Mode of transmisison: infected blood/body fluids during childbirth (vertical); sexual intercourse/needles/contact with broken ksin - horizontal

Incubation: 45-180d, commonly 60-90d

Period of infectivity: 2-3wks prior onset; usually 203mo after acute hepB - as long as HBsAg continues to be present in blood

Vaccines: contain HBsAg

• HepB

• DTaP-IPV-HepB/Hib

Schedule: 6wk, 3mo, 5mo

efficacy: protection expected to be lifelong; boosters not recommended. 85-95%. Age = biggest factor

Herd:

• Partially double-stranded DNA virus

• HBeAG = correlated with viral replication

  • acute hepB

  • chronic HBV infection with high viral load

Clinical

• borad specturm

  • subclinical

  • fulminant hepatitis

• persistent infection: Chronic liver diease -> cirrhosis/HCC

• Acute hepatits;

  • infects liver cells

  • releasing large amounts of HBsAg

  • hosts immune response = cell death

  • symptoms

    • fever, jaundice, malaise, anorexia, N/V, myalgia, abdo pain

    • jaundice usually within 2wks

  • clinical signs resolve 1-3mo later

  • small risk of acute liver failure (\<1%)

• Chronic HBV infection

  • persistence of HBsAg for >6mo

  • infants seldom mount immune response

  • early years; high rates of viral replication common

    • HBeAg

    • high levels of HBV DNA

  • later years

    • HBeAg cleared

    • if HBeAg cleared and HBsAg + = carriers