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Hepatitis
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Accession Number
A00276
Author
National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID)
Source
NIAID Fact Sheet
Release Date
August 1, 1992
Major Descriptors
Antigens
Hepatitis
Prevention
Transmission
Treatment
National Institute of Allergies and Infectious Disease (NIAID)
Topic
Hepatitis
Text
Hepatitis is an inflammation of the liver caused by certain viruses and other factors, such as alcohol abuse, some medications, and trauma. Its various forms affect millions of Americans. Although many cases of hepatitis are not a serious threat to health, the disease can become chronic (long-lasting) and can sometimes lead to liver failure and death.
CAUSE
There are four major types of viral hepatitis:
* Hepatitis A, caused by infection with the hepatitis A virus, is usually a mild disease that does not become chronic. The virus is sometimes passed on through sexual practices involving oral-anal contact. It is most commonly spread by food and water contamination.
* Hepatitis B, caused by infection with the hepatitis B virus (HBV), may be mild or severe, acute or chronic. HBV is most commonly passed on to a sexual partner during intercourse, especially during anal sex. Because the disease is not easily spread, persons with HBV should not worry about spreading it through casual contact such as shaking hands or sharing a workspace or bathroom facility.
Each year, an estimated 300,000 persons in the United States become infected with HBV. Hepatitis B is most commonly transmitted by sharing drug needles, by engaging in high-risk sexual behavior, from a mother to her newborn, and in the health care setting.
* Non-A, non-B hepatitis is primarily caused by the hepatitis C virus (HCV). Although generally a mild condition, it is much more likely than hepatitis B to lead to chronic liver disease. HCV appears to be spread through sexual contact as well as through sharing drug needles. Sexual spread, however, is inefficient and much less than that for HBV or the AIDS virus (HIV). With the advent of new tests to screen blood donors, a very small percentage of persons with HCV currently become infected through blood transfusions.
The hepatitis E virus causes another type of non-A, non-B hepatitis. This virus is principally spread through contaminated water in areas with poor sanitation. This form of hepatitis does not occur if the U.S. and is not known to be passed on through sexual contact.
* Delta hepatitis occurs only in people who already are infected with HBV. A potentially severe disease, it is caused by a virus (HDV) that can produce disease only when HBV is also present. Most cases occur among people who are frequently exposed to blood and blood products, such as people with hemophilia. Small-scale epidemics have occurred among injection drug users who share contaminated needles.
Experts believe that HDV may be sexually transmitted, but further research is needed to provide more specific evidence.
TRANSMISSION
HBV, HCV, and HDV can be spread in the following ways:
* Having sexual intercourse with an infected person without using a condom.
* Sharing drug needles among users of injected street drugs.
* Needle-stick accidents among health-care workers.
* Mother-to-child transmission of HBV during birth.
* Transfusions. Until recently, blood transfusions were the most frequent cause of hepatitis C. Blood banks in the United States now screen donated blood for HBV and HCV and discard any blood that appears to be infected. Therefore, the risk of acquiring hepatitis from these viruses is very low in the U.S. and in other countries where blood is similarly tested. Tests to screen blood for HBV will also screen out HDV.
* Personal contact with an infected person. HBV, HCV, and HDV sometimes spread when household members unknowingly come in contact with virus-infected blood or body fluids -- most probably through cuts and scrapes or by sharing personal items such as razors and toothbrushes. While it is possible to become infected by contact with saliva, blood and semen remain the major sources of infection.
SYMPTOMS
Many people infected with viral hepatitis have no symptoms. For example, about one-third of people infected with HBV have a completely "silent" disease. When symptoms are present, they may be mild or severe. The most common early symptoms are mild fever, headache, muscle aches, fatigue, loss of appetite, nausea, vomiting, or diarrhea. Later symptoms may include dark and foamy urine and pale feces; abdominal pain; and yellowing of the skin and whites of the eyes (jaundice).
About 15 to 20 percent of patients develop short-term arthritis-like problems as part of a more severe case of hepatitis B. Another one-third of those with hepatitis B develop only mild flu-like symptoms without jaundice. Very severe (fulminant) hepatitis B is rare, but life-threatening. Early signs of fulminant hepatitis, such as personality changes and agitated behavior, require immediate medical attention.
Some people infected with HBV or HCV become chronic carriers of the virus, although they may have no symptoms. There are an estimated 1.5 million HBV carriers in the U.S. and 300 million carriers worldwide. Children are at greatest risk. About 90 percent of babies who become infected at birth with HBV, and up to half of youngsters who are infected before age 5, become chronic carriers. It is estimated that there are between 2 and 5 million HCV chronic carriers. At least half of all HCV carriers will develop chronic liver disease, regardless of whether or not they have symptoms.
DIAGNOSIS
Hepatitis B. Several types of blood tests can detect signs of HBV even before symptoms develop. These tests measure liver function and identify HBV antigens (proteins of the virus) or antibodies (proteins produced by the body in response to the virus) in the blood. Tests for hepatitis B include:
* Hepatitis B Surface Antigen (HBsAg). Most people with acute hepatitis B have HBsAg in their blood before symptoms develop. As a person recovers from the illness, HBsAg disappears. If it is still present 6 months after infection, it may indicate that a person has developed chronic hepatitis or may be a symptomless carrier of the virus. HBsAg can be detected by a number of laboratory tests such as radioimmunoassay or enzyme-linked immunosorbent assay (ELISA). Antibody to the surface antigen (anti-HBs) persists for many years. This antibody usually appears as the acute illness improves, providing protection against future HBV infections.
