Hepatitis A and Hepatitis B
Symptoms and Causative Agent
Hepatitis is a general term for inflammation of the liver, which may result from infectious or non-infectious causes. Viruses responsible for many cases of infectious hepatitis include hepatitis A, hepatitis B, hepatitis C, hepatitis D, and hepatitis E. Hepatitis A and B are the only hepatitis viruses for which vaccines are currently available (although immunity for hepatitis B also confers immunity for hepatitis D--sometimes known as delta hepatitis).
The hepatitis B virus (HBV) is a partly double-stranded DNA virus in the hepadnavirus family. The hepatitis A virus (HAV) is a single-stranded RNA virus in the picornavirus family. Both viruses, though they are structurally unrelated to one another, infect and replicate primarily in liver cells.
The symptoms of acute hepatitis A infection are identical to those of hepatitis B infection. Early symptoms are headache, nausea, vomiting, abdominal pain, fever, rash, body aches and pains, and dark colored urine. Following this phase, jaundice (yellow-colored skin and whites of the eyes), light stools, and liver pain may appear.
The hepatitis B virus is spread via contact with infectious body fluids (namely, blood, saliva, and semen). It can be spread sexually, or through sharing of injection drug use equipment, needle sticks, birth to an infected mother, contact with open sores or wounds of an infected person, and sharing of razors or toothbrushes with an infected person. While saliva can serve as a means of transmission in bites, it is not likely that kissing is a viable means of transmitting the virus.
The fecal-oral route is the main transmission pathway for the hepatitis A virus. This may occur through person-to-person contact or by eating or drinking contaminated food or water. HAV is not known to be spread via saliva. In very rare cases it has been spread via contaminated blood transfusions.
Both viruses are extremely hardy and can remain infectious on surfaces for more than seven days at room temperature, although this is unlikely to account for infection transmission in most cases.
Treatment and Care
No specific treatments exist for acute hepatitis A and B infections. Rather, they are treated with supportive care, such as rest, fluid management, and pain and fever relief.
See below for a discussion of treatment for chronic hepatitis B infection.
Complications and Mortality Rate
Both hepatitis A and hepatitis B infection can have immediate, deadly consequences. Approximately 1% of people with acute HBV infections will suffer fulminant hepatitis, or acute liver failure. HAV infection may also, though less commonly than HBV infection, lead to fulminant hepatitis. Up to 90% of patients with fulminant hepatitis will die.
Up to 95% of adults infected with acute HBV infection recover and do not become chronically (permanently) infected, although they can infect other people during the acute phase via transmission of body secretions. The others become chronically infected—and able to infect others for a much longer time (in some cases for many years)—and are at risk for serious liver disease. The picture is different for children: infants and children who become infected with hepatitis B are much more likely than adults to become chronically infected and hence to develop serious, late complications.
Chronic infection with HBV may lead to cirrhosis, liver failure, and liver cancer. HAV infection does not lead to chronic infection or chronic liver disease.
Treatment for patients with chronic HBV infection may include interferon therapy, which reduces or eliminates the virus in some patients. Interferon blocks viral replication and enhances the body’s immune response to infected cells. Because interferon is an injectable medicine and has some potentially serious side effects, some patients may be advised to delay or avoid interferon treatment or to use one of the several oral medicines such as lamivudine, adefovir or entecavir. Treatment is always administered and monitored by a clinician familiar with viral hepatitis.
Available Vaccines and Vaccination Campaigns
Hepatitis B Vaccines
The FDA has licensed several hepatitis B vaccines for use in the United States, including several combination vaccines. It has been part of the routine childhood immunization schedule since 1994. Some parents object to vaccinating their newborns against a disease they mistakenly think is spread only via sexual contact and IV drug use. However, newborns and young children are at risk for hepatitis B infection: apart from maternal transmission of hepatitis B to a newborn, hepatitis B transmission has been reported in school and daycare settings among children. The vaccine contains no live virus and is safe even for people with reduced immune function.
