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Hepatitis B

Hepatitis B. Kevin Hyer MS3. Objectives. Epidemiology Transmission Clinical Manifestations Sequelae Treatment Prevention. Epidemiology. Relatively uncommon in the United States due to precautions and vaccinations In 2004 there were about 350 million infected worldwide

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Hepatitis B

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  1. Hepatitis B Kevin Hyer MS3

  2. Objectives • Epidemiology • Transmission • Clinical Manifestations • Sequelae • Treatment • Prevention

  3. Epidemiology • Relatively uncommon in the United States due to precautions and vaccinations • In 2004 there were about 350 million infected worldwide • Under 0.5% were those in the United States • In low prevalence areas, HBV is spread mainly by sharing needles and unprotected sex • Europe and USA • In high prevalence areas, HBV is spread mainly through childbirth • China and South East Asia

  4. Epidemiology

  5. Spread of Infection • HBV is spread through infectious blood or body fluids such as semen or vaginal fluids • HBV does not spread via mother’s breast milk.

  6. Hepatitis B Virus • Hepadnavirus • DNA • Replicates in hepatocytes • Cytotoxic T lymphocytes cause most of the damage while trying to combat HBV

  7. Acute vs. Chronic HBV • Infection is cleared within weeks to months • Chronic HBC is defined by persistence of HBsAg in the blood for more than 6 months • 95% of adults and older children are able to clear the infection and prevent chronic HBV • 30% of younger children are able to clear the infection • 5% of infants are able to clear the infection and prevent chronic HBV

  8. Acute vs. Chronic HBV

  9. Clinical Manifestations • Considerable overlap with HAV and HCV • Incubation period of 60 -180 days • Preicteric phase • Lasts for 1 week • HA, N/V • Anorexia • Malaise • Abdominal discomfort • Precedes onset of clinically detectable disease in most cases • Infants may have immune complexes accompanied by urticaria and arthritis before the onset of icterus

  10. Clinical Manifestations • Icteric Phase • Jaundice and tender hepatomegaly are the most common findings • Prodromal symptoms may abate during this phase • Particularly in children • Asymptomatic or mild, nonspecific illness without icterus is common with HAV, HBV, and HCV • Especially in young children

  11. Clinical Manifestations • Resolution • Hepatic enzymes may increase 15 – 20 fold • Hyperbilirubinemia and normalization of transaminases may take 6 to 8 weeks.

  12. Chronic problems • Over 90% of perinatal infections become chronic HBV infections • Chronic HBsAg carriers are usually HBeAg negative and have no clinical or serologic evidence of active hepatitis unless there is superinfection with HDV • Approximately 10 – 15% of HBsAg carriers eventually clear HBsAg • <1% progress to Fulminant liver failure • There is an increased risk of hepatocellular carcinoma

  13. Prevention • HBV vaccine is recommended for routine immunization of all infants beginning at birth • Vaccination alone without HBIG may prevent 75% of perinatal HBV transmission cases and approximately 95% of symptomatic childhood HBV infections • Routine prenatal screening for HBV is recommended for all pregnant women in the United States

  14. Treatment • Infants born to HBsAg+ mothers should receive HBV vaccine and hepatitis B immunoglobulin (0.5mL) within 12 hours of birth (no later than 1 week of age) • With subsequent vaccine doses at 1 month and 6 months of age • Followed by testing for HBsAg and anti-HBs at 9 – 15 months of age • Postexposure prophylaxis of unvaccinated persons using HBIG and vaccine is recommended following a needle stick injury with blood from a HBsAg+ patient and for household members with intimate contact, including sex partners

  15. Treatment • Chronic HBV may be treated with interferon alpha- 2b or lamivudine • Most of these treatment regimens have been used on adults • Interferon is usually not effective during infection early in life due to the infection being in an immune tolerant phase • Decision to treat is based on the patient’s current age, age at HBV acquisition, development of mutations during therapy, and stage of the viral infection

  16. Summary • The prevalence of infantile HBV is low in the US in comparison to many other countries due to routine prenatal screening and the effectiveness of the HBV vaccine and HBIG treatment. • If mother is HBV+, treat baby with HBV vaccine at birth and HBIG within the first 12 hours of life. • Interferon is typically only used for adults

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