Hepatitis B

  • The Hepatitis B virus is a single stranded DNA virus
  • Consists of 42 nm Dane particle (HbsAg) and 22 nm core (HbcAg)
  • HbsAg - Hepatitis B surface antigen = Australia antigen
  • HbcAg - Hepatitis B core antigen
  • HbsAb - Hepatitis B surface antibody
  • HbeAg - Hepatitis B 'e' antigen
  • In UK prevalence of HbsAg positivity is 1-2%
  • Seen particularly in drug addicts, homosexuals, dialysis patients and occasionally medical staff
  • In Asia, Middle East and South America prevalence is between 20-30%
  • Transmitted by vertical transmission, inoculation, oral and sexual contact
  • Incubation period between 6 weeks and 6 months
  • Period of infectivity is from 6 weeks before onset of symptoms and possibly indefinitely after
  • 10% of infected patients become chronic carriers
  • Risk of chronic infection varies with age at which infection is acquired
    • Less than one year = 90%
    • 1-5 years = 30%
    • Greater than 5 years and adult = 2%

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Clinical pictures

  • Acute hepatitis with clinical recovery
  • Acute fulminating hepatitis leading to death
  • Chronic active hepatitis with risk of cirrhosis and hepatocellular carcinoma

Serological results

HbsAg positive

  • The first indicator of infection and seen throughout course of disease
  • Persistence is marker of failure to clear infection

HbsAb positive

  • Marker of protection due to either previous infection of immunisation

HbeAg positive

  • Closely associated with infectivity of patient

Prevention of infection

  • Avoid contact with virus
    • Care with needles, body fluids etc
  • Hyperimmune anti-Hepatitis B IgG
    • Useful after needle stick injury from high risk patient
    • Ideally given with 24 - 48 hours after exposure
    • Repeated at one month
  • Immunisation
    • All paramedical staff should be immunised
    • Energix B given and repeated at one and 6 months
    • HbsAb levels >1000 u/l = adequate response
    • Confers protection for up to 5 years

Treatment

  • Two modes of treatment
    • Immunomodulation = interferon
    • Viral suppression = nucleoside analogues

Bibliography

Fry D E.  Hepatitis:  risks for the surgeon.  Am Surg 2000;  66:  178-183.

Lai C L, Ratziu V, Yeun M-F, Poynard T.  Viral Hepatitis B.  Lancet 2003; 362: 2089-2094.

Welsh K,  Alexander G J.  Update on chronic viral hepatitis.  Postgrad Med J 2001;  77:  498-505.

 

 
 

Last updated: 05 January 2008

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