Citizendia
Your Ad Here

Hepatitis A
Electron micrograph of hepatitis A virions.
Electron micrograph of hepatitis A virions. An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image
Virus classification
Group: Group IV ((+)ssRNA)
Family: Picornaviridae
Genus: Hepatovirus
Type species
Hepatitis A virus
Hepatitis A
Classification and external resources
ICD-10 B15.-
ICD-9 070.1
DiseasesDB 5757
MedlinePlus 000278
eMedicine med/991  ped/977
MeSH D006506

Hepatitis A, (formerly known as infectious hepatitis), is an acute infectious disease of the liver caused by Hepatitis A virus,[1] which is most commonly transmitted by the fecal-oral route via contaminated food or drinking water. Virus classification involves naming and placing Viruses into a taxonomic system An RNA virus is a Virus that has RNA (ribonucleic acid as its Genetic material. A Picornavirus is a Virus belonging to the family Picornaviridae. In biology a type is that which fixes a name to a Taxon. Depending on the nomenclature code which is applied to the organism in question a type may be a specimen Hepatitis A, (formerly known as infectious hepatitis) is an acute Infectious disease of the Liver caused by Hepatitis A virus which is The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings A00-A79 - Bacterial infections and other intestinal infectious diseases and STDs (A00-A09 Intestinal Infectious diseases ( The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books In Medicine, an acute disease is a disease with either or both of a rapid onset a short course (as opposed to a chronic course An infectious disease is a clinically evident Disease resulting from the presence of Pathogenic microbial agents including Pathogenic viruses Pathogenic The liver is a vital organ in the human body and is present in Vertebrates and some other animals The fecal-oral route (or alternatively the oral-fecal route or orofecal route) is a way Disease can be passed when fecal particles from one Every year, approximately 10 million people worldwide are infected with the virus. [2] The time between infection and the appearance of the symptoms, (the incubation period), is between two and six weeks and the average incubation period is 28 days. Incubation period is the Time elapsed between exposure to a Pathogenic Organism, or Chemical or radiation, and when Symptoms [3]

In developing countries, and in regions with poor hygiene standards, the incidence of infection with this virus approaches 100% and the illness is usually contracted in early childhood. Developing countries are countries that haven't reached Western-style standards of democratic government free market economy industrialization social programs and human rights guaranties Incidence is a measure of the risk of developing some new condition within a specified period of time Hepatitis A infection causes no clinical signs and symptoms in over 90% of these children and since the infection confers lifelong immunity, the disease is of no special significance to the indigenous population. In Europe, the United States and other industrialised countries, on the other hand, the infection is contracted primarily by susceptible young adults, most of whom are infected with the virus during trips to countries with a high incidence of the disease. In Epidemiology a susceptible individual (sometimes known simply as a susceptible is a member of a Population who is at risk of becoming infected by a disease if [3]

Hepatitis A does not have a chronic stage and does not cause permanent liver damage. In Medicine, a chronic disease is a Disease that is long-lasting or recurrent Following infection, the immune system makes antibodies against the hepatitis A virus that confer immunity against future infection. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily The disease can be prevented by vaccination and hepatitis A vaccine has been proved effective in controlling outbreaks worldwide. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease Hepatitis A Vaccine, (brand names include Havrix or Avaxim is a vaccine against the Hepatitis A virus [3]

Contents

Virus

The Hepatitis virus (HAV) is a Picornavirus; it is non-enveloped and contains a single-stranded RNA packaged in a protein shell. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable A Picornavirus is a Virus belonging to the family Picornaviridae. Many Viruses (eg influenza and many animal viruses have viral envelopes covering their protein Capsids The envelopes are typically derived from portions of An RNA virus is a Virus that has RNA (ribonucleic acid as its Genetic material. For the leaf bug see Miridae. A capsid is the protein shell of a virus. There is only one type of the virus. A serovar or serotype is a group of Microorganisms or Viruses based on their cell surface Antigens Serovars allow the epidemiologic classification

Pathogenesis

Following ingestion, HAV enters the bloodstream through the epithelium of the oropharynx or intestine. The Oropharynx ( oral part of the Pharynx) reaches from the Soft palate to the level of the Hyoid bone. [4] The blood carries the virus to its target, the liver, where it lives and multiplies within hepatocytes and Kupffer cells (i. Hepatocytes make up 70-80% of the Cytoplasmic mass of the Liver. Kupffer cells, also known as Browicz-Kupffer cells, are specialized Macrophages located in the Liver that form part of the Reticuloendothelial system e. , liver macrophages). There is no apparent virus-mediated cytotoxicity, and liver pathology is likely immune-mediated. Cytotoxicity is the quality of being toxic to cells Examples of toxic agents are a Chemical substance, an Immune cell or some types of Venom Virions are secreted into the bile and released in stool. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable Bile or gall is a bitter yellow or green Alkaline fluid secreted by Hepatocytes from the Liver of most Vertebrates In many species HAV is excreted in large quantities approximately 11 days prior to appearance of symptoms or anti-HAV IgM antibodies in the blood. Immunoglobulin M, or IgM for short is a basic Antibody that is present on B cells It is the primary antibody against A and B Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily The incubation period is 15-50 days, and mortality is less than 0. Incubation period is the Time elapsed between exposure to a Pathogenic Organism, or Chemical or radiation, and when Symptoms 5%.

