Disease
Hepatitis A

Author
Anastasia Lyudkevich, Biol 230, Spring 2009

Causative Agents
The Hepatitis A viruses are non-enveloped, single- stranded RNA viruses containing an icosahedral (def) capsid. This is a Hepatovirus belonging to the Picornaviridae family. These viruses are 28 nanometer (def) in diameter. The Hepatitis A virus infects humans, can with stand temperatures up to 60°C and can survive in fresh or salt water for months.

Epidemiology
Hepatitis A infections may be contracted by anyone, although some factors may put an individual at a greater risk for contraction; living in or traveling to areas such as the Western United States, Central and South America, Western Pacific, Africa, Asia and Middle Eastern countries will put an individual at a greater risk for contraction as these areas have an increased rate of the virus due to low standards of sanitation. Approximately 24 percent of all infected individuals have acquired the infection through living in the same household with already infected individuals. Homosexual activity that may promote fecal-oral spread of the virus is responsible for approximately 11 percent of infections.

The U.S. rate of Hepatitis A infections has declined by 76 percent in 2003. Infections in children age, 2–9 years were 89 percent lower and in states where vaccination is available and recommended the rates dropped 95 percent.

Transmission
Hepatitis A Viruses are transmitted to the enteric (def) via fecal-oral route or by contact with infected blood. Food borne transmission may also occur if an individual infected with the Hepatitis A virus contaminates food during harvesting or preparation. Prenatal (def) transmission may occur if the virus in the infected mother is in the viremia (def) phase which typically lasts 7 days.

After transmission of the Hepatitis A virus via fecal-oral route the virus enters the bloodstream by diffusing through the epithelium of the oropharynx (def) or intestine. The virus spreads through viremia to the liver where it replicates within its host cells; hepatocytes (def) and Kupffer cells (def). The Hepatitis A virions (def) are then secreted by the liver into bile (def) and released from the body by defecation in stools.

Signs and Symptoms
Although not everyone infected with the Hepatitis A virus will exhibit symptoms, some of the infections may be accompanied by severe to mild symptoms. Symptoms in adults are more severe than in children and include fatigue, nausea, fever, reduced appetite, darks-colored (orange to dark-brown) urine, abdominal pain and jaundice (def).  Jaundice is less likely to occur in infants and young children of age 5 or younger which express symptoms milder than adults.  Individuals infected with the Hepatitis A virus recover within a few weeks and the disease is rarely fatal although occasional fulminant (def) hepatitis death can occur mostly in individuals who are infected after age 50.  

Prevention and treatment
Acknowledging that the Hepatitis A virus is spread via fecal-oral rout, hygiene is an important step in preventing the contraction of the virus. Immunization (def) may be achieved through vaccination (def). The vaccine for the virus is the Havrix, Vaqta vaccine and may be administered by a doctor or nurse. The vaccine contains a false form of the Hepatitis A virus which signals the body to make antibodies (def) and respond with active immunity (def).

As of 2009 there are no treatments for the Hepatitis A virus although therapy is available. Nutritional therapy is a key in a successful recovery. A high-calorie and protein-rich diet is recommended. Alcoholic beverages should be avoided while infected with the virus because of the hepatotoxic (def) effect of alcohol on the liver. Slow down but do not stop; minimizing activity to the level of your moderate capacity, staying in bed will slow the recovery process.

Bibliography

Hepatitis A Vaccine. Www.webmd.com. 2005. Wed MD. 6 Apr. 2009. http://www.webmd.com/hepatitis/hepatitis-a-vaccine.

Hepatitis A (Infectious Hepatitis). Www.health.state.ny.us. Dec. 2008. New York State Department of Health. 6 Apr. 2009.                                                                                                                                             http://www.health.state.ny.us/diseases/communicable/hepatitis/hepatitis_a/fact_sheet.htm.

Hepatitis A Transmission. Www.hepatitis.emedtv.com. 2006. Med TV. 6 Apr. 2009
http://hepatitis.emedtv.com/hepatitis-a/hepatitis-a-transmission.html.

Hepatitis A. Www.wikipedia.org. 2009. Free Encyclopedia. 6 Apr. 2009
http://en.wikipedia.org/wiki/Hepatitis_a_virus.

Hunt, Richard. Hepatitis Viruses. Www.pathmicro.med.sc.edu. 2004. University of South Carolina. 6 Apr. 2009
http://pathmicro.med.sc.edu/virol/hepatitis-virus.htm.

Zuger, Abigail. Epidemiology of Hepatitis A Transformed by Vaccine. Www.general-medicine. jwatch.org. 13 July 2005. Journal Watch Medicine That Matters. 6 Apr. 2009                                                     http://general-medicine.jwatch.org/cgi/content/full/2005/819/1.