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Contribution of IgG avidity and PCR for the early diagnosis of toxoplasmosis in pregnant women from the North-Eastern
Hajira Berredjem1,2, Hayette Aouras3, Meriem Benlaifa2
1Department of Biochemistry, Faculty of Sciences, University of Badji Mokhtar, Annaba, Algeria.
Background:
Acute toxoplasmosis in pregnant women presents a high risk of Toxoplasma transmission to the fetus. Early diagnosis is difficult, especially when serological testing for IgG/IgM antibodies fail to differentiate between a recent and a past infection. In this case, we rely on IgG avidity or PCR assays.
Objectives:
The aim of this study was to compare conventional ELISA and IgG avidity, with PCR using B1 and P30 primers for the early diagnosis of toxoplasmosis in pregnant women.
Methods:
Sera were collected from 143 pregnant women and measured by ELISA for anti-Toxoplasma IgG, IgM, IgA and IgG avidity. DNA was extracted from 57 peripheral blood and 14 amniotic fluid samples for PCR amplification.
Results:
A total of 57 out 143 women were seropositive: 30 (52.6%) were IgG+/IgM- and 27 (43.8%) were IgG+/IgM+; IgA antibodies were positive in 7 (12.2%) cases. IgG avidity was low in 9 women suggesting an acute infection; 3 women presented an intermediate avidity. PCR detected Toxoplasma DNA in 9 women presenting low avidity and was negative for the intermediate avidity cases.
Conclusion:
PCR combined to avidity IgG performed better than ELISA IgG, IgM and/or IgA assays alone. PCR was useful in the case of intermediate avidity.
