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(MMWR 2006;55:No. RR-7)

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Pathophysiology

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  • Transmission primarily fecal:oral; close person-to-person contact or ingestion of contaminated food; typically self-limiting infection

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Diagnosis & Evaluation

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  • Causes acute viral hepatitis; symptomatic risk ↑ with age; children may be asymptomatic
  • Signs/symptoms: fever, lethargy, nausea, jaundice, dark urine, ↑ LFTs; typically <2mo, may persist for up to 6mo
  • Incubation period ∼28d → peak infective period 2wk before onset of jaundice or ↑ LFTs

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Treatment

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  • No specific therapy; treatment is supportive
  • Prevention: → vaccination (∼50% HAV cases have no identifiable risk factor)
    • All children at age 1y; travelers to endemic regions; men who have sex with men; illicit drug users (injection & noninjection); clotting factor disorders (ex. hemophilia); those who work with HAV-infected animals or in HAV research laboratory; chronic liver disease; chronic HBV infection; anyone who desires vaccination
  • Pre/postexposure prophylaxis
    • Immune globulin (IG): IM 0.02mL/kg for postexposure or short-term preexposure prophylaxis, 0.5mL/kg for longer term (3–5mo) preexposure prophylaxis

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Pathophysiology

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(Hepatology 2009;50:661; N Engl J Med 2004;350:1118)

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  • Transmitted by contact with infectious body fluids; primarily vertical transmission from mother to child, IVDU, sexual contact
  • Infection may be self-limiting or chronic; risk for chronic infection inversely related to age
    • Chronic hepatocyte injury → cell destruction due to immune response vs direct injury from viral infection

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Evaluation

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  • HBV screening recommended for high-risk populations
    • Born in high HBV–risk areas (Hepatology 2009;50:661); U.S.-born if not vaccinated as infant & parents from endemic region; HbsAg+ household or sexual partners; IVDU; multiple sexual partners or history of sexually transmitted disease; men who have sex with men; prisoners; chronically ↑ LFTs; HCV or HIV infection; renal dialysis; pregnant women; immunosuppression
  • Vaccination (MMWR 2006;55:No. RR-16; MMWR 2005;54:No. RR-6)
    • All infants at birth → HBV vaccine & hepatitis B immune globulin (HBIG) <12h after birth for infants born to HBsAg+ mothers or mothers with unknown status
    • All persons <19yo previously unvaccinated
    • Any unvaccinated adult at risk for HBV or who wishes to be vaccinated

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Treatment

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(Hepatology 2009;50:661)

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  • Timing of antiviral initiation based on antigen status, viral count, & LFTs
  • 1st-line monotherapy for HBV; peg-IFN, entecavir, or tenofovir
  • Interferons are effective at suppressing viral replication, although require an injection; IFN-α & lamivudine approved for treatment in children
    • Interferon: thought to inhibit viral replication & cell proliferation through modulation of complex cell signals trigged by the molecule binding to cell surface
    • Monitoring: CBC, LFTs monthly; HBV DNA levels & TSH Q24wk
  • Nucleoside reverse transcriptase inhibitors–inhibit viral replication by blocking reverse transcriptase resulting in inhibition of viral DNA synthesis
    • PO dosing: may be preferable over IFN therapy (injection)
    • Lamivudine → selection for resistance associated with long treatment duration & ↑ HBV DNA levels; 20% resistance 1st year & 70% at 5th year; patients with breakthrough infection should be tested for lamivudine resistance → if resistance confirmed, use a treatment regimen effective against lamivudine-resistant viral strains
      • Add adefovir or tenofovir ...

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