About Hepatitis B

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Infectious Agent

Hepatitis B virus (HBV) causes an infection of the liver. HBV is found in highest concentrations in the blood and in lower concentrations in other body fluids (e.g. semen and vaginal secretions). Eight HBV genotypes have been identified.

Occurrence

In Canada, the estimated prevalence of hepatitis B is 0.8% with the highest prevalence reported in immigrant (7.4%) and Inuit (6.9%) populations. Worldwide, about 360 million people have chronic (long-term) infection and an estimated 15% - 25% of persons with chronic hepatitis B infection will die prematurely of liver cirrhosis or liver cancer. In countries where hepatitis B is highly endemic (? 8%), most infections occur in infancy (vertical transmission from an infected mother to her infant) and childhood (horizontal transmission between children and household contacts).

Modes of Transmission

HBV is found mainly in the blood, vaginal secretions, semen, and serous fluids of an infected person. Hepatitis B is efficiently transmitted by percutaneous (through the skin) or mucous membrane exposure through infectious blood, body fluids that contain blood, or specific non-bloody body fluids. 

Clinical Characteristics

The incubation period is approximately six weeks to six months.  A small proportion of HBV infections are clinically recognized; symptoms include tiredness, loss of appetite, and stomach pain.  The appearance of jaundice varies inversely by age, i.e. about half of adults have jaundice and 10% of children.  After initial HBV infection, the rate remaining chronically infected also varies inversely with age: 90% of infants infected at birth, 20% - 50% in children from one to five years, and 1% - 10% of older children/adults.

Diagnosis

Commercial laboratory tests (serological tests) are available to detect hepatitis B infection (HBsAg) and immunity (anti-HBs).  Other tests determine viral load (the HBV DNA level in the blood) and HBV genotypes (A though H).

Treatment

Antiviral medications are available to treat chronic hepatitis B; the aim of treatment is to suppress the ability of the virus to replicate. Medical specialists in viral hepatitis are best able to discuss the various therapeutic options.

Risk Factors

In Canada, the greatest risk for becoming infected is through sharing drug-using equipment and unprotected sex. See below for persons at risk. 

Persons at Risk for Hepatitis B

 Persons at Risk

Level of Risk

 Drug users who share needles or other injecting equipment (works)

High
 Those who 'snort' drugs High
 Those who have unprotected sex with multiple partners High
 Homosexual men Medium
 Individuals from countries where the virus is regularly found (Africa,
 Southeast Asia, the Middle East, Southern and Western Pacific
 Islands, the Amazon Basin,  Haiti and the Dominican Republic).
Medium
 Those who spend time in prison Medium
 Hemophiliacs Low
 Individuals who undergo hemodialysis Low
 Health-care workers, emergency services workers Low
* Source: Adapted from the Public Health Agency of Canada Hepatitis B
  Fact Sheet

Prevention

An effective vaccine to prevent hepatitis B has been available since 1982. A product containing hepatitis B antibodies, hepatitis B immune globulin (HBIG), is available for exposure incidents.

Additional information on hepatitis B can be obtained from the following websites

Alberta Health and Wellness
Notifiable Disease Guidelines – Hepatitis B Acute Case
Notifiable Disease Guidelines – Hepatitis B Chronic Carrier

Canadian Liver Foundation
Hepatitis B

Public Health Agency of Canada
Hepatitis B Fact Sheet

 

 

References

1.      American Academy of Pediatrics. (2006). Hepatitis B. In L. K. Pickering (ed.), Red Book: 2006 Report of the Committee on Infectious Diseases. 27th edition (pp. 335 – 355). Elk Grove Village, Illinois: American Academy of Pediatrics.

2.      American Public Health Association. (2008). Hepatitis B. In D. L. Heyman (ed.), Control of Communicable Diseases Manual, 19th edition, (pp. 284 - 293).Washington. DC: American Public Health Association.

3.      Public Health Agency of Canada. (2006). Canadian Immunization Guide (7th ed.) Minister of Public Works and Government Services Canada. (Catalogue No. HP40-3/2006E)

4.      Zhang, J., Zou, S., & Giulivi, A. (2001).  Hepatitis B in Canada. Canada Communicable Disease Report, Accessed on Feb. 2, 2009.

 

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