Hepatitis A Virus - HAV

Diagnostic Algorithm

  Hepatitis Virus Screening Algorithm

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
  • <3,000 cases per year in the U.S. (CDC statistics for 2007)
  • 50-70% of U.S. adults have antibodies
• Age – more prevalent among day-care and school-aged children
• Transmission
  • Fecal-oral via person-to-person contact
  • Ingestion of contaminated food or water
  • Occurs sporadically or in epidemics

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

Diagnosis

Indications for Testing

• New onset of jaundice, anorexia or dark urine
• Known exposure to HAV

Laboratory Testing

• Initial testing (nonspecific)
  • CBC
  • Transaminases – usually markedly elevated
  • Screening for acute hepatitis
    • Hepatitis acute panel test includes HAV, hepatitis B (HBV) and hepatitis C (HCV)
• HAV IgM antibodies generally appear 4 weeks after infection
  • May persist up to 4 months after onset of clinical symptoms
• Total HAV antibodies (IgM and IgG) indicate past infection or immunization; presence associated with immunity

Differential Diagnosis

• Viral
  • Cytomegalovirus
  • Epstein-Barr virus
  • Herpes simplex virus
  • Varicella-zoster virus
  • Hepatitis B, C, D or E 
• Toxin exposure
  • Alcohol
  • Tetrachloride
• Nonalcoholic acute steatohepatitis
• Drug-induced hepatitis
  • Acetaminophen
  • Antiseizure medications
  • Isoniazid (Nydrazid)
  • Oral contraceptives
  • Rifampin (Rifadin)
  • Sulfonamides
• Autoimmune disease
  • Systemic lupus erythematosus
  • Primary biliary cirrhosis
  • Sclerosing cholangitis
  • Autoimmune hepatitis
• Bacterial infection
  • Leptospirosis
  • Q-fever (Coxiella burnetii)
  • Rocky Mountain spotted fever (Rickettsia rickettsii)
  • Secondary syphilis (Treponema pallidum)
  • Sepsis
  • Typhoid fever (Rickettsia typhus) 
• Granulomatous
  • Mycobacterium tuberculosis
  • Sarcoidosis
• Hereditary
  • Wilson disease
  • Hemochromatosis
  • Alpha-1-antitrypsin deficiency
• Ischemic
• Parasitic
  • Liver trematodes
  • Toxocariasis

Indications for Laboratory Testing

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory

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Test Name and Number	Comments
Hepatitis A Virus Panel 0020597 Method: Chemiluminescent Immunoassay