Hepatitis B virus (HBV) is a double-stranded deoxyribonucleic acid (DNA) virus. HBV is transmitted by three main mechanisms: (1) percutaneous inoculation (such as by sharing of contaminated needles, accidental needlesticks, or contacting a contaminated blood mucous membrane, or passing through a skin break); (2) intimate contact (especially sexual); and (3) perinatal spread from an infected mother to her newborn infant. Hepatitis B surface antigen (HBsAg) has been isolated in all body fluids. Blood and blood products, saliva, semen, and vaginal fluids are infectious.
Since November 1981, a vaccine for hepatitis B has been available in the United States. Despite the availability of a vaccine, the reported incidence of hepatitis B increased by 37 percent from 1979 to 1989. The majority of these new cases occurred among injection drug users and heterosexuals with multiple partners. Since 1989, the reported incidence of hepatitis B has declined about 40 percent. Only 25 percent of the new cases of HBV infection in the United States each year have acute icteric disease (jaundice). The fact that the majority of cases of HBV infection are subclinical contributes to the spread of this virus.
The incidence of HBV infection is increasing. About 200 million people worldwide are carriers of HBV. In the United States, most new cases of HBV infection occur among young adults. The Centers for Disease Control and Prevention (CDC) estimates that there are 200,000 to 300,000 new cases of HBV a year and that about 1.5 million people in the United States are infected. HBV infection is higher in certain at-risk populations in which 5 to 20 percent of persons are HBsAg positive, than in the general U.S. population. The incidence is highest in drug users, heterosexuals with multiple sexual partners, men who have sex with other men, persons in certain health care occupations, and persons born outside the United States in areas where HBV is endemic. The highest serologic evidence for prior HBV infection is in the following categories:
High risk - immigrants from Southeast Asia, China, and Africa; clients in residential institutions for the developmentally disabled; injection drug users; men who have sex with other men; household contacts of HBV carriers; hemodialysis patients; and persons with multiple heterosexual partners
Intermediate risk - prisoners (male), staff workers in institutions for the mentally retarded, and health care workers with frequent blood contact
Hepatitis B is spread primarily by the HBV chronic carrier. In the United States, there are an estimated 1 to 1.5 million persons with chronic HBV infection who are potentially infectious to others. Hepatitis B infection may also be spread by persons with the acute disease, since persons with acute hepatitis B may be infectious but asymptomatic.
After the initial exposure, the incubation period averages 60 to 90 days, with a range of 6 weeks to 6 months; infected persons may be infectious to others before the onset of symptoms. With acute icteric hepatitis, the onset of symptoms is gradual and includes loss of appetite, vague abdominal discomfort, weight loss, fever, nausea, vomiting, and diarrhea; dark tea-colored urine; and muscle aches and skin rash, which may occur prior to the development of clinical jaundice. In the majority of cases of HBV disease, however, the infection is self-limited, with no evident jaundice. For this reason, most persons do not know that they are infected. Subclinical infection may occur with no symptoms.
Approximately 10 percent of infected persons go on to develop chronic hepatitis, and 25 percent of this group may develop cirrhosis or hepatocellular carcinoma at some time.
The prevalence of HBV infection among injection drug users in the United States ranges from 60 to 80 percent, depending on the region. Because of this high prevalence, all persons enrolled in drug treatment programs and all clinical staff should be screened for prior HBV infection. Screening for HBV infection in methadone treatment programs is required by some States but is not mandated in the Federal regulations. Such screening is considered good medical practice, and should be accompanied by appropriate counseling, vaccination, and needed medical followup. Screening for HBV in these high- risk groups has been shown to be cost-effective.
In setting up a screening and treatment or referral program, the following medical issues and components need to be included:
Screening and vaccination, if appropriate, need to be a routine part of care in methadone treatment programs. If there is no serologic evidence of prior HBV infection, hepatitis B vaccine should be administered.
At-risk, previously unexposed persons must be vaccinated; if at-risk persons are not vaccinated, they should be rescreened every 6 to 12 months.
After a known exposure to HBV, an at-risk person should be given the hepatitis B vaccine as well as hepatitis B immune globulin (HBIG) in a timely fashion.
Periodic serologic screening for HBV and appropriate followup should be an ongoing concern in methadone treatment programs.
The risk of occupational exposure to bloodborne pathogens, including HIV and HBV, exists for employees who can be reasonably anticipated to have contact with blood or other potentially infectious material while performing their duties. Any health care worker at such risk must be offered the hepatitis B vaccination unless the employee has previously received the complete hepatitis B vaccination series, antibody testing has shown the employee is immune, or the vaccine is contraindicated for medical reasons. If the employee refuses the hepatitis B vaccination series, the employee must sign an Occupational Safety and Health Administration (OSHA) vaccination declination form.
