Hepatitis B

(HBV)
  • Hepadna virus - dsDNA
  • Important antigens HBsAg (surface antigen), HBcAg (core antigen), HbeAg, (derived from core antigen)
  • Transmitted by blood products, sexual contact
  • virus replication is not directly responsible for lysis of the hepatocyte

    • the immune response to the infection is

Symptoms

  • Incubation 1-3 months
  • prodrome of rash and arthralgia
  • Malaise
  • anorexia
  • nausea
  • jaundice
    • absence does not exclude diagnosis
  • ? acute liver failure

Risk Factors

  • Needle sharing
    • Tattoos
    • IV drug use
  • Unprotected sex
    • homosexuals
    • prostitutes
  • Haemophiliacs
  • Health workers
  • Haemodialysis
  • Babies of infected mothers

Investigations

  • Liver function tests
    • bilirubin raised
    • ALT, AST very raised
  • Hepatitis B serology

    Surface antigen (HBsAg) and respective Antibody (HBsAb), core antigen (HBeAg) and respective antibody (HBcAb) - IgM and IgG

    • early acute infection
      • surface antigen +ve
      • e antigen +ve
      • surface antibody -ve
      • core antibody -ve
    • Late acute
      • e antigen may disappear
      • IgM core antibody may be present
    • Chronic
      • surface antigen +ve
      • highly infectious if
        • e antigen positive
      • less infectious if
        • e antigen negative
        • c antibody positive (IgG)
    • recovered acute
      • HBeAb disappears first (not normally measured),  then HBsAb, then HbcAb
    • vaccinated
      • HBsAb +ve
      • HBeAg -ve
      • HBsAg -ve

Carrier status

  • approximately 10%
  • less likely if vigorous immune response (but also more severe illness)
  • immunodeficient patients - milder disease, increased risk of carrier status
  • infants 90-95%, 1-3 years - 23%, university age 3% (taiwan)
  • males > females

Complications

  • Fulminant hepatic failure
  • Relapse
  • Prolonged cholestasis
  • Chronic hepatitis
  • Cirrhosis
  • hepatocellular carcinoma (after 20-30 years risk 200x increased)
  • Polyarteritis Nodosa

Treatment

Prophylaxis

  • Two or 3 doses of recombinant surface antigen (HBsAg)
  • Spread: virus in semen and saliva. (iv route, close personal contact- esp male homosexuals, vertical transmission)

 

  • Acute Hep B
  •  Symptomatic treatment and rest. Avoidance (needle exchange) and vaccination.
  • Lamivudine and interferon alfa may be tried.

 

  • Chronic Hep B
  •  (HbsAg +ve; DNA +ve)
  • Combined prophylaxis (vaccination and immunoglobulin) for all  healthcare (and related) personnel, travellers, haemophiliacs as well as children at risk. 500IU specific hep B immunoglobulin (HBIG); 200IU for newborns + vaccine (im).

 

 

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