Hepatitis A Virus - HAV

  • Diagnosis
  • Algorithms
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • New onset of jaundice, anorexia, dark urine
  • Known exposure to hepatitis A virus (HAV)

Laboratory Testing

  • Hepatitis A information for health professionals (CDC)
  • Initial testing (nonspecific)
    • CBC – usually normal
    • Transaminases – usually markedly elevated
  • Testing for acute hepatitis
  • HAV IgM antibodies
    • Diagnose acute HAV infection if exposure is suspected or documented
    • Antibodies generally appear 4 weeks after infection (~5 days before symptoms)
    • May persist up to 6 months after onset of clinical symptoms
  • Total HAV antibodies (IgM and IgG) indicate past infection or immunization – presence associated with immunity
    • Assess immunity for HAV from vaccination or previous infection
    • IgG does not appear until convalescent phase but remains detectable for life

Differential Diagnosis

The targeted use of the hepatitis A (HAV) vaccine in the U.S. since 1995 has led to a 92% decrease in the number of reported cases of HAV.

Epidemiology

  • Incidence
    • Most common cause of viral hepatitis worldwide
    • Incidence – 1/100,000
      • 2,000 cases in the U.S. in 2009 (CDC)
    • 50-70% of U.S. adults have antibodies
  • Age – more prevalent among day-care and school-aged children
  • Transmission
    • Fecal-oral (unlike hepatitis B or C)
    • Ingestion of contaminated food or water
    • Occurs sporadically or in epidemics
    • Virus only viable on fomites, including produce, for about 1 week
    • Viral shedding in the stool lasts up to 6 months, but the period of contagiousness highest during the two weeks prior to onset of jaundice

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

  • In the U.S., 70% of patients have no specific risk factors
  • Raw seafood
  • Infected food handlers
  • Day-care settings
  • International travel – accounts for ~50% of cases

Clinical Presentation

  • Usually asymptomatic or with mild symptoms (fever, nausea, malaise) after incubation period of ~28 days
    • Symptoms last an average of 2 months
  • Jaundice, dark urine, abdominal pain, elevated transaminase levels, anorexia
  • Physical symptoms – hepatomegaly, splenomegaly, bradycardia, lymphadenopathy
  • No chronic hepatitis sequelae
  • Complications – range from asymptomatic to acute, debilitating disease
  • Case fatality rate for HAV infection is 0.3-0.6% but may be as high as 1.8% among persons >50 years
  • More likely to result in significant liver disease with coinfection of HBV or HCV or in pregnant women
    • HAV may be prolonged with HIV coinfection

Treatment

  • Supportive

Prevention

  • Universal vaccination against HAV recommended for the following
    • Children 1-18 years
    • High-risk groups, including men who have sex with men, drug abusers, and people who frequently travel to countries endemic for the virus
    • Strong immunity results even from relatively low vaccination rates
  • Vaccination prior to school entry or travel to endemic areas
    • After vaccination, immunity is active within ~1 week and therefore useful as post-exposure prophylaxis if given within 2 weeks of exposure
      • Useful in community outbreak
  • Intramuscular IgG from pooled human plasma after exposure provides passive protection for ~6 months

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.

Hepatic Function Panel 0020416
Method: Quantitative Enzymatic/Quantitative Spectrophotometry

CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Hepatitis Panel, Acute with Reflex to HBsAg Confirmation 0020457
Method: Qualitative Chemiluminescent Immunoassay

Hepatitis A Virus Antibodies (Total) 0020591
Method: Qualitative Chemiluminescent Immunoassay

Limitations

Total assay detects both IgG and IgM antibodies but does not differentiate between them

Hepatitis A Virus Antibody, IgM 0020093
Method: Qualitative Chemiluminescent Immunoassay

Limitations

False-positive rates are high with more than 60% of positive HAV IgM antibody results reported on patients who do not meet clinical criteria 

Related Tests

General References

Andersson KL, Friedman LS. Hepatitis a: a traveling target; comment on "the evolving epidemiology of hepatitis a in the United States". Arch Intern Med. 2010; 170(20): 1818-9. PubMed

Jeong S, Lee H. Hepatitis A: clinical manifestations and management. Intervirology. 2010; 53(1): 15-9. PubMed

Kojaoghlanian T, Kojaoglanian T. Hepatitis A. Pediatr Rev. 2010; 31(8): 348-50. PubMed

Matheny SC, Kingery JE. Hepatitis A. Am Fam Physician. 2012; 86(11): 1027-34; quiz 1010-2. PubMed

Nainan OV, Xia G, Vaughan G, Margolis HS. Diagnosis of hepatitis a virus infection: a molecular approach. Clin Microbiol Rev. 2006; 19(1): 63-79. PubMed

Sharapov UM, Hu DJ. Viral hepatitis A, B, and C: grown-up issues. Adolesc Med State Art Rev. 2010; 21(2): 265-86, ix. PubMed

Medical Reviewers

Last Update: April 2016