Methadone and other drug treatment programs need to be aware of the following issues with regard to those patients infected with hepatitis B:
Certain prescribed drugs may be contraindicated for persons with ongoing liver disease secondary to HBV infection. These drugs include methadone, isoniazid (INH), rifampin, oral contraceptives, and antiseizure medications.
The use of a interferon to treat chronic active hepatitis B infection is a medical issue for those persons who are positive for hepatitis B surface antigen (HBsAg) and show evidence of chronic active hepatitis. For some infected persons, liver transplantation may be the appropriate therapeutic option.
Persons known to be HBsAg positive should be counseled regarding safer sex practices and notification of partners and household contacts. In addition, they should be advised not to share toothbrushes, drinking cups or glasses, razors, rubber gloves, towels, or drug paraphernalia. However, since HBV is not spread through food or drink, persons who are infected with HBV may handle food for others.
Those who care for infected infants or children should be counseled about not allowing the children to share their toys, baby bottles, or other such objects.
Clients who refuse HBV testing should not be excluded from a treatment program because of presumed or actual viral hepatitis. Admission to a drug treatment program should not be restricted unless illness precludes the patient's participation in the program and limits the patient's ability to carry on routine daily activities.
Patients in drug treatment programs need to be educated about relevant health issues and sexual practices, since this is a major means of preventing the spread of HBV and other infectious agents. The education should be ongoing and relevant to the issues of each treatment program. For further information, see "Issues for Counselors."
Staff should employ universal precautions when coming in contact with body fluids, regardless of the documented status of a person for potentially infectious bloodborne pathogens (including HIV and HBV). All blood and other body fluids containing visible blood should be considered potentially infectious. In addition, universal precautions should be applied to body tissues and to cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, and amniotic fluid.
With persons who have acute viral hepatitis, CDC guidelines for contact isolation should be followed. Patients and staff should observe good personal hygiene, especially hand washing. Staff who will be drawing blood should follow the guidelines listed in table 1. When disposing of infectious or potentially infectious waste, local and State regulations should be followed.
All States mandate that cases of clinical viral hepatitis be reported. Reporting of chronic carriers (HBsAg positive or hepatitis B core antibody positive with a negative hepatitis B surface antibody and antigen) should be done promptly in accordance with local and State health department regulations to facilitate contact tracing.
All methadone and other drug treatment programs should develop a resource list providing information on local, State, and CDC guidelines for screening and treatment of HBV, as well as for reporting of HBV-infected persons to health departments.
Methadone and other drug treatment facilities need to screen all patients, as well as at-risk staff members. Any health care worker whose tasks involve contact with blood or blood-contaminated body fluids should be screened. See table 2 for behavioral risk indicators and table 3 for medical indicators of active hepatitis.
In screening for acute hepatitis B, the two critical components are (1) the clinical findings and (2) the serological tests. For clinical findings (medical indicators for active hepatitis), see table 3. The serologic tests determine the presence of hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc) immunoglobulin M (IgM) and immunoglobulin G (IgG), and hepatitis B surface antibody (anti-HBs).
When screening for acute HBV infection, it must be remembered that acute HBV may present clinically the same as acute hepatitis A, acute hepatitis C, Epstein-Barr virus (infectious mononucleosis), and cytomegalovirus infection. In addition, hepatitis may be caused by certain drugs, such as isoniazid and phenytoin (Dilantin), as well as by alcohol and industrial chemicals (for example, benzene).
In screening for prior infection, the results of serologic tests are helpful in determining if the infection is acute or occurred in the recent or distant past and whether the patient is immune or infectious to others. The initial serologic tests measure hepatitis B surface antigen, hepatitis B core antibody, and hepatitis B surface antibody. All of these tests should be done as the initial screen to avoid the necessity of having the patient return for additional testing, as would be the case if only the IgG core antibody is done as the initial screening test and it turns out to be positive. Liver function tests should be drawn and sent to the laboratory at the same time as the initial screen. The presence of immunoglobulin M antibody to hepatitis B core antigen helps to identify recent infection in most cases. However, in patients with a flareup of chronic HBV infection, serum anti-HBc IgM may be present.
Test results may be interpreted as follows:
If HBsAg positive:
Obtain results of the liver function tests that measure aspartate aminotransferase (AST/SGOT) and alanine aminotransferase (ALT/SGPT); if transaminases are elevated, this is consistent with acute or chronic hepatitis B. In addition, however, other causes of hepatitis unrelated to HBV need to be excluded, such as viral hepatitis A, viral hepatitis C, alcoholic hepatitis, or drug-induced hepatitis, all of which may be present in someone who also has hepatitis B.
