Alcoholic hepatitis Excessive alcohol consumption is a significant cause of hepatitis and is the most common cause of cirrhosis in the U. This ranges in order of severity and reversibility from alcoholic steatosis least severe, most reversiblealcoholic hepatitiscirrhosis, and liver cancer most severe, least reversible. The industrial toxin carbon tetrachloride and the wild mushroom Amanita phalloides are other known hepatotoxins.
General Concepts Viral hepatitis has emerged as a major public health problem throughout the world affecting several hundreds of millions of people. Viral hepatitis is a cause of considerable morbidity and mortality in the human population, both from acute 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 most common cancers worldwide, is closely associated with hepatitis B, and at least in some regions of the world with hepatitis C virus. The hepatitis viruses include a range of unrelated and often highly unusual human pathogens.
Hepatitis A virus Hepatitis A virus HAVclassified as hepatovirus, is a small, unenveloped symmetrical RNA virus which shares many of the characteristics of the picornavirus family, and is the cause of infectious or epidemic hepatitis transmitted by the fecal-oral route. Hepatitis B virus is endemic 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 occur in other mammals including woodchucks, beechy ground squirrels and ducks. Hepatitis C virus Hepatitis C virus HCVis an enveloped single-stranded RNA virus which appears to be distantly related possibly in its evolution to flaviviruses, although hepatitis C is not transmitted by arthropod vectors.
Several 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 primary liver cancer in some countries.
This virus requires hepadna virus helper functions for propagation in hepatocytes, and is an important cause of acute and severe chronic liver damage in many regions of the world.
Hepatitis E virus Hepatitis E virus HEVthe cause 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 most similar 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 classification is yet to be agreed upon. Hepatitis E virus is an important cause of large epidemics of acute hepatitis in the subcontinent of India, Central and Southeast Asia, the Middle East, parts of Africa and elsewhere.
The GB hepatitis viruses were cloned recently and preliminary genomic characterization shows that they are related to other positive-stranded RNA viruses with local regions of sequence identity with various flaviviruses.
Phylogenetic analysis of genomic sequences showed that these viruses are not genotypes of the hepatitis C virus. Hepatitis A Outbreaks of jaundice have been frequently described for many centuries and the term infectious hepatitis was coined in to describe the epidemic form of the disease.
Hepatitis A virus HAV is spread by the fecal-oral route and continues to be endemic throughout the world and hyperendemic in areas with poor standards of sanitation and hygiene.
For example, an outbreak of hepatitis A associated with the consumption of clams in Shanghai in resulted in almostcases. Hepatitis A has an incubation period of about four weeks.
The virus replicates in the liver. Relatively large quantities of virus are shed in the feces during the incubation period before the onset of clinical symptoms, and a brief viremia occurs. The severity of illness ranges from the asymptomatic to anicteric or icteric hepatitis.
The virus is non-cytopathic when grown in cell culture. Its pathogenicity in vivo, which involves necrosis of parenchymal cells and histiocytic periportal inflammation, may be mediated by cellular immune responses.
By the time of onset of symptoms, excretion of virus in the feces has declined and may have ceased and anti-HAV IgM increases in titer. Distinctive properties Electron microscopic examination of concentrates of filtered fecal extracts from patients during the early stages of infection reveals 27 nm icosahedral particles typical of the Picornaviridae Fig.
HAV was classified in in the genus Enterovirus as enterovirus 72 of the family Picornaviridae, on the basis of its biophysical and biochemical characteristics, including stability at low pH.
After the entire nucleotide sequence of the viral genome was determined, comparison with other picornavirus sequences revealed limited homology to the enteroviruses, and the virus is now considered as a separate genus, hepatovirus.
Figure Hepatitis A virus particles found in fecal extracts by immunoelectron microscopy. Both full and empty particles are present.Acute infection with hepatitis B virus is associated with acute viral hepatitis, an illness that begins with general ill-health, loss of appetite, nausea, vomiting, body aches, mild fever, and dark urine, and then progresses to development of jaundice.
The hepatitis B virus is one of the causes of hepatitis, which is an inflammation of the liver cells. There are 8 different genotypes of the hepatitis B virus (hepatitis B type a toy h).
The liver is a vital organ with remarkable regenerative abilities.
Epidemiological and Clinical Features of Hepatitis B Virus Genotypes among Immigrants in Southern the clinical description of the hepatitis bvirus HBVQU: Diagnosis of acute or chronic hepatitis B virus (HBV) infection is based on the presence of HBV serologic markers such as hepatitis B surface antigen (HBsAg Electron microscopy gave the.
Infants born to HBsAg-positive mothers should receive hepatitis B immune globulin (HBIG) and the first dose of hepatitis B vaccine within 12 hours of birth, followed by the second and third doses of vaccine at 1 and 6 months of age, respectively.
Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). For some people, hepatitis B infection becomes chronic, meaning it lasts more than six months. Having chronic hepatitis B increases your risk of developing liver failure, liver cancer or cirrhosis — a .
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 endemic in the human population and hyperendemic in many parts of the world. A .