Usefulness of specific IgG avidity for diagnosis of hepatitis A infection

Gastroenterol Clin Biol. 2005 May;29(5):573-6. doi: 10.1016/s0399-8320(05)82132-3.


Aim: Diagnosis of acute hepatitis A virus (HAV) infection is classically based on the detection of HAV-IgM. Nevertheless, HAV-IgM can be positive for patients with polyclonal stimulation of their immune system (i.e. immune reactivation). To improve the diagnostic yield, an avidity test for HAV-IgG antibodies was developed and tested.

Methods: Avidity tests were performed in 128 sera: 11 selected samples from patients with past infection, 15 acute hepatitis A, 10 vaccinated subjects and 4 patients with immune reactivation as well as 84 HAV-IgM positive unselected sera, provided by routine laboratories.

Results: Patients with past infection had avidities over 70%, whereas avidities in patients with acute hepatitis A were below 50% during the first month following the onset of symptoms. As expected, patients with immune reactivation had avidities over 70% consistent with past infection. The results obtained for the 84 unselected sera allowed reconsidering the diagnosis of acute hepatitis A for nearly a third of patients.

Conclusion: This test could improve the diagnosis of acute hepatitis A infection, particularly in elderly patients.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Antibody Affinity*
  • Case-Control Studies
  • Child
  • Diagnosis, Differential
  • Female
  • Hepatitis A / diagnosis*
  • Hepatitis A / immunology*
  • Humans
  • Immunoglobulin G / analysis
  • Immunoglobulin G / immunology*
  • Male
  • Middle Aged
  • Sensitivity and Specificity
  • Serologic Tests


  • Immunoglobulin G