Obtain results of anti-HBc.
If anti-HBc IgM is positive, this represents recent, acute infection or a flareup of chronic HBV infection.
If anti-HBc IgM is negative but anti-HBc IgG is positive, this represents chronic hepatitis B infection in most people.
To identify a person as having chronic HBV infection, the HBsAg must have been positive for 6 months or longer. Therefore, some people may require repeat testing in 6 or more months.
If HBsAg is positive, most laboratories will then test that same serum sample for the hepatitis Be antigen (HBeAg), also called the Dane particle, and the hepatitis Be antibody (anti-HBe).
If HBeAg and HBsAg are both positive, this represents a high level of potential infectivity to other persons.
If HBsAg and anti-HBe are both positive, the patient is less infectious to others than if HBsAg and HBeAg are both positive.
Since the approach to counseling, therapy, or diagnosis does not differ for a patient who is highly infectious versus one who is less infectious, there is no need to test for the presence of HBeAg or anti-HBe if these tests are not routinely performed.
Do a complete history and physical examination.
If HBsAg negative:
Review the results of hepatitis B surface antibody and anti-HBc.
If anti-HBs is positive, this represents past infection with HBV. If anti-HBc IgM is positive, this represents a recent infection. If anti-HBc IgM is absent, infection occurred in the distant past regardless of the presence or absence of anti-HBc IgG.
The presence of both anti-HBs and anti-HBc - with both negative HBsAg and anti-HBc IgM - represents past infection with HBV and immunity.
With recent infection, anti-HBc IgM alone may be present at a high level after the disappearance of HBsAg and before the appearance of anti-HBs.
Anti-HBc alone may also represent past infection, and such a person is not infectious to others.
Anti-HBs alone is a marker of protective immunity for persons vaccinated against HBV.
The correlation of the serologic test results for HBV infection with the stage of disease is shown in table 4. If there are questions about the interpretation of the test results, these should be reviewed with a physician knowledgeable about viral hepatitis.
If the test results do not clearly establish the stage of infection, a second blood sample may need to be obtained after 1 or more months.
If the test results do not clearly explain the stage of HBV infection or if there is laboratory and/or clinical evidence of acute or chronic hepatitis of uncertain etiology, the patient should be referred out for further medical evaluation and followup.
Any patient with no serologic evidence of prior exposure, including a negative anti-HBs, should be offered hepatitis B vaccine. Any patient who is a healthy HBsAg carrier or who has chronic hepatitis B should be counseled about risk behavior for exposing other persons.
Recovery usually occurs in 4 to 6 weeks. Fulminant acute hepatitis with liver failure and encephalopathy is rare. Prolonged acute hepatitis with symptoms for more than 3 to 4 months occurs in 3 to 5 percent of cases. Relapsing hepatitis after the initial episode may occur one or more times.
Persistent HBV infection occurs in approximately 10 percent of persons infected with HBV. Persons with persistent HBV infection remain HBsAg positive. Overall, 70 percent have chronic persistent hepatitis and 30 percent have chronic active hepatitis with the following characteristics:
Chronic persistent hepatitis is usually asymptomatic, with persistent or recurrent elevation in AST and ALT, without jaundice and with mild hepatosplenomegaly.
Chronic active hepatitis (CAH) is characterized by intermittent or no episodes of jaundice. When jaundice occurs, transaminases (ALT and AST) are markedly elevated. The prognosis is variable, and many persons with CAH develop cirrhosis. Cirrhosis, hepatic failure, and premature death may occur. Persons with CAH should be under appropriate medical supervision.
The diagnosis of chronic active or chronic persistent hepatitis is based on certain characteristic findings on histopathologic examination of hepatitic tissue. To make these diagnoses, therefore, a liver biopsy is necessary.
Persons with chronic hepatitis who remain HBsAg positive for more than 6 months are said to be chronic carriers. Chronic carriers of HBV constitute a human reservoir of persistently infected persons responsible, in large part, for the ongoing spread of HBV.
Treatment of chronic active hepatitis with a interferon may be appropriate and effective. However, such treatment would have to be done with qualified medical supervision.
Cases of HBV infection are associated with the risk group behaviors outlined previously; vaccination programs should be directed at persons with known risk behavior. Injection drug users who are not already infected with HBV should be vaccinated as early as possible after their drug use begins. Vaccination and appropriate, timely post-exposure prophylaxis are of proven efficacy in preventing hepatitis B.
The currently available hepatitis B vaccines are produced by recombinant DNA technology. There is no risk of infection with any viral or other infectious agent. Currently licensed HB vaccines include Recombivax-HB (Merck, Sharpe and Dohme) and Engerix-B (SK Biologicals). For recommended dosages by population group, see table 5.
