HEPATITIS B VIRUS (HBV)
Unlike hepatitis A, which is transmitted primarily by the fecal–oral route, hepatitis B is transmitted primarily through blood (percuta-neous and permucosal routes). HBV has been found in blood, saliva, semen, and vaginal secretions and can be transmitted through mucous membranes and breaks in the skin. HBV is also trans-ferred from carrier mothers to their babies, especially in areas with a high incidence (ie, Southeast Asia). The infection is usually not via the umbilical vein, but from the mother at the time of birth and during close contact afterward.
HBV has a long incubation period. It replicates in the liver and remains in the serum for relatively long periods, allowing transmission of the virus. Those at risk for developing hepatitis B include surgeons, clinical laboratory workers, dentists, nurses, and respiratory therapists. Staff and patients in hemodialysis and oncology units and sexually active homosexual and bisexual men and injection drug users are also at increased risk. Screening of blood donors has greatly reduced the occurrence of hepatitis B after blood transfusion.
Most people (>90%) who contract hepatitis B infections will develop antibodies and recover spontaneously in 6 months. The mortality rate from hepatitis B has been reported to be as high as 10%. Another 10% of patients who have hepatitis B progress to a carrier state or develop chronic hepatitis with persistent HBV infection and hepatocellular injury and inflammation. It remains a major cause of cirrhosis and hepatocellular carcinoma world-wide (Chart 39-8).
Clinically, the disease closely resembles hepatitis A, but the incu-bation period is much longer (1 to 6 months). Signs and symp-toms of hepatitis B may be insidious and variable. Fever and respiratory symptoms are rare; some patients have arthralgias and rashes. The patient may have loss of appetite, dyspepsia, abdom-inal pain, generalized aching, malaise, and weakness. Jaundice may or may not be evident. If jaundice occurs, light-colored stools and dark urine accompany it. The liver may be tender and enlarged to 12 to 14 cm vertically. The spleen is enlarged and pal-pable in a few patients; the posterior cervical lymph nodes may also be enlarged. Subclinical episodes also occur frequently.
HBV is a DNA virus composed of the following antigenic particles:
• HBcAg—hepatitis B core antigen (antigenic material in an inner core)
• HBsAg—hepatitis B surface antigen (antigenic material on surface of HBV)
• HBeAg—an independent protein circulating in the blood
• HBxAg—gene product of X gene of HBV/DNA
Each antigen elicits its specific antibody and is a marker for different stages of the disease process:
• anti-HBc—antibody to core antigen or HBV; persists dur-ing the acute phase of illness; may indicate continuing HBV in the liver
• anti-HBs—antibody to surface determinants on HBV; de-tected during late convalescence; usually indicates recovery and development of immunity
• anti-HBe—antibody to hepatitis B e-antigen; usually signi-fies reduced infectivity
• anti-HBxAg—antibody to the hepatitis B x-antigen; may indicate ongoing replication of HBV
HBsAg appears in the circulation in 80% to 90% of infected pa-tients 1 to 10 weeks after exposure to HBV and 2 to 8 weeks before the onset of symptoms or an increase in transferase (transaminase) levels. Patients with HBsAg that persists for 6 or more months after acute infection are considered HBsAg carriers (Befeler & Di Bisceglie, 2000). HBeAg is the next antigen of HBV to appear in the serum. It usually appears within a week of the appearance of HBsAg and before changes in aminotransferase levels, disappearing from the serum within 2 weeks. HBV DNA, detected by poly-merase chain reaction testing, appears in the serum at about the same time as HBeAg. HBcAg is not always detected in the serum in HBV infection.
About 15% of American adults are positive for anti-HBs, which indicates that they have had hepatitis B. Anti-HBs may be positive in as many as two thirds of IV/injection drug users.
The goals of prevention are to interrupt the chain of transmis-sion, to protect people at high risk with active immunization through the use of hepatitis B vaccine, and to use passive immu-nization for unprotected people exposed to HBV.
