الفهرس 
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Abstract
Serologic testing for toxoplasmosis using the cocktail triad of IgM, IgG and IgG avidity ELISA tests was performed on sera from 246 primigravidae who had completed a multi-stage serum sampling schedule. Eighty three cases were diagnosed as gestational toxoplasmosis, of whom 19 cases diagnosed on the basis of sero-conversion, and 64 cases on the basis of low avidity IgG and /or positive IgM. Fifty four cases were diagnosed as preconceptional toxoplasmosis on the basis of high avidity IgG; and in 109 cases no antibodies were detected.
Toxoplasma parasites were isolated by mouse-inoculation from 75 (90.4%) of 83 serologically diagnosed gestational infection, and from non of the other groups.
Toxoplasma genomic DNA could be amplified from 74 (89.1%) and 72 (86.74%) of 75 Toxoplasma- positive sera using primers targeting the multi-copy 18Sr DNA and the single copy (SAGI) genes respectively. Taking mouse-inoculation as the gold standard, the polymerase chain reaction using the 18Sr DNA gene as a target and in comparison to serologic testing proved less sensitive, but more specific and more accurate. No false- positive reactions were recorded by the PCR- technique comparable to 9.63% by serologic testing meanwhile, 4% false- negative results were recorded by the PCR- technique. The single copy P30 (SAGI) gene, as a target proved less sensitive and less accurate than the multi-copy 18Sr DNA gene. Both mouse- inoculation and PCR studies emphasized the importance of reliance on high avidity IgG results in excluding gestational toxoplasmosis, and the necessity for serologic and echographic surveillance for PCR-negative cases due to the low predictive value of the PCR- technique.
As a test, the PCR- technique eliminates the possibility of false- positive reactions in serologic testing, it can predict the time of infection, and it avoids the short shelf- span of antibody detection kits, since the oligonucleatide primers can be stored for a long time.