Contribution of IgG avidity and PCR for the early diagnosis of toxoplasmosis  in pregnant women from the North-Eastern region of Algeria.

Hajira Berredjem, Hayette Aouras, Meriem Benlaifa, Imène Becheker, Mohamed Reda Djebar

1. Department of Biochemistry, Faculty of Sciences, University of Badji Mokhtar, Annaba, Algeria
2. Laboratory of Cellular Toxicology, Faculty of Sciences, University of Badji Mokhtar, Annaba, Algeria
3. Service of Gynecology, EHS Abdallah Nouaouria Hospital, El Bouni-Annaba, Algeria

Abstract:
Background: Acute toxoplasmosis in pregnant women presents a high risk of Toxoplasmatransmission 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-ToxoplasmaIgG, 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 ToxoplasmaDNA 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.

Keywords: Toxoplasmosis, pregnant women, serology, IgG avidity, PCR.