Sandra S. Chaves

Infectious Agent

Hepatitis B is caused by the hepatitis B virus (HBV), a small, circular, partially double-stranded DNA molecule in the Hepadnaviridae family.

Mode of Transmission

HBV is transmitted through activities that involve contact with blood or blood-derived fluids. Such activities include the following:

• Unprotected sex with an HBV-infected partner
• Shared needles used for injection of illegal drugs
• Shared glucose-monitoring equipment
• Work in health-care fields (e.g., medical, dental, laboratory) that entails direct exposure to potentially infected human blood
• Transfusions with blood or blood products that have not been screened for HBV
• Dental, medical, or cosmetic (e.g., tattooing, body piercing) procedures with needles or other equipment that are contaminated with HBV

In addition, open skin lesions, such as those due to impetigo, scabies, or scratched insect bites, can play a role in HBV transmission if direct exposure to wound exudates from HBV-infected persons occurs.

Occurrence

• The prevalence of chronic HBV infection is low (<2%) in the general population in Northern and Western Europe, North America, Australia, New Zealand, Mexico, and southern South America (Map 2-2).
• The prevalence of chronic HBV infection is intermediate (2%–7%) in South, Central, and Southwest Asia, Israel, Japan, Eastern and Southern Europe, Russia, most areas surrounding the Amazon River basin, Honduras, and Guatemala (see Map 2-2).
• The prevalence of chronic HBV infection is high (≥8%) in all socioeconomic groups in: all of Africa; Southeast Asia, including China, Korea, Indonesia, and the Philippines; the Middle East, except Israel; South and Western Pacific islands; the interior Amazon River basin; and certain parts of the Caribbean (Haiti and the Dominican Republic) (see Map 2-2).

Risk for Travelers

There are no data with which to assess the risk for HBV infection among U.S. travelers. The risk for HBV infection for international travelers is considered generally low, except for travelers to countries where the prevalence of chronic HBV infection is intermediate or high. Some travelers, such as adventure travelers, Peace Corps volunteers, missionaries, and military personnel, may be at increased risk for infection.

Situations or activities that may carry increased risk for HBV infection for travelers while overseas include the following:

• An injury or illness that requires invasive medical attention (e.g., injection, IV drip, transfusion, stitching)
• Dental treatment
• Unprotected sexual contact
• Sharing illegal drug injection equipment
• Skin-perforation practices (e.g., tattooing, ear piercing, acupuncture)
• Cosmetic practices with risk for skin perforation (e.g., manicure/pedicure)
• Sharing personal grooming items (e.g., earrings, toothbrush, razor)

Clinical Presentation

• Incubation period of hepatitis B is typically 90 days (range: 60–150 days) from exposure to onset of jaundice.
• Constitutional symptoms such as malaise and anorexia may precede jaundice by 1–2 weeks.
• Clinical symptoms and signs include nausea, vomiting, abdominal pain, and jaundice.
• Skin rashes, joint pain, and arthritis may occur.
• Infants, children<5 years of age, and immunosuppressed adults with newly acquired HBV infection typically are asymptomatic.
• Infected persons ≥5 years of age, including immunocompetant adults, 30%–50% have initial clinical signs or symptoms.
• The case–fatality rate of acute hepatitis B is approximately 1%.
• Acute HBV infection causes chronic (long-term) infection in 30%–90% of persons infected as infants or young children and in <5% of adolescents and adults.
• Chronic infection can lead to chronic liver disease, liver scarring (cirrhosis), and liver cancer.

Diagnosis

At least one serologic marker is present during each of the different phases of HBV infection. The serologic markers are typically used to differentiate between acute, resolving, and chronic infection (Table 2-8).

Treatment

No specific treatment is available for acute illness caused by hepatitis B. Antiviral drugs are approved for the treatment of chronic hepatitis B.

Preventive Measures for Travelers

Vaccine

• Hepatitis B vaccination should be administered to all unvaccinated persons traveling to areas with intermediate to high levels of endemic HBV transmission (i.e., with hepatitis B surface antigen [HBsAg] prevalence ≥2%).
• Hepatitis B vaccination is currently recommended for all U.S. residents who work in health-care fields (e.g., medical, dental, laboratory) that involve potential exposure to human blood.
• All unvaccinated U.S. children and adolescents (<19 years of age) should receive hepatitis B vaccine.
• Unvaccinated persons who have indications for hepatitis B vaccination independent of travel should be vaccinated (e.g., men who have sex with men, injection drug users, anyone who has recently had a sexually transmitted disease or has had more than one sex partner in the previous 6 months).

Vaccine Dose and Administration

• The vaccine is usually administered as a three-dose series on a 0-, 1-, and 6-month schedule (see Table 2-9). The second dose should be given 1 month after the first dose; the third dose should be given at least 2 months after the second dose and at least 4 months after the first dose.
• Alternatively, the vaccine ENGERIX-B, manufactured by GlaxoSmithKline, is also approved for administration on a four-dose schedule at 0, 1, 2, and 12 months.
• There is also a two-dose schedule for RECOMBIVAX HB, a vaccine produced by Merck & Co., Inc., which has been licensed for children and adolescents 11–15 years of age. Using the two-dose schedule, the adult dose of RECOMBIVAX HB is administered, with the second dose given 4–6 months after the first dose.
• A three-dose series that has been started with one brand of vaccine may be completed with the other brand.
• TWINRIX, manufactured by GlaxoSmithKline, is a combined hepatitis A and hepatitis B vaccine licensed for persons 18 years of age or older. Primary immunization consists of three doses, given on a 0-, 1-, and 6-month schedule.

