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hepatitis A

 
Medical Encyclopedia: Hepatitis A
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Definition

Hepatitis A is an inflammation of the liver caused by a virus, the hepatitis A virus (HAV). It varies in severity, running an acute course, generally starting within two to six weeks after contact with the virus, and lasting no longer than two or three months. HAV may occur in single cases after contact with an infected relative or sex partner. Alternately, epidemics may develop when food or drinking water is contaminated by the feces of an infected person.

Description

Hepatitis A was previously known as infectious hepatitis because it spread relatively easily from those infected to close household contacts. Once the infection ends, there is no lasting, chronic phase of illness. However it is not uncommon to have a second episode of symptoms about a month after the first; this is called a relapse, but it is not clear that the virus persists when symptoms recur. Both children and adults may be infected by HAV. Children are the chief victims, but very often have no more than a flu-like illness or no symptoms at all (socalled "subclinical" infection), whereas adults are far likelier to have more severe symptoms.

Epidemics of HAV infection can infect dozens and even hundreds (or, on rare occasions, thousands) of persons.

In the public's mind, outbreaks of hepatitis A usually are linked with the eating of contaminated food at a restaurant. It is true that food-handlers, who may themselves have no symptoms, can start an alarming, widespread epidemic. Many types of food can be infected by sewage containing HAV, but shellfish, such as clams and oysters, are common culprits.

Apart from contaminated food and water, certain groups are at increased risk of getting infectious hepatitis:

  • Children at day care centers make up an estimated 14–40% of all cases of HAV infection in the United States. Changing diapers transmits infection through fecal-oral contact. Toys and other objects may remain contaminated for some time. Often a child without symptoms brings the infection home to siblings and parents.
  • Troops living under crowded conditions at military camps or in the field. During World War II there were an estimated five million cases in German soldiers and civilians.
  • Anyone living in heavily populated and squalid conditions, such as the very poor and those placed in refugee or prisoner-of-war camps.
  • Homosexual men are increasingly at risk of HAV infection from oral-anal sexual contact.
  • Travelers visiting an area where hepatitis A is common are at risk of becoming ill.

— Larry I. Lutwick, MD


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Dictionary: hepatitis A
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n.
An infection of the liver that is caused by an RNA virus, is transmitted by ingestion of infected food and water, and has a shorter incubation and generally milder symptoms than hepatitis B. Also called infectious hepatitis.


Dental Dictionary: infectious hepatitis
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n
IH, type A hepatitis

A viral hepatitis that is frequently epidemic in nature and has an incubation period of 1 to 4 or even 7 weeks. It is usually transmitted by the virus in fecal matter but may be transmitted by human serum (transfusions, lacerations, needle punctures).

Children's Health Encyclopedia: Hepatitis A
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Definition

Hepatitis A is a liver disease caused by the hepatitis A virus (HAV).

Description

Hepatitis A is a form of viral hepatitis also known as infectious hepatitis, due to its ability to be spread through personal contact. Hepatitis A is a milder liver disease than hepatitis B, and asymptomatic infections are very common, especially in children. Hepatitis A does not cause a carrier state or chronic liver disease. Once the infection ends, there is no lasting phase of illness. However, it is not uncommon to have a second episode of symptoms about a month after the first; this is called a relapse.

Transmission

HAV is found in the stool (feces) of persons infected with hepatitis A. HAV is usually spread from person to person by putting something in the mouth that has been contaminated with the stool of a person infected with hepatitis A. This is called fecal-oral transmission. Thus, the virus spreads more easily in areas where there are poor sanitary conditions or where good personal hygiene is not observed. Most infections result from contact with a household member who has hepatitis A. Blood-borne infection has been documented but is rare in the United States. The common modes of transmission of hepatitis A are as follows:

  • consuming food made by someone who touched infected feces
  • drinking water that is contaminated by infected feces (a problem in communities with poor sewage treatment facilities)
  • touching an infected person's feces, which may occur with poor hand washing
  • having direct contact in large daycare centers, especially where there are children in diapers
  • being a resident of states in which hepatitis A is more common
  • sexual contact with an infected perslin

Demographics

Hepatitis A has a worldwide distribution and is endemic in most countries. However, the incidence of the disease is declining in developed countries. There is a very high incidence in developing countries and rural areas. For example, in rural areas of South Africa, the rate of infection is 100 percent.