Transmission

The virus spreads by the fecal-oral route and infections often occur in conditions of poor sanitation and overcrowding. The fecal-oral route (or alternatively the oral-fecal route or orofecal route) is a way Disease can be passed when fecal particles from one Hepatitis A can be transmitted by the parenteral route but very rarely by blood and blood products. In Pharmacology and Toxicology, a route Food-borne outbreaks are not uncommon,[5] and ingestion of shellfish cultivated in polluted water is associated with a high risk of infection. Shellfish is a Culinary and Fisheries term for those aquatic Invertebrate animals that are used as Food: various species of molluscs [6] Approximately 40% of all acute viral hepatitis is caused by HAV. [7] Infected individuals are infectious prior to onset of symptoms, roughly 10 days following infection. The virus is resistant to detergent, acid (pH 1), solvents (e. A detergent (as a noun is a material intended to assist Cleaning. g. , ether, chloroform), drying, and temperatures up to 60oC. Ether is a class of Organic compounds which contain an ether group — an Oxygen Atom connected to two (substituted Alkyl Chloroform, also known as trichloromethane and methyl trichloride, is a Chemical compound with formula C[[Hydrogen H]] Cl It can survive for months in fresh and salt water. Common-source (e. g. , water, restaurant) outbreaks are typical. Infection is common in children in developing countries, reaching 100% incidence, but following infection there is life-long immunity. HAV can be inactivated by: chlorine treatment (drinking water), formalin (0. Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl 35%, 37oC, 72 hours), peracetic acid (2%, 4 hours), beta-propiolactone (0. Peracetic acid ( peroxyacetic acid, or PAA) is a Chemical in the Organic peroxide family 25%, 1 hour), and UV radiation (2 μW/cm2/min). Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays

Symptoms

Early symptoms of hepatitis A infection can be mistaken for influenza, but some sufferers, especially children, exhibit no symptoms at all. Symptoms typically appear 2 to 6 weeks, (the incubation period ), after the initial infection. Incubation period is the Time elapsed between exposure to a Pathogenic Organism, or Chemical or radiation, and when Symptoms [8]

Symptoms can return over the following 6-9 months which include:[9]

Diagnosis

Serum IgG, IgM and ALT following Hepatitis A virus infection
Serum IgG, IgM and ALT following Hepatitis A virus infection

Although the virus is excreted in the feces towards the end of the incubation period, specific diagnosis is made by the detection of Hepatitis A virus specific IgM antibodies in the blood. Fever (also known as pyrexia, from the Greek pyretos meaning fire or a febrile response, from the Latin word Febris Abdominal pain can be one of the Symptoms associated with transient disorders or serious disease Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort In Medicine, diarrhea, also spelled diarrhoea (see spelling differences) is frequent loose or liquid Bowel movements Acute diarrhea Anorexia (deriving from the Greek "α(ν-" ( a(n-, a prefix that denotes absence + "όρεξη (orexe = appetite is the decreased sensation In the fields of Psychology and Psychiatry, the terms depression or depressed refer to both expected and pathologically chronic or severe Jaundice, also known as icterus (attributive adjective "icteric" is yellowish discoloration of the Skin, sclerae (whites of the eyes The right upper quadrant of the Human abdomen, often abbreviated as RUQ, is used to refer to a portion of the abdomen that allows doctors to Weight loss, in the context of Medicine or Health or Physical fitness, is a reduction of the total Body weight, due to a mean loss of fluid Incubation period is the Time elapsed between exposure to a Pathogenic Organism, or Chemical or radiation, and when Symptoms Immunoglobulin M, or IgM for short is a basic Antibody that is present on B cells It is the primary antibody against A and B Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily [10] IgM antibody is only present in the blood following an acute hepatitis A infection. It is detectable from one to two weeks after the initial infection and persists for up to 14 weeks. The presence of IgG antibody in the blood means that the acute stage of the illness is past and the person is immune to further infection. IgG antibody to HAV is also found in the blood following vaccination and tests for immunity to the virus are based on the detection of this antibody. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease [10]

During the acute stage of the infection, the liver enzyme alanine transferase (ALT) is present in the blood at levels much higher than is normal. Alanine transaminase or ALT is a Transaminase Enzyme ( It is also called serum glutamic pyruvic transaminase (SGPT or alanine aminotransferase The enzyme comes from the liver cells that have been damaged by the virus. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins [11]

Hepatitis A virus is present in the blood, (viremia), and feces of infected people up to two weeks before clinical illness develops. Viremia (UK viraemia) is a medical condition where Viruses enter the Bloodstream and hence have access to the rest of the body [11]

Epidemiology

Hepatitis A Distribution 2005
Hepatitis A Distribution 2005

HAV is found in the feces of infected persons and those who are at higher risk include travelers to developing countries where there is a higher incidence rate,[12] and those having sexual contact or drug use with infected persons. Developing countries are countries that haven't reached Western-style standards of democratic government free market economy industrialization social programs and human rights guaranties Incidence is a measure of the risk of developing some new condition within a specified period of time [13] There were 30,000 cases of Hepatitis A reported to the CDC in the U. S. in 1997. The agency estimates that there were as many as 270,000 cases each year from 1980 through 1999. [14]

HAV outbreaks still occur in and caused by poor hand hygiene among infected, sometimes symptomatic restaurant employees failing to wash their hands after toilet breaks. A toilet is a Plumbing fixture and disposal system primarily intended for the disposal of the bodily wastes: Urine and fecal matter.

