") is caused by
hepatitis C virus The hepatitis C virus (HCV) is a small (55–65 nm in size), enveloped, positive-sense single-stranded RNA virus of the family '' Flaviviridae''. The hepatitis C virus is the cause of hepatitis C and some cancers such as liver cancer (hepatoc ...
(HCV), an
RNA virus An RNA virus is a virusother than a retrovirusthat has ribonucleic acid ( RNA) as its genetic material. The nucleic acid is usually single-stranded RNA (ssRNA) but it may be double-stranded (dsRNA). Notable human diseases caused by 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 The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...
. Hepatitis C usually leads to chronic hepatitis, culminating in
cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...
in some people. It usually remains
asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered a ...
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 Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide. It occurs in t ...
, 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 Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten th ...
and the
antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do n ...
ribavirin Ribavirin, also known as tribavirin, is an antiviral medication used to treat RSV infection, hepatitis C and some viral hemorrhagic fevers. For hepatitis C, it is used in combination with other medications such as simeprevir, sofosbuvir, pe ...
. The genotype of the
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...
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 blood-borne infection in the United States.


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 Hepatitis A is an infectious disease of the liver caused by ''Hepatovirus A'' (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop the ...
, although it can take a
fulminant Fulminant () is a medical descriptor for any event or process that occurs suddenly and escalates quickly, and is intense and severe to the point of lethality, i.e., it has an explosive character. The word comes from Latin ''fulmināre'', to stri ...
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 Indian subcontinent is a physiographical region in Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian Ocean from the Himalayas. Geopolitically, it includes the countries of Bangladesh, Bhutan, In ...
. 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 GB virus C.


2022 hepatitis of unknown origin

In 2022, several hundred cases of acute hepatitis of probable infectious origin were reported worldwide. As of May 2022, the virus causing these cases has not been identified, but an
adenovirus Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from ...
is suspected.Adenovirus probable cause of mysterious child hepatitis.
BBC News, 25 April 2022. Retrieved 25 April 2022.


Relationship between hepatitis C virus and liver cancer

Hepatitis C virus (HCV) can cause acute and chronic infections that are a major cause of hepatocellular carcinoma (HCC), advanced hepatic fibrosis and cirrhosis. HCC is a major cause of death in patients with chronic HCV infection. Regarding the pathogenesis of HCC associated with HCV, that virus may play direct or indirect roles. A major risk for the development of HCC is persistent infection with HCV, and the highest risk for HCC development is associated with co-infection of HBV with HDV, HCV or HIV. Risk factors that can lead to the development of HCC in those with chronic HCV include synchronous liver diseases, viral genotype, diabetes mellitus, and obesity. Lifestyle factors such as liver steatosis, smoking, and alcohol use can accelerate progression to HCC and liver decompensation in patients with HCV.Persico M, Bruno S, Costantino A, Mazza M, Almasio PL. The impact of antiviral therapy and the influence of metabolic cofactors on the outcome of chronic HCV infection. Int J Hepatol. 2011;2011:314301. doi: 10.4061/2011/314301. The purpose of HCV treatment is to eliminate the infection, reduce the transmission to other people and decrease the risk of HCC development.


Other viruses

The virus first known to cause hepatitis was the yellow fever virus, a mosquito-borne flavivirus. Other viruses than can cause hepatitis include: * Adenoviruses *
Arenavirus An arenavirus is a bisegmented ambisense RNA virus that is a member of the family ''Arenaviridae''. These viruses infect rodents and occasionally humans. A class of novel, highly divergent arenaviruses, properly known as reptarenaviruses, have ...
es: Guanarito virus,
Junín virus ''Argentinian mammarenavirus'', better known as the ''Junin virus'' or ''Junín virus'' (JUNV), is an arenavirus in the ''Mammarenavirus'' genus that causes Argentine hemorrhagic fever (AHF). The virus took its original name from the city of Jun ...
, Lassa fever virus, Lujo virus, Machupo virus, and Sabiá virus * Bunyaviruses: Crimean–Congo hemorrhagic fever virus, Dobrava virus, Hantaan virus, Puumala virus,
Rift Valley fever virus In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben wi ...
, and
Seoul virus ''Seoul orthohantavirus'' (SEOV) is a member of the ''Orthohantavirus'' family of rodent-borne viruses and is one of the 4 hantaviruses that are known to be able to cause Hantavirus hemorrhagic fever with renal syndrome (HFRS).US Centers for Dise ...
*
Coronavirus Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the co ...
: severe acute respiratory syndrome virus * Erythrovirus:
Parvovirus B19 Primate erythroparvovirus 1, generally referred to as B19 virus (B19V), parvovirus B19 or sometimes erythrovirus B19, is the first (and until 2005 the only) known human virus in the family '' Parvoviridae'', genus ''Erythroparvovirus''; it measu ...
*
Filovirus ''Filoviridae'' () is a family of single-stranded negative-sense RNA viruses in the order '' Mononegavirales''. Two members of the family that are commonly known are Ebola virus and Marburg virus. Both viruses, and some of their lesser known ...
es: Ebola virus and
Marburg virus Marburg virus (MARV) is a hemorrhagic fever virus of the '' Filoviridae'' family of viruses and a member of the species '' Marburg marburgvirus'', genus '' Marburgvirus''. It causes Marburg virus disease in primates, a form of viral hemorrhagi ...
* Flaviviruses:
dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...
, Kyasanur Forest disease virus,
Omsk hemorrhagic fever Omsk hemorrhagic fever is a viral hemorrhagic fever caused by a Flavivirus. It was found in Siberia and was named for an outbreak in the city of Omsk. First records of the new virus appeared around 1940–1943. Signs and symptoms There are a num ...
virus, and
yellow fever Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. ...
virus * Herpesviruses:
cytomegalovirus ''Cytomegalovirus'' (''CMV'') (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order '' Herpesvirales'', in the family '' Herpesviridae'', in the subfamily '' Betah ...
,
Epstein–Barr virus The Epstein–Barr virus (EBV), formally called ''Human gammaherpesvirus 4'', is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. It is ...
, varicella-zoster virus, human herpesvirus 6,
human herpesvirus 7 ''Human betaherpesvirus 7'' (HHV-7) is one of nine known members of the ''Herpesviridae'' family that infects humans. HHV-7 is a member of ''Betaherpesvirinae'', a subfamily of the ''Herpesviridae'' that also includes HHV-6 and '' Cytomegaloviru ...
, and human herpesvirus 8 * Orthomyxoviruses:
influenza Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptom ...
* Picornaviruses:
echovirus Echovirus is a polyphyletic group of viruses associated with enteric disease in humans. The name is derived from "enteric cytopathic human orphan virus". These viruses were originally not associated with disease, but many have since been identif ...
* Reovirus: Colorado tick fever virus, reovirus 3 Additionally, a casual role between the virus KIs-V and hepatitis is suspected based on a 2011 study that isolated KIs-V from four patients with raised serum
alanine transferase Alanine transaminase (ALT) is a transaminase enzyme (). It is also called alanine aminotransferase (ALT or ALAT) and was formerly called serum glutamate-pyruvate transaminase or serum glutamic-pyruvic transaminase (SGPT) and was first character ...
s without other known cause.


References


External links

{{DEFAULTSORT:Viral Hepatitis Diseases of liver Infectious causes of cancer Articles containing video clips