According to the Centers for Disease Control, HAV infects up to 200,000 Americans each year with the highest rate of hepatitis A being among children five to 14 years of age. Almost 30 percent of reported cases of hepatitis A occur among children under 15 years of age, chiefly because they are frequently in close contact with other children in school and at daycare. Approximately 15 percent of reported cases of hepatitis A occur among children or employees in daycare centers. The states with the highest incidence of hepatitis A account for 50 percent of the reported cases. According to the American Academy of Pediatrics, 11 states have a rate of HAV infection that is at least twice the national average, or 20 cases per every 100,000 people. The states are: Arizona, Alaska, California, Idaho, Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Utah, and Washington.

Causes and Symptoms

Hepatitis A is caused by HAV, also called Entero-virus 72, which was identified in 1973. The virus has an incubation period of three to five weeks. It enters the body via the gut and replicates in the digestive tract and spreads to infect the liver, where it multiplies. HAV is excreted in the stools for two weeks preceding the onset of symptoms.

Persons with hepatitis A may not have signs or symptoms of the disease and older persons are more likely to have symptoms than children. If present, symptoms are non-specific and usually include fever, tiredness, loss of appetite, nausea, abdominal discomfort, dark urine, and jaundice (yellowing of the skin and eyes). Symptoms usually last less than two months, but some persons can be ill for as long as six months.

When to Call the Doctor

Parents should call the doctor immediately if any of the following occurs:

  • A child has changes in symptoms, is confused, is difficult to wake up, is lethargic (sluggish), or irritable.
  • A child is unable to drink fluids.
  • A child's skikn is yellow in color.
  • A child has signs of dehydration such as no urine in over eight hours or a dry mouth.
  • A child starts to look very sick.

Diagnosis

Hepatitis A symptoms often go unrecognized because they are not specific to hepatitis A, thus a blood test (IgM anti-HAV) is required to diagnose HAV infection. This test detects a specific antibody, called hepatitis A IgM, that develops when HAV is present in the body.

Treatment

No specific treatment is available for hepatitis A. However, the following guidelines are often recommended:

  • Fluids and diet. The best treatment is to make sure that the child drinks a lot of fluids and eats well.
  • Rest. The child should rest while he or she has fever or jaundice. When fever and jaundice are gone, activity may be gradually increased as with the healthcare provider's approval.
  • Medications. The body's immune system fights the HAV infection. Once the child recovers from hepatitis A, the virus leaves the body. Medications, prescription or nonprescription, should not be given without consulting the doctor.

Nutritional Concerns

Parents should ensure that their infected child has a well-balanced diet. Children with advanced liver disease need to follow specific diets issued by the treating physician. However, most children are not in this category, and no special diet is currently recommended for them, except that they should avoid eating fatty foods because the body has difficulty digesting fat when the liver is not working well.

However, adequate protein intake is important to regenerate liver cells. Children without liver cirrhosis require about 2–3 grams of protein per kilogram of body weight. Children with cirrhosis need an individual nutrition plan from their pediatric specialist or nutritionist.

Prognosis

Viral hepatitis symptoms usually last three weeks to two months but may last up to six months. Children may return to daycare one week after symptoms first appear, with the doctor's permission. Most children with hepatitis get better naturally without liver problems later in life. However, some children do have subsequent liver problems. For this reason, it is important to keep in close touch with the treating physician and to keep all followup appointments. Chronic, or relapsing, infection does not occur with hepatitis A. In the United States, serious complications are infrequent, and deaths are very rare.

Prevention

According to the Centers for Disease Control and Prevention (CDC), routine vaccination of children is the most effective way to lower the incidence of hepatitis A nationwide. The CDC encourages implementation of routine hepatitis A vaccination programs for children in the 17 states which have the highest rates of hepatitis A. Hepatitis A vaccine has been licensed in the United States for use in persons two years of age and older. The vaccine is recommended (before exposure to hepatitis A virus) for persons who are more likely to get hepatitis A virus infection or are more likely to get seriously ill if they do get hepatitis A. The vaccines licensed in the United States as of 2004 were HAVRIX(r) (manufactured by Glaxo SmithKline) and VAQTA(r) (manufactured by Merck & Co., Inc).

Parents should teach their children always to wash their hands with soap and water after using the bathroom and before preparing and eating food. Travelers should avoid water and ice if unsure of their purity, or they can boil water for one minute before drinking it.

