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Hepatitis B

CMAJ 1997;156:1033

© 1997 Minister of Health

In 1994, 3078 cases of hepatitis B were reported in Canada.[1] At least 1137 of these were acute and likely newly acquired;[2] however, given the considerable underreporting associated with public health surveillance, the actual number of acute cases may be several times higher. The incidence rate of acute hepatitis B appears to be decreasing, although the reasons for this are not clear.[2] In Canada, transmission is primarily sexual, although parenteral and perinatal transmission also occur. Progression to chronic (carrier) infection is inversely related to age; 5% of people infected as adults but 90% of those infected in the first year of life progress. Chronic infection can have long-term sequelae, such as cirrhosis and hepatocellular carcinoma. It is likely that considerably more than 100 000 Canadians have chronic hepatitis B.

Chronic infection is highly endemic in all of Africa, Southeast Asia, the Middle East (except Israel), the southern and western Pacific islands, the interior Amazon Basin, Haiti and the Dominican Republic. Immigrants from these areas are more likely to have chronic infection than people born in Canada. Chronic infection among such immigrants can result in the transmission of hepatitis B to other family members (not just sexual partners) and from child to child between households.[3]

Two hepatitis B vaccines are licensed in Canada: Recombivax HB (Merck Sharp & Dohme) and Engerix-B (SmithKline Beecham Pharma). All provinces and territories except Manitoba now have universal school-based immunization programs. New Brunswick, PEI and the Northwest Territories also have universal infant immunization programs. These programs are expected to reduce the incidence of hepatitis B substantially in the next decade. Nevertheless, vaccination for people in high-risk groups, including certain children in immigrant households, is still recommended (see Appendix).

It is recommended that pregnant women be screened for hepatitis B and that the infants of infected women be given hepatitis B immune globulin (HBIG) immediately after birth, followed by vaccine within 7 days and at 1 and 6 months after the first dose.[4,5] These measures can prevent 90% of chronic infections among these infants. Unfortunately, screening and vaccination rates may be less than optimal in some areas of Canada.[6,7]

In the health care setting, hepatitis B poses a risk to both patients and workers. In a recent Ontario outbreak, 75 cases were linked to the reuse of subdermal EEG electrodes by a technician who carried the hepatitis B e antigen.[8] The development of national guidelines for preventing the transmission of blood-borne pathogens in the health care setting and for dealing with health care workers infected with these pathogens is being coordinated by the Laboratory Centre for Disease Control (for information call 613 952-5221). Guidelines have just been published on hepatitis B (and C and HIV) postexposure prophylaxis for health care workers.[9] Hepatitis B immunization of health care workers at occupational risk remains an important means of reducing transmission in the health care setting.

Martin L. Tepper, MD, MHSc
Paul R. Gully, MB, ChB
Division of Blood-borne Pathogens
Laboratory Centre for Disease Control
Ottawa, Ont.

References

  1. Notifiable Diseases Annual Summary, 1994. Can Commun Dis Rep 1996;22(S2):66-7.
  2. Acute hepatitis B incidence in Canada. Can Commun Dis Rep. In press.
  3. Franks AL, Berg CJ, Kane MA, Browne BB, Sikes K, Elsea WR, et al. Hepatitis B virus infection among children born in the United States to Southeast Asian refugees. N Engl J Med 1989;321:1301-5.
  4. Canadian immunization guide. 4th ed [cat no H49-8/1993E]. Ottawa: National Health and Welfare, 1993.
  5. Society of Obstetricians and Gynaecologists of Canada. Healthy beginnings: guidelines for care during pregnancy and childbirth. Ottawa: The Society; 1995.
  6. Carsley J, Gyorkos TW, Abrahamowicz M, Tannenbaum TN, Delage G, Marchand S. Hepatitis B screening of pregnant women [abstract P29]. Canadian National Immunization Conference, Toronto, Dec 8­11, 1996.
  7. Wallace E, Bangura H, Wasfy S, Fearon M. Assessment of the Ontario hepatitis B prenatal screening program [abstract C3]. Canadian National Immunization Conference, Toronto, Dec 8­11, 1996.
  8. Johnson I. Hepatitis B -- EEG clinics outbreak investigation: final report, January 1997. Toronto: Ontario Ministry of Health, 1997.
  9. An integrated protocol to manage health care workers exposed to bloodborne pathogens. Can Commun Dis Rep 1997;23(S2):1-14.

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| CMAJ April 1, 1997 (vol 156, no 7) / JAMC le 1er avril 1997 (vol 156, no 7) |