IgG avidity and placenta real-time PCR in detection of active maternal toxoplasmosis: relation to pregnancy outcomes

Toxoplasmosis diagnosis during pregnancy is important for the management of pregnant women suspected to have early T. gondii infection. This study aimed to detect T. gondii infection using ELISA and placenta real-time PCR among pregnant women. The study involved 149 women from El Shatby Hospital, Alexandria University; 50 experienced spontaneous abortion and 99 delivered normally, among whom four cases were spiramycin treated. Only 83 women agreed to submit blood samples that were ELISA tested for Toxoplasma IgG and IgM antibodies (ELISA Biokit, Barcelona, Spain). ELISA IgG positives were re-examined for IgG avidity. Placental samples were collected from all participants (about 20 g from each), and DNA was extracted using the Qiagen DNA kit, Hilden, Germany. The samples were examined by real-time PCR targeting the REP-529 gene. Out of the 83 women, 57 (68.7 %) were IgG positive and only one case was IgM positive. Fifty IgG cases had low IgG avidity and seven had high IgG avidity. Approximately one-third of the 149 placenta samples, 83 serologically examined cases, 57 IgG positives; 50 with low avidity, and 7 with high avidity, tested positive by real-time PCR, with detection rates of 29.5 %, 28.9 %, 31.5 %, 32 %, and 28.6 %, respectively. Moreover, it detected six positives among the IgG negatives, and two of the four spiramycin-treated cases tested positive. No significant difference between abortion and normal delivery rates was observed among T. gondii positive and negative women, either by ELISA IgG and/or real-time PCR. In conclusion, combining IgG avidity and placenta real-time PCR is promising for detecting T. gondii active infection and the probability of fetal infection.