Hepatitis A Virus - HAV

 

Clinical Background

The targeted use of the Hepatitis A (HAV) vaccine in the U.S. since 1995 has led to a dramatic decrease in the number of reported cases of Hepatitis A.

Epidemiology

  • Incidence
    • >7,000 cases per year in the U.S.
    • 50-70% of U.S. adults have antibodies
  • Transmission
    • Fecal-oral via person-to-person contact
    • Ingestion of contaminated food or water
    • Occurs sporadically or in epidemics
  • Age – more prevalent among day-care and school-aged children

Organism

  • Nonenveloped RNA picornavirus
  • Infects only primates
  • Virus survives for extended periods in seawater, fresh water, waste water and soil
  • Resistant to freezing, detergents and acids
  • Lack of lipid envelope confers resistance to bile lysis
  • Virus infects the hepatocytes, no propensity for chronic infection

Risk Factors

  • Raw seafood
  • Infected food handlers
  • Day-care settings

Clinical Presentation

  • Usually asymptomatic or with mild symptoms (fever, nausea, malaise) after incubation period of about 28 days
  • Jaundice, dark urine, abdominal pain
  • Physical symptoms – hepatomegaly, splenomegaly, bradycardia, lymphadenopathy
  • Complications
    • Encephalopathy and fulminant liver failure in patients with immunosuppression or multiple comorbidities (eg, chronic liver or renal disease)
    • No chronic state
    • Gastrointestinal – acalculous cholecystitis, pancreatitis
    • Hematologic – aplastic anemia, hemolytic anemia, thrombocytopenic purpura, red cell aplasia
    • Neurologic – Guillain-Barré syndrome, mononeuritis, transverse myelitis
    • Renal – acute tubular necrosis, interstitial nephritis, glomerulonephritis
    • Other – cutaneous vasculitis, cryoglobulinemia, reactive arthritis

Treatment

  • Supportive

Prevention

  • Vaccination prior to school entry