Continued screening of blood donors for the presence of hepati-tis B antigens will further decrease the risk of transmission by blood transfusion. The use of disposable syringes, needles, and lancets and the introduction of needleless IV administration sys-tems reduce the risk of spreading this infection from one patient to another or to health care personnel during the collection of blood samples or the administration of parenteral therapy. Good personal hygiene is fundamental to infection control. In the clin-ical laboratory, work areas should be disinfected daily. Gloves are worn when handling all blood and body fluids as well as HBAg-positive specimens, or when there is potential exposure to blood (blood drawing) or to patients’ secretions. Eating and smoking are prohibited in the laboratory and in other areas exposed to se-cretions, blood, or blood products. Patient education regarding the nature of the disease, its infectiousness, and prognosis is a crit-ical factor in preventing transmission and protecting contacts.
Active immunization is recommended for individuals at high risk for hepatitis B (eg, health care personnel and hemodialysis patients). In addition, individuals with hepatitis C and other chronic liver diseases should receive the vaccine (CDC, 1999).
A yeast-recombinant hepatitis B vaccine (Recombivax HB) is used to provide active immunity. Long-term studies of healthy adults and children indicate that immunologic memory remains intact for at least 5 to 10 years, although antibody levels may be-come low or undetectable. Measurable levels of antibodies may not be essential for protection. In those with normal immune sys-tems, booster doses are not generally required. The CDC (2002) does not recommend booster doses at this time except for he-modialysis patients. The need for booster doses may be revisited if reports of hepatitis B increase or an increased prevalence of the carrier state develops, indicating that protection is declining.
A hepatitis B vaccine prepared from plasma of humans chroni-cally infected with HBV is used only rarely and in patients who are immunodeficient or allergic to recombinant yeast-derived vaccines.
Both forms of the hepatitis B vaccine are administered in-tramuscularly in three doses, the second and third doses 1 and 6 months after the first dose. The third dose is very important in producing prolonged immunity. Hepatitis B vaccination should be administered to adults in the deltoid muscle. Antibody response may be measured by anti-HBs levels 1 to 3 months after complet-ing the basic course of vaccine, but this testing is not routine and not currently recommended. Individuals who fail to respond may benefit from one to three additional doses (Koff, 2001).
People at high risk, including nurses and other health care per-sonnel exposed to blood or blood products, should receive active immunization. Health care workers who have had frequent con-tact with blood are screened for anti-HBs to determine whether im-munity is already present from previous exposure. The vaccine produces active immunity to HBV in 90% of healthy people (Koff, 2001). It does not provide protection to those already exposed to HBV and provides no protection against other types of viral hep-atitis. Side effects of immunization are infrequent; soreness and redness at the injection site are the most common complaints.
Because hepatitis B infection is frequently transmitted sexually, hepatitis B vaccination is recommended for all unvaccinated per-sons being evaluated for a sexually transmitted disease (STD). It is also recommended for those with a history of an STD, per-sons with multiple sex partners, those who have sex with injection drug users, and sexually active men who have sex with other men (CDC, 2002).
Universal childhood vaccination for hepatitis B prevention has been instituted in the United States. Vaccination was initially targeted for select high-risk populations, but the U.S. Public
Health Service and the CDC (1999) have endorsed universal vac-cination of all infants. Catch-up vaccination is also recommended for all children and adolescents up to the age of 19 who were not previously immunized. Studies (Chang, 2000; Wu et al., 1999) show that universal vaccination of all newborns in endemic areas has dramatically reduced the carrier rate among children and the incidence of childhood hepatocellular carcinoma. In the United States, studies regarding the effectiveness of the vaccine are ongo-ing, but it is known that clinical infection is rarely observed during long-term follow-up of known responders (ie, health care workers) who seroconverted within 3 months of the third dose of vaccine (Bircher et al., 1999). Development of chronic carrier states has not been reported in adult responders to the vaccine.
Hepatitis B immune globulin (HBIG) provides passive immunity to hepatitis B and is indicated for people exposed to HBV who have never had hepatitis B and have never received hepatitis B vaccine. Specific indications for postexposure vaccine with HBIG include: (1) inadvertent exposure to HBAg-positive blood through percu-taneous (needlestick) or transmucosal (splashes in contact with mu-cous membrane) routes, (2) sexual contact with people positive for HBAg, and (3) perinatal exposure (babies born to HBV-infected mothers should receive HBIG within 12 hours of delivery). HBIG, which provides passive immunity, is prepared from plasma selected for high titers of anti-HBs. Prompt immunization with HBIG (within hours to a few days after exposure to hepatitis B) increases the likelihood of protection. Both active and passive immunization are recommended for people exposed to hepatitis B through sexual contact or through percutaneous or transmucosal routes. If HBIG and hepatitis B vaccine are administered at the same time, separate sites and separate syringes should be used. Prophylaxis with high doses of HBIG started at the time of liver transplantation and con-tinued indefinitely improves survival by thwarting recurrence of hepatitis B (Bacon & Di Bisceglie, 2000). There has been no evi-dence that HIV infection can be transmitted by HBIG.
