APPRAISAL OF PRENATAL ANTI-TOXOPLASMA GONDII (IGG+IGM)- IHA/IGM-ELISA SCREENING IN SINGLE SAMPLES VIA IGG AVIDITY TEST

Document Type : Original Article

Authors

1 Faculty of Medicine, PO Box 715, Umm Al-Qura University, Makkah, Saudi Arabia.

2 Al-Noor Specialist Hospital, Makkah, Saudi Arabia.+

3 Department of Parasitology, Faculty of Medicine, Assuit University, Assuit, Egypt.

4 Al-Noor Specialist Hospital, Makkah, Saudi Arabia.

Abstract

Congenital toxoplasmosis is associated with important morbidity and mortality. Since vertical transmission of Toxoplasma gondii can occur in acute cases, antenatal screening for recent infections is vital. Accurate determination of acute toxoplasmosis requires a combination of immunoassays, usually not routinely applied for screening purposes. This study evaluated the anti-T. gondii (IgG+IgM)/IgM prenatal screening procedure by IgG avidity assay. The routine prenatal screening for (IgG+IgM) anti-T. gondii by indirect hemagglutination (IHA) in serum samples was done of 2247 pregnant women who attended two hospitals between 2011 and 2013 revealed 487 (21.7%) positive samples. Examination
of IHA-positive sera by IgM and IgG/IgG-avidity concurrent ELISA tests revealed 7 positive and 3 border-line IgM-ELISA titers during the initial check-up of 10 women, who were then followed up at 3-4 week-intervals. Among these, 4 (40%) showed simultaneous high avidity IgG antibodies, indicating distant infection by the parasite, and no anti-T. gondii specific IgG could be detected in follow-up sera of two cases (20%), indicating false IgM initial positive results. Only 4 (40%) women showed simultaneous IgM and low avidity IgG antibodies indicating active infections. Avoidance of an overdiagnosis of acute toxoplasmosis Anti-T. gondii (IgG+IgM)/IgM prenatal screening must be supplemented by a discriminative test like IgG avidity ELISA.

Keywords

Journal of the Egyptian Society of Parasitology
Volume 46, Issue 1
April 2016
Pages 201-208

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