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Departments of
1
Clinical Biochemistry and
2 Mycobacteriology and Parasitology, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark.
aAuthor for correspondence. Fax 45-3268-3878; e-mail bnp{at}ssi.dk.
Background: To screen for congenital toxoplasmosis, we developed a time-resolved immunofluorometric assay for the simultaneous detection of Toxoplasma gondii-specific IgM and IgA in filter-paper samples collected from newborns 47 days after birth.
Methods: The assay was performed on the AutoDELFIATM, and results were calculated based on the ToxoM WHO Third International Reference Serum. Comparison with an in-house µ-capture immunoassay was carried out retrospectively on filter-paper samples from children with confirmed congenital toxoplasmosis. Prospectively the assay was compared with a µ-capture immunoassay on 68 394 samples and a commercially available assay on another 69 467 samples. Before serum was requested from the newborn, positive samples were tested for IgA and IgM separately and in an IgM-immunosorbent agglutination assay developed for filter-paper samples.
Results: Intra- and interassay variations (CVs) were 8% and 16%, respectively. The cutoff of 5 units/mL produced a 0.5% retest rate. The assay detected 13 of 18 (72%) samples from newborns diagnosed with congenital toxoplasmosis in the retrospective study. Prospectively, the assay identified 24 newborns who were later diagnosed with congenital toxoplasmosis. Results for all 24 cases were positive by the respective comparison method. No cases were detected solely by the IgA antibodies in the sample.
Conclusion: Neonatal screening for congenital toxoplasmosis can be automated by use of purified europium-labeled antigen for detection of T. gondii-specific IgM and IgA eluted from filter-paper samples.
The following articles in journals at HighWire Press have cited this article:
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H.-K. Tan, E. Petersen, L. N. Moller, P. Phillips, E. C. Neto, and R. E. Gilbert Recovery of Anti-Toxoplasma gondii Immunoglobulin M in Stored Guthrie Card Blood Spots J. Clin. Microbiol., August 1, 2009; 47(8): 2626 - 2628. [Abstract] [Full Text] [PDF] |
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D R Schmidt, B Hogh, O Andersen, J Fuchs, H Fledelius, and E Petersen The national neonatal screening programme for congenital toxoplasmosis in Denmark: results from the initial four years, 1999-2002. Arch. Dis. Child., August 1, 2006; 91(8): 661 - 665. [Abstract] [Full Text] [PDF] |
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H. V. Nielsen, D. R. Schmidt, and E. Petersen Diagnosis of Congenital Toxoplasmosis by Two-Dimensional Immunoblot Differentiation of Mother and Child Immunoglobulin G Profiles J. Clin. Microbiol., February 1, 2005; 43(2): 711 - 715. [Abstract] [Full Text] [PDF] |
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