Special Situations

• Ideally, vaccination should begin at least 6 months before travel so the full vaccine series can be completed before departure. Because some protection is provided by one or two doses, the vaccine series should be initiated, if indicated, even if it cannot be completed before departure. Optimal protection, however, is not conferred until after the final vaccine dose. Travelers should be advised to return for completion of the vaccine series.
• Although not FDA approved, an accelerated vaccine schedule could be used for those traveling to endemic areas at short notice and facing imminent exposure because of behavioral risks or to emergency responders to disaster areas. The monovalent hepatitis B vaccines can be used at 0, 7, and 21–28 days. If an accelerated schedule is used, the patient should receive a booster dose at least 6 months after the start of the series to promote long-term immunity.
• An accelerated vaccine schedule with TWINRIX (hepatitis A and hepatitis B vaccine) can also be used (doses at 0, 7, and 21–30 days). In this situation, a booster dose should be given at 12 months to promote long-term immunity.
• For children and adults whose immune status is normal, booster doses of vaccine are not recommended. Serologic testing to assess antibody levels is not necessary for most vaccinees (see the Vaccine Recommendations for Infants and Children section in Chapter 7).

Vaccine Safety and Adverse Reactions

• Hepatitis B vaccines have been shown to be safe for persons of all ages. Pain at the injection site (3%–29%) and elevated temperature higher than 37.7° C (99.9° F) (1%–6%) are the most frequently reported side effects among vaccine recipients.
• These vaccines should not be administered to persons with a history of hypersensitivity to any vaccine component, including yeast. The vaccine contains a recombinant protein (HBsAg) that is noninfectious. Limited data indicate that there is no apparent risk of adverse events to the developing fetus when hepatitis B vaccine is administered to pregnant women. HBV infection affecting a pregnant woman can result in serious disease for the mother and chronic infection for the newborn. Neither pregnancy nor lactation should be considered a contraindication for vaccination.

Other Preventive Measures

• As part of the pre-travel education process, all travelers should be given information about the risks for hepatitis B and other bloodborne pathogens from contaminated medical equipment, injection drug use, or sexual activity and informed of prevention measures (see below), including hepatitis B vaccination, that can be used to prevent transmission of HBV.
• Regardless of destination, all persons who may engage in practices that put them at risk for HBV infection during travel should receive hepatitis B vaccination if previously unvaccinated.
• Any adult seeking protection from HBV infection should be vaccinated. Acknowledgment of a specific risk factor is not a requirement for vaccination.
• Behavioral preventive measures for HBV infection are similar to those for HIV infection and AIDS.
• When seeking medical or dental care, travelers should be advised to be alert to the use of medical, surgical, and dental equipment that has not been adequately sterilized or disinfected, reuse of contaminated equipment, and unsafe injecting practices (e.g., reuse of disposable needles and syringes).
• HBV and other bloodborne pathogens (e.g., HIV and hepatitis C) can be transmitted if tools are not sterile or if the tattoo artist or piercer does not follow other proper infection-control procedures (e.g., washing hands, using latex gloves, and cleaning and disinfecting surfaces and instruments).
• Travelers should be advised to consider the health risks in deciding to get a tattoo or body piercing in areas where adequate sterilization or disinfection procedures might not be available or practiced.

References

1. CDC. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices (ACIP) Part II: immunization of adults. MMWR Recomm Rep. 2006;55(RR-16):1–25.
2. CDC. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices (ACIP) Part 1: immunization of infants, children, and adolescents. MMWR Recomm Rep. 2005;54(RR-16):1–23.
3. Mast E, Goldstein S, Ward JL. Hepatitis B vaccine. In: Plotkin SA, Orenstein WA, editors. Vaccines. 5th ed. Philadelphia: W.B. Saunders; 2004. p. 299–337.
4. Simonsen L, Kane A, Lloyd J, et al. Unsafe injections in the developing world and transmission of bloodborne pathogens: a review. Bull World Health Organ. 1999;77(10):789–800.
5. Sagliocca L, Stroffolini T, Amoroso P, et al. Risk factors for acute hepatitis B: a case–control study. J Viral Hepat. 1997;4(1):63–6.
6. Lok AS, McMahon BJ. Practice Guidelines Committee, American Association for the Study of Liver Diseases (AASLD). Chronic hepatitis B: update of recommendations. Hepatology. 2004;39(3):857–61.
7. CDC. Updated U.S. Public Health Service guidelines for the management of occupational exposures to HBV, HCV and HIV and recommendations for postexposure prophylaxis. MMWR Recomm Rep. 2001;50(RR-11):1–42.
8. Bock HL, Loscher T, Scheiermann N, et al. Accelerated schedule for hepatitis B immunization. J Travel Med.1995;2(4):213–7.
9. Long GE, Rickman LS. Infectious complications of tattoos. Clin Infect Dis. 1994;18(4):610–9. Review.
10. Mariano A, Mele A, Tosti ME, et al. Role of beauty treatment in the spread of parenterally transmitted hepatitis viruses in Italy. J Med Virol. 2004;74(2):216–20.
11. CDC. Provisional Recommendations for Hepatitis B vaccination of adults – October 2005. [cited 2006 Oct 31]. Available from: www.cdc.gov/nip/recs/provisional_recs/hepB_adult.pdf (PDF).