RESUMEN
The present study describes the performance of two commercial enzyme immunoassays (EIAs) employing recombinant capsid proteins derived from baculovirus or from yeast for diagnosis of human parvovirus B19 (B19) infection. At first, 450 sera from routine daily practice submitted consecutively for B19 antibody testing during a 2-week period in March 2006 were tested. Eighty percent of the routine sera were from pregnant women. There was a high degree of accordance between the two assay systems in detection of B19 IgG antibodies (98.9%) and B19 IgM antibodies (98.7%). Specific antibody concentrations of serum specimens with discordant test results (n=11) were within or close to the equivocal range of the respective assay. Subsequently, specificity and sensitivity of the IgM EIAs were assessed in detail by testing 160 sera collected from patients with a defined disease state. Specificity ranged between 94.2 and 98.5% in patients (n=70) with other acute infections or autoimmune diseases. In sera from pregnant women (n=30) and children (n=30) with acute B19 infection, both assays were 100% sensitive. Whereas sensitivity varied from 63.0 to 70.0% in pregnant women (n=30) investigated 8-12 weeks after onset of disease. According to our evaluation the diagnostic performance of the two assay systems appears to be substantially equivalent. Fetal hydrops is sometimes a late complication of gestational B19 infection and maternal B19 IgM antibodies may already have declined to undetectable levels at the time of clinical diagnosis. A negative B19 IgM test during pregnancy should therefore be interpreted with caution.