الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
T. gondii is an obligate intracellular coccidian protozoan parasite that may infect and proliferate in humans, birds, and all warm-blooded animals worldwide. It is estimated to infect about one-third of the world’s population. It is one of the top 10 opportunistic pathogens and the fourth-deadliest pathogen in immunosuppressed individuals. T. gondii has three
infectious stages; the acute tachyzoite stage, which is accountable for the mother-fetal pass;
the dormant life-persistent tissue cyst containing bradyzoites, which mainly forms in neural
and muscular tissue, in placenta and uterus; and the environmental oocysts, which exclusively
develop in the feline gut and spread throughout their manure.
The diagnosis of infection is based on serological testing that looks for particular antibodies such as anti-T. gondii IgG and IgM. Other methods are proved to be of great value towards toxoplasmosis among pregnant women. Of these methods are; the serum IgG avidity test, PCR on tissues (placenta) and body fluids and Western blots on mother-baby serum. Till now few studies were conducted on the toxoplasmosis diagnosis in pregnant women in Egypt, so the present study aimed to diagnose T. gondii infection among pregnant women (spontaneously aborted and normally delivered), real-time PCR was performed in the placenta.
The present work is a cross-sectional study that was conducted on 149 pregnant women admitted in EL Shatby Hospital either for delivery or spontaneous abortion. They were randomly selected, and their informed consents for study participation were obtained. Their
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age ranged from 17 to 43 years, with a mean age of 26.9 ± 6.7 years. The majority of participants (52%) were under the age of 26, and the lowest percentage (17%) belonged to the 35–43 years. Regarding pregnancy outcomes, 33.5% of women experienced spontaneous abortions, 63.8% of women delivered normally, and 2.7% of women received spiramycin and gave birth normally.
Out of the 149 participants, 83 women agreed to submit blood samples. About 3 ml of venous blood were drawn and transported to the laboratory of Parasitology Department, Medical Research Institute. Clear and non-hemolyzed sera were collected after centrifugation. About 20 g of the placenta sample was collected from each participating woman and cut into small pieces under sterilized conditions. Serum and placenta samples were stored at -20˚C until use. All collected sera were examined for T. gondii by IgG and IgM. Positive IgG were tested for IgG avidity. All placenta samples were tested by real-time PCR.
The obtained results showed that the IgG seroprevalence was 68.7%, which denotes that participants had previously been infected with T. gondii. On the other hand, 31.3% of the individuals were seronegative, suggesting that they may be vulnerable to primary infection during the subsequent pregnancy. Acute toxoplasmosis was suspected in 1.2% of the women who tested positive for IgM antibodies.
As for auxiliary IgG avidity, among the 57 women who tested positive for IgG, 50 (87.7%) had low IgG avidity, and 7 (12.3%) had high IgG avidity, indicating acute and chronic toxoplasmosis, respectively.
Regarding molecular technique, the current study employed real-time PCR to detect T. gondii in mothers’ placentas. Of the 149 studied participants, 29.5% of the women’s placentas tested positive for T. gondii. The true prevalence by ELISA and/or real-time PCR was 76 %.
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With special emphasis on abortion, among the 50 aborted women; 34(68%) were positive for IgG including one case of IgM, and 14(28%) women were diagnosed positive by real-time PCR.
The statistical analysis revealed no significant association between real-time PCR and ELISA. At the 95% confidence interval, there was a slight agreement between the two approaches (κ=0.049).
As for the association between avidity and real-time PCR, 32% of the low IgG avidity cases were diagnosed positive by real-time PCR confirming active infection. Two cases of high IgG avidity were positive by real-time PCR which may be because of recurrent infection. Cases with low avidity and negative by real-time PCR may be due to early infection and absence of parasites in the placenta.
Concerning the risk factors, the 63 T. gondii positives by both ELISA and real-time PCR showed no significant association regarding consuming undercooked meat, drinking filtered water, contact with soil, animal contact, cat disease awareness, previous abortion and presence of lymphadenopathy.
In brief, the obtained results revealed that the combination of IgG avidity and real-time PCR performed better than the serological techniques alone. Further studies using IgG avidity and real-time PCR on blood samples and amniotic fluids are warranted for a more comprehensive understanding of the infection dynamics.
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6.2. Conclusion and Recommendations
High prevalence of T. gondii was revealed among pregnant women.
T. gondii may be one of the causes of spontaneous abortion but it is not the only cause.
IgM ELISA test is not reliable for the diagnosis of early acute toxoplasmosis.
Real-time PCR detected active infection in placenta samples among cases of low and high IgG avidity.
Using a combination of IgG avidity and real-time PCR performed better to detect the early T. gondii infection.
Pregnant women positive for T. gondii by IgG ELISA should be treated particularly in low-income countries.
The information concerning positive PCR results in the placenta should appear in the newly born medical records.
The presence of T. gondii among pregnant women highlights the necessity for continuous searching for more accurate diagnostic techniques.
Further studies using IgG avidity and real-time PCR on blood samples and amniotic fluids are recommended.
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