Short-term protection against hepatitis A is available from immune globulin, a preparation of antibodies that can be given before exposure for short-term protection against hepatitis A and for persons who have already been exposed to HAV. It can be given before and within two weeks after suspected contact with the virus.

Parental Concerns

The best way to prevent exposure to HAV is good habits in washing hands. Children should wash their hands every time they go to the bathroom. Good handwashing should be enforced at home and at daycare facilities. It is also very important to keep a clean environment, such as clean toilets, bathrooms, and clothing. If a child is diagnosed with HAV, other family members should be treated to prevent spread of the disease. The healthcare provider can help parents to plan treatment for the entire family.

See also Hepatitis B; Vaccination.

Resources

Books

Achord, James. Understanding Hepatitis. Jackson: University of Mississippi Press, 2002.

Berkman, Alan, and N. Bakalar. Hepatitis A to G: The Facts You Need to Know About All the Forms of This Dangerous Disease. Clayton, Australia: Warner Books, 2000.

Periodicals

Arya, G., and W. F. Balistreri. "Pediatric liver disease in the United States: Epidemiology and impact." Journal of Gastroenterology & Hepatology 17, no. 5 (May 2002):521–25.

Averhoff, F. et al. "Control of Hepatitis A Through Routine Vaccination of Children." Journal of the American Medical Association 286, no. 23 (December 2001): 2968–73.

Ferreira, Cristina T. et al. "Immunogenicity and Safety of Hepatitis A Vaccine in Children with Chronic Liver Disease." Journal of Pediatric Gastroenterology & Nutrition 37, no. 3 (September 2003): 258–61.

Jenson, Hal B. "The changing picture of hepatitis A in the United States." Current Opinion in Pediatrics 16, no. 1 (February 2004): 89–93.

Shulman, Stanford T. "The History of Pediatric Infectious Diseases." Pediatric Research 55, no. 1 (January 2004): 163–176.

Murdoch, David L., et al. "Combined Hepatitis A and B Vaccines: A Review of Their Immunogenicity and Tolerability." Drugs 40, no. 5–6 (May-June 2004): 265–69.

Organizations

American Liver Foundation (ALF). 75 Maiden Lane, Suite 603, New York, NY 10038–4810. Web site: www.liverfoundation.org.

National Center for Infectious Diseases (NCID). Centers for Disease Control and Prevention, Mailstop C-14, 1600 Clifton Road, Atlanta, GA 30333. Web site: www.cdc.gov/ncidod.

Hepatitis Foundation International (HFI). 504 Blick Drive, Silver Spring, MD 20904–2901. Web site: www.liverfoundation.org.

Web Sites

"Viral Hepatitis A Homepage." NCID. Available online at www.cdc.gov/ncidod/diseases/hepatitis/a/index.htm (accessed October 22, 2004.) "What I need to know about Hepatitis A Homepage." NIHNDDIC. Available online at (accessed October 22, 2004).

[Article by: Monique Laberge, Ph.D.]


Encyclopedia of Public Health: Hepatitis A Vaccine
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Hepatitis A vaccine is prepared by inactivating hepatitis A viruses grown in cell culture. Two injections at intervals of approximately six months induce protection in 90 percent or more of recipients. Whether booster doses will be needed is not yet known. Soreness at the injection site is common and headaches are reported in up to 16 percent of recipients, but no significant adverse events are known to be caused by hepatitis A vaccine. The vaccine is recommended for persons at increased risk for hepatitis A, including children living in areas of the United States with high incidence of disease, persons of any age traveling to or working in countries with high levels of infection, and persons at increased risk due to occupation or behavior (e.g., injection drug use, men who have sex with other men).

(SEE ALSO: Communicable Disease Control; Immunizations)

Bibliography

Centers for Disease Control and Prevention (1999). "Prevention of Hepatitis A Through Active or Passive Immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP)." Morbidity and Mortality Weekly Report 48:1–37.