Following are the general recommendation for hepatitis B vaccination:
Hepatitis B vaccination is recommended for all children, starting at birth in a three-dose series spread over many months. Additionally, all children and adolescents under age 19 who have not been vaccinated are recommended to receive the vaccine, as are adult populations at risk of HBV infection.
Hepatitis A Vaccines
Several vaccines for hepatitis A are available in the United States, including several combination vaccines. It has been part of the routine childhood immunization schedule since 1994. Hepatitis vaccination is recommended at age 1, with a booster shot several months later. For those people who have not had hepatitis A and have not already been vaccinated, travel to developing countries can be a trigger for pre-departure hepatitis A vaccine. It is important to allow at least two weeks before departure for vaccination. The benefits of a single administration of vaccine should last for several months, but getting a second dose will confer much longer term immunity. The vaccine contains no live virus and is safe even for people with reduced immune function.
Following are the general recommendations for hepatitis A vaccination:
Hepatitis A vaccination is recommended for all children at age 1 year, for persons who are at increased risk for infection, for persons who are at increased risk for complications from hepatitis A, and for any person wishing to obtain immunity.
Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases. Atkinson W, Wolfe S, Hamborsky J, eds. 12th ed. Washington DC: Public Health Foundation, 2011.http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/hepa.pdf Accessed July 20, 2011.
Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases. Atkinson W, Wolfe S, Hamborsky J, eds. 12th ed. Washington DC: Public Health Foundation, 2011. http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/hepb.pdf Accessed July 20, 2011.
Feigin RD, Cherry JD, Demmler GJ, Kaplan SL. Texbook of Pediatric Infectious Diseases, 5th ed., vol 2. Philadelphia: Saunders, 2004.
Immunization Action Coalition. Unusual cases of hepatitis B virus transmission. http://www.immunize.org/catg.d/p2100nrs.pdf Accessed August 2, 2011.
Plotkin SA, Orenstein WA, Offit PA. Vaccines, 5th ed. Philadelphia: Saunders, 2005.
Timeline Entry: 1981 Hepatitis B: First Subunit Viral Vaccine in U.S.
The FDA licensed Hilleman’s human-blood-derived hepatitis B vaccine, Heptavax-B. It was the first subunit viral vaccine developed in the United States.
Hilleman transformed the hepatitis B surface protein, discovered by Baruch Blumberg and known as the Australia antigen, into an effective vaccine. Hilleman harvested serum from several IV drug users and homosexual men, in whom the disease was sometimes present, to obtain the antigen. He used three methods to purify the blood so that the infectious particles were assuredly killed, but the antigen remained.
The vaccine proved effective at preventing hepatitis B. But, because of concerns about HIV infection, it was superseded in 1986 by a product that did not use human serum. This new effort produced the first vaccine based on recombinant technology--in this case, changing yeast cells so that they produced the protein that is the active ingredient in the current hepatitis B vaccine.See This Item In The Timeline
Timeline Entry: 5/19/2006 Hepatitis A: Vaccine Recommended for All Children
The Advisory Committee on Immunization Practices (ACIP) recommended routine hepatitis A vaccination of all children older than age 1 in a two-dose schedule.
The U.S. Food and Drug Administration had licensed several inactivated hepatitis A vaccines in 1995 and 1996. After that, vaccination for children was gradually phased in, beginning with children in communities with the highest rates of the disease. Next, in 1999, ACIP recommended routine vaccination for children living in areas with elevated rates of the disease. Finally, in 2006, ACIP widened the recommendations to include all children older than age 1.
Between 1980 and 1995, 22,000-36,000 cases of hepatitis A were reported annually in the United States. The actual number of infections was likely closer to 271,000 infections per year (reported cases are often just a fraction of actual cases). After widespread immunization practices, in 2007 there were just 2,979 reported cases of hepatitis A in the United States.See This Item In The Timeline