The elderly patient who contracts hepatitis B has a serious risk of severe liver cell necrosis or fulminant hepatic failure, particularly if other illnesses are present. The patient is seriously ill and the prog-nosis is poor, so efforts should be undertaken to eliminate other factors (eg, medications, alcohol) that may affect liver function.
The goals of treatment are to minimize infectivity, normalize liver inflammation, and decrease symptoms. Of all the agents that have been used to treat chronic type B viral hepatitis, alpha in-terferon as the single modality of therapy offers the most promise. This regimen of 5 million units daily or 10 million units three times weekly for 4 to 6 months results in remission of disease in approximately one third of patients (Befeler & Di Bisceglie, 2000). The long-term benefits of this treatment are being as-sessed. Interferon must be administered by injection and has sig-nificant side effects, including fever, chills, anorexia, nausea, myalgias, and fatigue. Late side effects are more serious and may necessitate dosage reduction or discontinuation. These include bone marrow suppression, thyroid dysfunction, alopecia, and bacterial infections.
Two antiviral agents (lamivudine [Epvir] and adefovir [Hep-sera]) oral nucleoside analogs, have been approved for use in chronic hepatitis B in the United States. Viral resistance may be an issue with these agents, and studies of their effectiveness alone and in combination with other therapies are ongoing (Befeler & Di Bisceglie, 2000).
Bed rest may be recommended, regardless of other treatment, until the symptoms of hepatitis have subsided. Activities are re-stricted until the hepatic enlargement and elevated levels of serum bilirubin and liver enzymes have disappeared. Gradually increased activity is then allowed.
Adequate nutrition should be maintained; proteins are re-stricted when the liver’s ability to metabolize protein byproducts is impaired, as demonstrated by symptoms. Measures to control the dyspeptic symptoms and general malaise include the use of antacids and antiemetics, but all medications should be avoided if vomiting occurs. If vomiting persists, the patient may require hospitalization and fluid therapy. Because of the mode of transmission, the patient is evaluated for other bloodborne diseases (eg, HIV infection).
Convalescence may be prolonged, with complete symptomatic recovery sometimes requiring 3 to 4 months or longer. During this stage, gradual resumption of physical activity is encouraged after the jaundice has resolved.
The nurse identifies psychosocial issues and concerns, partic-ularly the effects of separation from family and friends if the pa-tient is hospitalized during the acute and infective stages. Even if not hospitalized, the patient will be unable to work and must avoid sexual contact. Planning is required to minimize alterations in sensory perception. Planning that includes the family helps to decrease their fears and anxieties about the spread of the disease.
Because of the prolonged period ofconvalescence, the patient and family must be prepared for home care. Provision for adequate rest and nutrition must be ensured. The nurse informs family members and friends who have had in-timate contact with the patient about the risks of contracting he-patitis B and makes arrangements for them to receive hepatitis B vaccine or hepatitis B immune globulin as prescribed. Those at risk must be aware of the early signs of hepatitis B and of ways to reduce risk to themselves by avoiding all modes of transmission. Patients with all forms of hepatitis should avoid drinking alcohol.
Follow-up visits by a home care nurse may beneeded to assess the patient’s progress and answer family mem-bers’ questions about disease transmission. A home visit also per-mits assessment of the patient’s physical and psychological status and the patient and family’s understanding of the importance of adequate rest and nutrition. The nurse also reinforces previous instructions. Because of the risk of transmission through sexual intercourse, strategies to prevent exchange of body fluids are ad-vised, such as abstinence or the use of condoms. The nurse em-phasizes the importance of keeping follow-up appointments and participating in other health promotion activities and recom-mended health screenings.