* Hepatitis B Core Antigen (HBcAg). The HBV core protein can be identified only after the surface antigen has been stripped away using special techniques. Commercially available blood tests cannot detect HbcAg in blood, but antibody to the core antigen (anti-HBc) can be detected during acute illness. High levels of anti-HBc are present at the start of illness, and they gradually decrease over time in most people. In contrast, chronic carriers of HBV have high levels of anti-HBc in their blood that may persist throughout life.
* E Antigen (HBeAg). The presence of e antigen indicates that a person infected with HBV is highly infectious. An HBsAg-positive pregnant woman whose blood contains e antigen is likely to transmit the virus to her newborn. By contrast, antibody to the e antigen (anti-HBe) may point to a lower degree of infectivity and a reduced likelihood of becoming a carrier. Laboratory blood tests can detect e antigen as well as anti-HBe.
* Liver Function Tests. A number of blood tests can be performed to determine how well a person's liver is functioning, and these results can aid in diagnosing hepatitis B infection. High levels of the liver enzymes aspartate transferase (AST) and alanine transferase (ALT) are of particular importance. (These were formerly called SGOT and SGPT.)
Delta hepatitis. Until recently, delta hepatitis could be diagnosed only by liver biopsy in which a tiny piece of the liver is removed and examined. Scientists supported by the NIAID have developed a procedure to detect part of the genetic material of the virus in a patient's blood, which will allow easier, faster diagnosis. A blood test is also now available to detect antibody to delta antigen (a protein found inside the delta hepatitis virus).
Hepatitis C. A new test is now available to detect hepatitis C. The test identifies antibody to HCV, which is present in more than 50 percent of persons with acute hepatitis C and in almost all with chronic hepatitis.
TREATMENT
At present, there are no specific treatments for the acute symptoms of viral hepatitis. Doctors recommend bed rest, a healthy diet, and avoidance of alcoholic beverages.
A genetically engineered form of a naturally occurring protein, interferon alpha, is used to treat people with chronic hepatitis C. NIH-supported studies led to the approval of interferon alpha for the treatment of those with chronic HBV as well. The drug improves liver function in some people with hepatitis and diminishes symptoms, although it may cause side effects such as headache, fever, and other flu-like symptoms. Some patients do not respond to interferon alpha, and in others its beneficial effects lessen over time. Scientists are evaluating a number of experimental therapies that may be more effective and less toxic.
POSSIBLE COMPLICATIONS
Most patients with mild to severe acute hepatitis begin to feel better in 2 to 3 weeks and recover completely within 4 to 8 weeks. People with acute HBV infection who develop an HCV infection at the same time may be at particular risk for developing severe, life-threatening acute hepatitis. Many chronic carriers remain symptom free or develop only a mild condition, chronic persistent hepatitis. However, a small percentage go on to develop the most serious complications of viral hepatitis: cirrhosis of the liver, liver cancer, and immune system disorders. Chronic carriers of HBV who become infected with HDV may develop severe acute hepatitis. They also have a high risk of becoming carriers of HDV.
PREVENTION
The most effective means of preventing viral hepatitis is to avoid contact with the blood, saliva, semen, or vaginal secretions of infected individuals. People who have acute or chronic viral hepatitis should:
* Avoid sharing items that could infect others, such as razors or toothbrushes.
* Protect sex partners from exposure to their semen, vaginal fluids, or blood. Properly used condoms may be effective in preventing sexual transmission.
There are several vaccines available to prevent hepatitis B. People at high risk of infection should consider vaccination: male homosexuals and heterosexuals with multiple partners, people who receive hemodialysis or blood products, household and sexual contacts of HBV carriers, and users of intravenous street drugs who share needles. Regulations now require health care and laboratory workers who handle blood and other body fluids to be vaccinated. People who have come into direct contact with the blood or body fluids of an HBV carrier may receive one or more injections of hepatitis B immune globulin, sometimes in combination with hepatitis B vaccine. Immune globulin offers temporary protection, while the vaccine provides a longer-lasting immunity.
In an effort to eliminate chronic carriers, the U.S. Centers for Disease Control recommends that all newborn babies be vaccinated. Other groups have recommended that pregnant women be screened for HBsAg as part of their routine prenatal care. If they are infected, their babies can be given hepatitis B immune globulin as well as vaccine immediately after birth.
No vaccines yet exist for HCV or HDV; however, HBV vaccine will prevent delta hepatitis as well.
RESEARCH
NIAID supported scientists are attacking hepatitis infection from several fronts. Work is under way to evaluate the potential of antiviral drugs to treat people already infected with HBV, HCV, and HDV. Vaccines and drugs are being tested in the woodchuck, an animal that develops a disease similar to HBV infection in humans. This animal also can be a chronic carrier of HDV, making it a valuable model for studying these viruses and helping scientists understand hepatitis infection.
In addition to testing their effectiveness, scientists are studying how to make antiviral drugs less toxic and how to deliver them to their appropriate targets in the body.
By studying the immune response to hepatitis viruses, scientists hope to identify the precise mechanisms that lead to either recovery or chronic disease. Knowledge is being gained from studies with transgenic mice (mice that carry human genes for HBV). By modifying viral genes and inoculating pregnant women, it may be possible to boost the immune response of babies to HBV. This approach could reduce a large number of chronic carriers and stem the spread of the disease to future generations.
For further information, contact:
American Liver Foundation 998 Pompton Avenue Cedar Grove, NJ 07009 (800) 223-0179
Hepatitis Foundation International 30 Sunrise Terrace Cedar Grove, NJ 07009 (800) 891-0707 or (201) 239-1035
National Digestive Diseases Clearinghouse Box NDDIC Bethesda, MD 20892 (301) 496-3583
Prepared by: Office of Communications National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda, MD 20892
Public Health Service U.S. Department of Health and Human Services
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