Importance of Avidity IgG for differentiation of Acute Toxoplasma gondi infection

Toxoplasmosis has been well known as an important human infection to consider especially in pregnant women. Although many serologic methods are available, the diagnosis of early toxoplasmosis can be extremely difficult. The aim of this study is detecting Toxoplasma IgG antibodies developed at early stage of infection in pregnant women. 225 pregnant womens who were in 2-4 months of their pregnancy, enrolled in this study. They were categorized into three groups. Anti toxoplasma IgG, IgM and IgG Avidity were evaluated by ELISA method. Group A: 124 case (IgG+, IgM+) (55.1 percent), group B: 99 case (44percent)(IgG+,IgM-), and group C: 2 case (0.9 percent)(IgG -, IgM +). Fifty five percent of the pregnant women had positive IgG and IgM among whom 7.1 percent had low avidity that reveals the active infection in the pregnant women.In the current study 44 percent of the pregnant women had positive IgG and negative IgM that all had high avidity which indicates that in our society the level of toxoplasma infection is high and women have contact with this parasite before pregnancy. In this study the low avidity was 7.1 percent which shows that in different societies, the occurrence of toxoplasma infection is still a serious issue. Observation of 45.8 percent high avidity among group A suggests that either IgM has a high half-life or the false existence of IgM in Rheumatologic disorders makes it positive falsely. Therefore, avidity test has a high value and by a timely differential diagnosis of active toxoplasma infection, it would be cured.