— ALAN R. HINMAN


Wikipedia: Hepatitis A
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Hepatitis A
Electron micrograph of hepatitis A virions.
Virus classification
Group: Group IV ((+)ssRNA)
Family: Picornaviridae
Genus: Hepatovirus
Species: Hepatitis A virus
Hepatitis A
Classification and external resources
ICD-10 Bb 15.htm+ b 15 15. -
ICD-9 070.1 070.1
DiseasesDB 5757
MedlinePlus 000278
eMedicine med/991 ped/topic 977.htm# ped/ 977
MeSH D006506

Hepatitis A (formerly known as infectious hepatitis) is an acute infectious disease of the liver caused by the hepatitis A virus (HAV),[1] which is most commonly transmitted by the fecal-oral route via contaminated food or drinking water. 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.[3]

In developing countries, and in regions with poor hygiene standards, the incidence of infection with this virus is high[4] and the illness is usually contracted in early childhood. HAV has also been found in samples taken to study ocean water quality.[5] Hepatitis A infection causes no clinical signs and symptoms in over 90% of infected 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 industrialized 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.[3]

Hepatitis A does not have a chronic stage, is not progressive, and does not cause permanent liver damage. Following infection, the immune system makes antibodies against HAV that confer immunity against future infection. The disease can be prevented by vaccination, and hepatitis A vaccine has been proven effective in controlling outbreaks worldwide.[3]

Contents

Signs and 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.[6]

Symptoms can return over the following 6–9 months and include:[7]

Virology

The Hepatitis virus (HAV) is a Picornavirus; it is non-enveloped and contains a single-stranded RNA packaged in a protein shell. There is only one serotype of the virus, but multiple genotypes exist.

Pathogenesis

Following ingestion, HAV enters the bloodstream through the epithelium of the oropharynx or intestine.[8] The blood carries the virus to its target, the liver, and multiplies within hepatocytes and Kupffer cells (i.e., liver macrophages). There is no apparent virus-mediated cytotoxicity, and liver pathology is likely immune-mediated. Virions are secreted into the bile and released in stool. HAV is excreted in large quantities approximately 11 days prior to appearance of symptoms or anti-HAV IgM antibodies in the blood. The incubation period is 15–50 days, and mortality is less than 0.5%.

Diagnosis

Serum IgG, IgM and ALT following Hepatitis A virus infection

Although HAV is excreted in the feces towards the end of the incubation period, specific diagnosis is made by the detection of HAV-specific IgM antibodies in the blood.[9] 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.[9]

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. The enzyme comes from the liver cells that have been damaged by the virus.[10]

Hepatitis A virus is present in the blood, (viremia), and feces of infected people up to two weeks before clinical illness develops.[10]

Prevention

For about the vaccine, its properties, and its application, see Hepatitis A vaccine.

Hepatitis A can be prevented by vaccination, good hygiene and sanitation.[1][11] Hepatitis A is also one of the main reasons not to surf or go in the ocean after rains in coastal areas that are known to have bad runoff.[5]

The vaccine protects against HAV in more than 95% of cases for 10 years. It contains inactivated Hepatitis A virus providing active immunity against a future infection.[12][13] The vaccine was first phased in 1996 for children in high-risk areas, and in 1999 it was spread to areas with elevating levels of infection.[14]

The vaccine is given in two doses in the muscle of the upper arm. The first dose provides protection two to four weeks after initial vaccination; the second booster dose, given six to twelve months later, provides protection for up to twenty years.[12][14]

Treatment

There is no specific treatment for hepatitis A. Sufferers are advised to rest, avoid fatty foods and alcohol (these may be poorly tolerated for some additional months during the recovery phase and cause minor relapses), eat a well-balanced diet, and stay hydrated. Approximately 15% of people diagnosed with hepatitis A may experience one or more symptomatic relapse(s) for up to 24 months after contracting this disease.[citation needed]

Prognosis

The United States Centers for Disease Control and Prevention (CDC) in 1991 reported a low mortality rate for hepatitis A of 4 deaths per 1000 cases for the general population but a higher rate of 17.5 per 1000 in those aged 50 and over. Death usually occurs when the patient contracts Hepatitis A while already suffering from another form of Hepatitis, such as Hepatitis B or Hepatitis C, or AIDS.[citation needed]

Young children who are infected with hepatitis A typically have a milder form of the disease, usually lasting from 1–3 weeks, whereas adults tend to experience a much more severe form of the disease.[citation needed]

Epidemiology

Prevalence

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,[15] and those having sexual contact or drug use with infected persons.[16] 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 2000.[17]

Transmission

The virus spreads by the fecal-oral route and infections often occur in conditions of poor sanitation and overcrowding. Hepatitis A can be transmitted by the parenteral route but very rarely by blood and blood products. Food-borne outbreaks are not uncommon,[18] and ingestion of shellfish cultivated in polluted water is associated with a high risk of infection.[19] Approximately 40% of all acute viral hepatitis is caused by HAV.[8] 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.g., ether, chloroform), drying, and temperatures up to 60oC. 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 (0.35%, 37oC, 72 hours), peracetic acid (2%, 4 hours), beta-propiolactone (0.25%, 1 hour), and UV radiation (2 μW/cm2/min).

