Usefulness of specific IgG avidity for diagnosis of hepatitis A infection.
OBJECTIVE
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.


CONCLUSIONS
This test could improve the diagnosis of acute hepatitis A infection, particularly in elderly patients.
Centre National de Référence pour les virus à transmission entérique, Laboratoire de Virologie, Hôpital Paul Brousse, Villejuif.
Delphine
D
Desbois
Liliane
L
Grangeot-Keros
Bénédicte
B
Roquebert
Anne-Marie
AM
Roque-Afonso
Vincent
V
Mackiewicz
Jean-Dominique
JD
Poveda
Elisabeth
E
Dussaix
D000293:Adolescent; D000328:Adult; D000368:Aged; D000915:Antibody Affinity; D016022:Case-Control Studies; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006506:Hepatitis A / Q000175:diagnosis* / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012698:Serologic Tests
D007074:Immunoglobulin G