Hepatitis B

Hepatitis B is a viral infection of the liver, found world-wide, with highest incidence in Africa, East Asia, the Pacific basin, the Amazon basin, the Asian republics of the former Soviet Union, the Caribbean, and the Middle East (except Israel) (see Geographic Pattern of Hepatitis B Prevalence, 1997). The virus may be transmitted by several routes: (1) from mother to child during pregnancy; (2) through exposure to infected blood, either through blood transfusions, contaminated needles, open skin wounds, or other means; (3) by sexual contact. The incubation period ranges from . Symptoms may include fever, malaise, jaundice, nausea, vomiting, and abdominal pain. Most cases resolve slowly but uneventfully. However, a small percentage leads to chronic liver damage (chronic hepatitis or cirrhosis) and sometimes liver cancer.

Most travelers are at low risk for hepatitis B. The vaccine is recommended only for long-term (more than 6 months) travelers who expect to live in rural areas or have close physical contact with the local population in areas where hepatitis B is prevalent. Additionally, the vaccine is recommended for anyone who anticipates sexual contact with the local inhabitants or a possible need for medical, dental, or other treatments while abroad, especially if transfusions or injections may be expected. All health care providers, whether or not they travel, should be immunized against hepatitis B.

Hepatitis B vaccine is safe and highly effective. Two hepatitis B vaccines are currently licensed in the United States: Recombivax HB (Merck and Co., Inc.) (PDF) and Engerix-B (GlaxoSmithKline) (PDF). A full series consists of three intramuscular doses (1.0 ml for adults, 0.5 ml for children from birth to age 19). The second and third doses are given one and six months, respectively, after the first. (Engerix-B has also been licensed for a four-dose series given at 0, 1, 2, and 12 months.) For travelers at high risk for hepatitis B who are going to endemic areas on short notice, hepatitis B vaccine may be given at 0, 7, and 21–28 days, although this schedule has not been approved by FDA.

Side-effects of hepatitis B vaccine, if they occur, are typically mild and may include discomfort at the infection site and low-grade fever. Rarely, severe allergic reactions (anaphylaxis) occur, which contraindicates further doses. Other events have been reported after hepatitis B vaccine (multiple sclerosis, optic neuritis, rheumatoid arthritis, diabetes mellitus, hair loss), but the relationship between the vaccine and these occurrences remains unclear. Preliminary evidence linking hepatitis B vaccine to leukemia has not been supported by other studies (see the World Health Organization). On the basis of limited data, there is no apparent risk to the fetus when the vaccine is given during pregnancy.

A combined hepatitis A and hepatitis B vaccine (Twinrix; GlaxoSmithKline) (PDF) is now available. A full series consists of three intramuscular doses given at times 0, 1, and 6 months, as for hepatitis B vaccine. An accelerated dosing schedule of 0, 7, 21-30 days and a month 12 booster dose was recently approved by the FDA. Adverse reactions appear comparable to those reported for previously licensed hepatitis A and B vaccines. In the United States, the vaccine is approved for those 18 years or older. In other parts of the world, including Canada and Europe, a pediatric formulation (Twinrix Junior) is available. For travelers who require immunization against both types of hepatitis, Twinrix will reduce the number of total injections from five to three, though it will not change the minimum time necessary for immunization. The amount of hepatitis A antigen in Twinrix is half that in single antigen hepatitis A vaccine (Engerix). Hepatitis A antibody levels are high after Twinrix, but it is unknown whether or not the lower dose will affect the duration of immunity. (Two doses of single antigen hepatitis A vaccine confer protection for at least ten years).

From the World Health Organization (WHO)

Hepatitis B (brief introduction)

Hepatitis B fact sheet

Hepatitis B vaccine

Global distribution of hepatitis A, B and C, 2001. Weekly Epidemiological Record, 8 February 2002 (PDF)

Geographic prevalence of hepatitis B, 1997

From the Centers for Disease Control (CDC)

Hepatitis, Viral, Type B

Hepatitis B Fact Sheet