Cases

The most widespread hepatitis A outbreak in the United States afflicted at least 640 people (killing four) in north-eastern Ohio and south-western Pennsylvania in late 2003. The outbreak was blamed on tainted green onions at a restaurant in Monaca, Pennsylvania.[20] In 1988, 300,000 people in Shanghai, China were infected with HAV after eating clams from a contaminated river.[8]

See also

References

  1. ^ a b Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 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. PMID 16271543. http://linkinghub.elsevier.com/retrieve/pii/S0002-9343(05)00611-X. 
  4. ^ Steffen R (October 2005). "Changing travel-related global epidemiology of hepatitis A". Am. J. Med. 118 Suppl 10A: 46S–49S. doi:10.1016/j.amjmed.2005.07.016. PMID 16271541. http://linkinghub.elsevier.com/retrieve/pii/S0002-9343(05)00609-1. Retrieved 2008-12-20. 
  5. ^ a b Seven Surfing Sicknesses, .
  6. ^ "Hepatitis A Symptoms". eMedicineHealth. 2007-05-17. http://www.emedicinehealth.com/hepatitis_a/page3_em.htm#Hepatitis%20A%20Symptoms. Retrieved 2007-05-18. 
  7. ^ "Hepatitis A : Fact Sheet". Center for Disease Control. 2007-08-09. http://www.cdc.gov/Ncidod/diseases/hepatitis/a/fact.htm. Retrieved 2007-12-07. 
  8. ^ a b c Murray, P. r., Rosenthal, K. S., & Pfaller, M. A. (2005). Medical Microbiology," 5th ed., Elsevier Mosby.
  9. ^ a b Stapleton JT (1995). "Host immune response to hepatitis A virus". J. Infect. Dis. 171 Suppl 1: S9–14. PMID 7876654. 
  10. ^ a b Musana KA, Yale SH, Abdulkarim AS (2004). "Tests of liver injury". Clin Med Res 2 (2): 129–31. doi:10.3121/cmr.2.2.129. PMID 15931347. http://www.clinmedres.org/cgi/pmidlookup?view=long&pmid=15931347. 
  11. ^ http://www.nhs.uk/Conditions/Hepatitis-A/Pages/Prevention.aspx?url=Pages/What-is-it.aspx
  12. ^ a b "Avaxim". NetDoctor.co.uk. http://www.netdoctor.co.uk/medicines/100003051.html. Retrieved 2007-03-12. 
  13. ^ Hammitt, LL; Bulkow, L; Hennessy, TW; Zanis, C; Snowball, M; Williams, JL; Bell, BP; Mcmahon, BJ (2008). "Persistence of antibody to Hepatitis A virus 10 years after vaccination among children and adults". J Infect Dis 198 (12): 1776–1782. doi:10.1086/593335. PMID 18976095. 
  14. ^ a b "Hepatitis A Vaccine: What you need to know". Vaccine Information Statement. CDC. 2006-03-21. http://www.cdc.gov/vaccines/pubs/vis/downloads/vis-hep-a.pdf. Retrieved 2007-03-12. 
  15. ^ Chapter 4 - Hepatitis, Viral, Type A - Yellow Book | CDC Travelers' Health
  16. ^ Hepatitis A: Fact Sheet | CDC Viral Hepatitis
  17. ^ Index | CDC Viral Hepatitis
  18. ^ Brundage SC, Fitzpatrick AN (2006). "Hepatitis A". Am Fam Physician 73 (12): 2162–8. PMID 16848078. 
  19. ^ Lees D (2000). "Viruses and bivalve shellfish". Int. J. Food Microbiol. 59 (1-2): 81–116. doi:10.1016/S0168-1605(00)00248-8. PMID 10946842. http://linkinghub.elsevier.com/retrieve/pii/S0168-1605(00)00248-8. 
  20. ^ Hepatitis A Outbreak Associated with Green Onions at a Restaurant - Monaca, Pennsylvania, 2003

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