Gastroenterology Book

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Hepatitis A

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  1. See Also
    1. Viral Hepatitis
  2. Epidemiology
    1. Endemic in underdeveloped countries
    2. More common in western United States
    3. Outbreaks
      1. Day-care centers
      2. Residential institutions
    4. Incidence U.S.: 60,000/year (only 7700 reported)
  3. Pathophysiology
    1. Picornavirus (enterovirus)
      1. Single stranded RNA genome
      2. Size: 27 nm
      3. Nonenveloped (resistant to bile lysis)
      4. Only replicates in hepatocytes, GI epithelial cells
    2. Hardy agent
      1. Resistant to acids, detergents, freezing temperatures
      2. Survives in salt water and fresh water, soil, hands
      3. Inactivated by heat >185 F, formalin, Chlorine
  4. Pathophysiology: Timing
    1. Incubation 15 to 45 days (median 30 days)
    2. Contagious status
      1. Stool virus conc. peaks 2 weeks before symptoms
        1. Virus replicates in liver and shed by bilary tract
        2. Stool is highly contagious
        3. Transmission most likely in presymptomatic period
        4. Asymptomatic children may shed virus for months
      2. No longer contagious once significant symptoms occur
        1. Jaundice
        2. Liver transaminase elevation
  5. Pathophysiology: Transmission
    1. Oral-Fecal transmission
      1. Household or child care centers
      2. Sexual contact
    2. Foodborne Illness epidemic
      1. Infected food handlers
      2. Raw shellfish
      3. Fresh produce (green onions, strawberries)
    3. Waterborne Illness epidemic
    4. Blood exposure can occur but is uncommon
  6. Symptoms
    1. Symptoms occurence depends on age
      1. Adults: 70% have symptoms
      2. Children under age 6: 70% do not have symptoms
        1. Usually more mild in young children
    2. Common symptoms (onset 5-7 days before Jaundice)
      1. Fever
      2. Severe Anorexia out of proportion with clinical signs
      3. Nausea and Vomiting
      4. Abdominal Pain
      5. Malaise
      6. Headache
    3. Other less common symptoms
      1. Arthralgias
      2. Myalgias
      3. Diarrhea
      4. Cough
      5. Constipation
      6. Pruritus
      7. Urticaria
  7. Signs: 5-7 days before Jaundice
    1. Fever
    2. Enlarged and tender liver (Hepatomegaly)
    3. Splenomegaly
    4. Bradycardia
    5. Posterior cervical adenopathy
  8. Signs and Symptoms: Icteric phase
    1. Pale, clay colored stool
    2. Jaundice (Incidence increases with age)
      1. Under age 6: <10%
      2. Adults: Up to 80%
  9. Course
    1. Illness usually lasts 2 months
    2. Not uncommon to miss 1 month of school or work
    3. Usually complete recovery within 6-12 months
    4. No chronic carrier state
  10. Labs
    1. Complete Blood Count (CBC)
      1. Leukopenia
    2. Liver Transaminases elevated
      1. Alanine Aminotransferase (ALT) elevated
      2. Aspartate Aminotransferase (AST) elevated
    3. Liver Function Tests and Cholestasis Labs elevated
      1. Bilirubin elevated (<10 mg/dl)
      2. Alkaline Phosphatase minimally increased
    4. Hepatitis A Serology
      1. Fecal HAV: present 2-6 weeks after exposure
      2. xHAV IgM
        1. Present 4-12 weeks (up to 6 months) post-exposure
        2. Present 5-10 days before symptom onset
        3. Preferred first-line test (high sensitivity)
          1. Risk of false positive in asymptomatic patients
      3. xHAV IgG
        1. Present from 4 weeks after exposure
        2. Present life-long and confers immunity
  11. Differential Diagnosis
    1. Acute Hepatitis Causes
  12. Management
    1. Symptomatic relief
    2. Rest
    3. Hepatitis A Immunoglobulin
      1. Indicated in severe cases
  13. Prevention
    1. General Hygiene Measures
      1. Meticulous hand washing
      2. See Prevention of Foodborne Illness
    2. Hepatitis A Vaccine for high risk potential exposures
      1. Protective for 20 years or more after 2 doses
      2. Recommended as part of Primary Series for child age 1
    3. Hepatitis A Immunoglobulin
      1. Preexposure for travel within 1 month
      2. Postexposure for close contacts of known case
  14. Complications
    1. Biliary obstruction
    2. Fulminant Hepatitis (rare)
    3. No increased risk of Cirrhosis and liver cancer

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