Epidemics

The most widespread hepatitis A outbreak in America afflicted at least 640 people (killing four) in north-eastern Ohio and south-western Pennsylvania in late 2003. Ohio ( is a Midwestern state of the United States. As part of the Great Lakes region, Ohio has long been a cultural and geographical crossroads The Commonwealth of Pennsylvania ( often colloquially referred to as PA (its abbreviation by natives and Northeasterners is a state located in the Northeastern The outbreak was blamed on tainted green onions at a restaurant in Monaca, Pennsylvania. Monaca (pronounced mih-NAK-uh or muh-NAK-uh IPA or) is a borough in Beaver County, Pennsylvania, United States along the Ohio River, 25 [15] In 1988, 300,000 people in Shanghai, China were infected with HAV after eating clams from a contaminated river. [16]

See also

References

  1. ^ Ryan KJ, Ray CG (editors) (2004). Hepatitis (plural hepatitides) implies injury to the Liver characterized by the presence of Inflammatory cells in the tissue of Hepatitis C is a blood-borne infectious disease that is caused by the Hepatitis C virus ( HCV) affecting the Liver. Hepatitis E is a viral Hepatitis (liver inflammation caused by Infection with a Virus called hepatitis E virus ( HEV) Maurice Ralph Hilleman ( August 30 1919 - April 11 2005) was an American Microbiologist who specialized in Vaccinology Sherris Medical Microbiology, 4th ed. , McGraw Hill, 541–4. ISBN 0838585299.  
  2. ^ Thiel TK (1998). "Hepatitis A vaccination". Am Fam Physician 57 (7): 1500. PMID 9556642.  
  3. ^ a b c Connor BA (2005). "Hepatitis A vaccine in the last-minute traveler". Am. J. Med. 118 Suppl 10A: 58S–62S. doi:10.1016/j.amjmed.2005.07.018. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 16271543.  
  4. ^ Murray, P. r. , Rosenthal, K. S. , & Pfaller, M. A. (2005). Medical Microbiology," 5th ed. , Elsevier Mosby.
  5. ^ Brundage SC, Fitzpatrick AN (2006). "Hepatitis A". Am Fam Physician 73 (12): 2162–8. PMID 16848078.  
  6. ^ Lees D (2000). "Viruses and bivalve shellfish". Int. J. Food Microbiol. 59 (1-2): 81–116. doi:10.1016/S0168-1605(00)00248-8. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 10946842.  
  7. ^ Insert footnote text Murray, P. r. , Rosenthal, K. S. , & Pfaller, M. A. (2005). Medical Microbiology," 5th ed. , Elsevier Mosby.
  8. ^ Hepatitis A Symptoms. eMedicineHealth (2007-05-17). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1521 - Edward Stafford 3rd Duke of Buckingham, is executed for Treason. Retrieved on 2007-05-18. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1152 - Henry II of England marries Eleanor of Aquitaine.
  9. ^ Hepatitis A : Fact Sheet. Center for Disease Control (2007-08-09). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 48 BC - Caesar's civil war: Battle of Pharsalus - Julius Caesar decisively defeats Pompey at Pharsalus Retrieved on 2007-12-07. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 43 BC - Marcus Tullius Cicero assassinated 1696 - Connecticut Route 108, one of the oldest highways
  10. ^ a b Stapleton JT (1995). "Host immune response to hepatitis A virus". J. Infect. Dis. 171 Suppl 1: S9–14. PMID 7876654.  
  11. ^ a b Musana KA, Yale SH, Abdulkarim AS (2004). "Tests of liver injury". Clin Med Res 2 (2): 129–31. PMID 15931347.  
  12. ^ Chapter 4 - Hepatitis, Viral, Type A - Yellow Book | CDC Travelers' Health
  13. ^ Hepatitis A: Fact Sheet | CDC Viral Hepatitis
  14. ^ http://www.cdc.gov/Ncidod/diseases/hepatitis/a/global_hepA_epi.pdf
  15. ^ http://www.cdc.gov/mmwR/preview/mmwrhtml/mm5247a5.htm
  16. ^ Murray, P. r. , Rosenthal, K. S. , & Pfaller, M. A. (2005). Medical Microbiology," 5th ed. , Elsevier Mosby.

External links

Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books

Dictionary

hepatitis A

-noun

  1. an acute form of hepatitis, transmitted by the orofecal route.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic