Hepatitis B

Definition

Hepatitis B is a liver disease caused by the hepatitis B virus (HBV).

Description

Hepatitis B is a form of viral hepatitis that is also known as serum hepatitis, due to its ability to be spread through body fluids and blood. HBV can cause lifelong infection, cirrhosis (scarring) of the liver, liver cancer , liver failure, and death. Hepatitis B is a more severe liver disease than hepatitis A , and asymptomatic infections occur frequently. Chronic hepatitis B infection may take one of two forms: chronic persistent hepatitis, a condition characterized by persistence of the virus but in which liver damage is minimal; and chronic active hepatitis, in which there is aggressive destruction of liver tissue and rapid progression to cirrhosis or liver failure.

Transmission

Transmission of HBV occurs through blood and body fluid exposure such as blood, semen, vaginal secretions, or saliva. Hepatitis B is not spread through food or water or by casual contact. Infants may also develop the disease if they are born to a mother who has the virus. Infected children often spread the virus to other children if there is frequent contact or a child has many scrapes or cuts. The common modes of transmission of hepatitis B are as follows:

children born to mothers who have hepatitis B (the illness may present up to five years after the child is born)
children who are born to mothers who have emigrated from a country where hepatitis B is widespread such as southeast Asia and China
individuals who live in households where another member is infected with the virus
infection through intravenous (IV) drug use and/or unprotected heterosexual or homosexual sexual contact
infection through blood transfusions from infected donors

Demographics

Worldwide there are 450 million carriers of hepatitis B, 50 million of which are in Africa. Carriage rates vary markedly in different areas. In South Africa, infection is much more common in rural communities than in the cities.

According to the Centers for Disease Control (CDC), an estimated 78,000 persons in the United States were infected with HBV in 2001. People of all ages get hepatitis B, and about 5,000 die per year of sickness caused by HBV. An estimated 1.25 million Americans are chronically infected, of whom 20 to 30 percent acquired their infection in childhood. It is estimated that hepatitis B accounts for 20 to 25 percent of all acute viral hepatitis in children. Infected newborns rarely suffer but have 90 percent chance of becoming carriers. Twenty-five percent of all HAV positive newborns develop chronic liver disease by the third to fourth decade of life.

Causes and symptoms

Hepatitis B is caused by HBV, also called Hepadna virus. The virus has an incubation period of two to five months. It replicates in the liver, and virus particles are shed in large amounts into the blood. The blood of infected individuals is thus highly infectious.

Hepatitis B has a wide range of symptoms. It can also be mild, without symptoms. When present, the symptoms are non-specific and usually include fever , tiredness, loss of appetite, nausea , abdominal discomfort, dark urine, clay-colored bowel movements, and jaundice (yellowing of the skin and eyes).

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 skin becomes much more 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.

Hepatitis B virus (HBV) is composed of an inner protein core and an outer protein capsule. The outer capsule contains the hepatitis B surface antigen (HBsAg). The inner core contains HBV core antigen (HBcAg) and hepatitis B e-antigen (HBeAg). This cell also contains polymerase, which catalyzes the formation of the cell's DNA. HBV is the only hepatitis-causing virus that has DNA, instead of RNA.

(Illustration by Electronic Illustrators Group.)

Diagnosis

A blood test is required to diagnose hepatitis B. The test detects one of the viral antigens called hepatitis B surface antigen (HBsAg) in the blood. Later on, HBsAg may no longer be present, in which case a test for antibodies to a different antigen, called hepatitis B core antigen, is used. If HBsAg can be detected in the blood for longer than six months, chronic hepatitis B is diagnosed.

Treatment

There is no cure for hepatitis B and no specific treatment is available. However, the following guidelines are often recommended:

Fluids and diet. The best treatment is to ensure 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. There is no medicine that gets rid of HBV or heals the liver. There are medications available to treat chronic HBV-infection. These work for some people, but experience with children is limited. Three drugs are licensed, as of 2004, for the treatment of chronic hepatitis B: Adefovir dipivoxil, alpha interferon, and lamivudine.