In addition, these guidelines should be followed in administering vaccine:
The vaccine is administered as a series of three intramuscular doses given in the deltoid muscle of adults and children. The second and third injections should be given at 1 and 6 months after the first dose. The Energix-B vaccine is also licensed to be given in four doses administered at 0, 1, 2, and 12 months.
Postvaccination testing for serologic response (anti-HBs) is advised for certain groups: persons with HIV infection and dialysis patients and staff, including both adults and children.
When the series is properly administered, there is a protective antibody response in more than 90 percent of healthy adults and in more than 95 percent of infants, children, and adolescents. Ensuring completion of the 3- to 4-series vaccine may be difficult with injection drug users and others at risk. A study of injection drug users showed that only 81 percent of them had received any HB vaccine. Among those who received any vaccine, 61 percent received only the initial dose, 24 percent received the first two doses, and only 15 percent received all three doses. In this study group, 19 percent received no vaccine; 86 percent of those receiving no vaccine were in correctional institutions or drug treatment centers - sites where recommended doses could have been administered.
The Centers for Disease Control and Prevention recommendations about how to proceed when the vaccination series has been interrupted are listed in table 6.
Any percutaneous exposure (needlestick, laceration, or human bite) or permucosal exposure (ocular or mucous membrane) to potentially HBV-infectious blood is of concern. To decide who requires prophylaxis, the following information is needed:
Is the source of the blood available?
What is the HBsAg status of the source?
What is the hepatitis B vaccination status and vaccine response of the exposed person?
Table 7 shows CDC recommendations for prophylaxis of sex partners and household contacts of persons with HBV infection.
Persons infected with HIV may have a suboptimal response to HB vaccine even if the vaccine is properly administered. For this reason, consideration should be given to administering the higher dose (see table 5) of HB vaccine to HIV-infected persons. This higher dose of HB vaccine is currently recommended for dialysis patients and immunocompromised patients; HIV-infected persons may also benefit from this increased dose of HB vaccine.
HIV-infected persons should be tested postvaccination for immunity. The anti-HBs level should be measured 1 to 6 months after completion of the vaccine series. For persons who do not respond to the primary vaccine series, one or more additional vaccine doses may provide protective immunity.
A person is considered to have protective immunity against HBV if that person has a concentration of anti-HBs of at least 10 mIU/mL by radioimmunoassay. There is concern that, over time, the protective immunity may diminish. For an HIV-infected person who did not respond appropriately to the initial vaccine series and was, therefore, given one or more additional vaccine doses, there are currently no CDC recommendations for testing that person to demonstrate protective immunity or for administering additional vaccine.
A woman who has active hepatitis should be advised not to become pregnant. HBsAg-positive women should be evaluated for HBV-related liver disease as described in the screening guidelines.
All pregnant women should be tested for HBsAg early in pregnancy. If the woman is at high risk for HBV infection, the HBsAg test should be repeated late in pregnancy, even if the woman was initially HBsAg negative. High-risk women would include injection drug users, those with other sexually transmitted diseases during the pregnancy, those with multiple sexual partners during the pregnancy, and those with clinically evident hepatitis.
Pregnant women with known risk behavior should be vaccinated, since hepatitis B vaccine may be given safely to pregnant and lactating and/or breastfeeding women. If the pregnant woman is HBsAg positive, the general guidelines apply for screening and vaccinating of her at-risk household contacts as well as her drug and sexual partners.
A pregnant woman not tested for HBsAg prior to the time of delivery should be tested at that time. The risk of perinatal transmission from an HBV-infected mother to her infant ranges from 10 to 85 percent, according to various studies. If the mother is both HBsAg and HBeAg positive, the risk of transmission is greater. See table 8 for CDC guidelines for vaccinating infants.
Prevention of perinatal transmission of hepatitis B virus: Prenatal screening of all pregnant women for hepatitis B surface antigen. Recommendations of the Immunization Practices Advisory Committee. Morbidity and Mortality Weekly Report 37(22):341-351, June 10, 1988.
Update: Universal precautions for prevention of transmission of human immunodeficiency virus, hepatitis B virus, and other bloodborne pathogens in health-care settings. Morbidity and Mortality Weekly Report 37(24):377-388, June 24, 1988.
Hepatitis B virus: A comprehensive strategy for eliminating transmission in the United States through universal childhood vaccination. Recommendations of the Immunization Practices Advisory Committee. Morbidity and Mortality Weekly Report 40(RR-13):1-25, 1991.
Hepatitis B virus and hepatitis delta virus. In: Mandell, G.L.; Douglas, R.G.; and Bennett, J.E., eds. Principles and Practice of Infectious Diseases. New York: Churchill Livingstone, 1990. pp. 1204-MK31.
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