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 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 1–2 grams of protein per pound (2–3 grams per kilogram) of body weight. Children with cirrhosis need an individual nutrition plan from their pediatric specialist or nutritionist.

There is some evidence that iron can lower the response to interferon treatment in adults. Although no results have been reported for children, the issue of restricting iron intake should be discussed with the treating physician.

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 on in life. However, some children do have subsequent liver problems. Thus, it is important to keep in close touch with the treating physician and to keep all follow-up appointments. Chronic, or relapsing, infection occurs with hepatitis B in about 5–10 percent of cases.

Prevention

A vaccine for hepatitis B is as of 2004 widely used in the United States for routine childhood immunization. Children usually receive the first vaccine between birth and two months of age, the second vaccine at one to four months, and the third vaccine at six to 18 months. The vaccine is generally required for all children born on or after January 1, 1992, before they enter school. The vaccine is available for older children who may have not been immunized before 1992 and is recommended before age 11 or 12.

Parental concerns

If mothers have HBV in their blood, they can give hepatitis B to their baby during childbirth . Babies who get HBV at birth may have the virus for the rest of their lives, can spread the disease, and can get cirrhosis of the liver or liver cancer. The CDC recommends that all pregnant women be tested for HBV early in their pregnancy. If the blood test is positive, the baby should receive vaccine along with hepatitis B immune globulin (HBIG) at birth. The second dose of vaccine should be given at one to two months of age and the third dose at six months of age.

KEY TERMS

Cirrhosis —A chronic degenerative disease of the liver, in which normal cells are replaced by fibrous tissue and normal liver function is disrupted. The most common symptoms are mild jaundice, fluid collection in the tissues, mental confusion, and vomiting of blood. Cirrhosis is associated with portal hypertension and is a major risk factor for the later development of liver cancer. If left untreated, cirrhosis leads to liver failure.

Hepatitis B virus (HBV) —Also called Hepadna virus, the pathogen responsible for hepatitis B infection.

Jaundice —A condition in which the skin and whites of the eyes take on a yellowish color due to an increase of bilirubin (a compound produced by the liver) in the blood. Also called icterus.

Vaccine —A substance prepared from a weakened or killed microorganism which, when injected, helps the body to form antibodies that will prevent infection by the natural microorganism.

See also Hepatitis A ; Hepatitis B vaccine ; 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.

Blumberg, Baruch S. Hepatitis B: The Hunt for a Killer Virus . Princeton, NJ: Princeton University Press, 2002.

Everson, Gregory T., et al. Living with Hepatitis B: A Survivor's Guide. Long Island City, NY: Hatherleigh Press, 2004.

Green, William F., and H. Conjeevaram. The First Year—Hepatitis B: An Essential Guide for the Newly Diagnosed. New York: Marlowe & Co., 2002.

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.

Helvaci, M., et al. "Efficacy of hepatitis B vaccination and interferon-[alpha]-2b combination therapy versus interferon-[alpha]-2b monotherapy in children with chronic hepatitis B." Journal of Gastroenterology & Hepatology 19, no. 7 (July 2004): 785–91.

Liberek, A., et al. "Tolerance of interferon-alpha therapy in children with chronic hepatitis B." Journal of Paediatrics & Child Health 63, no. 23 (2003): 2625–49.

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.

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

Sokal, Etienne. "Drug Treatment of Pediatric Chronic Hepatitis B." Pediatric Drugs 4, no. 6 (2002): 361–69.

ORGANIZATIONS

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

Hepatitis B Foundation. 700 East Butler Avenue, Doylestown, PA 18901–2697. Web site: http://www.hepb.org.

Hepatitis Foundation International (HFI). 504 Blick Drive, Silver Spring, MD 20904–2901. Web site: http://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: http://www.cdc.gov/ncidod.

WEB SITES

"Viral Hepatitis B Homepage." NCID. Available online at http://www.cdc.gov/ncidod/diseases/hepatitis/b/index.htm (accessed October 22, 2004).

"What I need to know about Hepatitis B Homepage." NIHNDDIC . Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/hepb_e/ (accessed October 22, 2004).

Monique Laberge, Ph.D.