Diagnosis of acute toxoplasmosis in pregnant women referred to therapeutic centers of Alborz Province (Iran) using immunoglobulin G avidity ELISA technique

Objective: To evaluate immunoglobulin G (IgG) avidity as a useful and reliable technique in diagnosing toxoplasmosis in pregnant women referring to therapeutic centers of Alborz Province (Iran) in 2014, against two other tests, IgG and immunoglobulin G (IgM) antiToxoplasma. Methods: Serum samples (468 in total) were obtained from different therapeutic centers in Karaj City. ELISA method was used to test the anti-Toxoplasma avidity of IgG, IgM and IgG. The data were analyzed by descriptive statistical methods and Chi-square test (P < 0.05) using SPSS 17.0. Results: Anti-Toxoplasma tests of IgM and IgG were positive in 9 and 86 samples respectively. Also, a borderline IgM was detected in 2 suspected samples. In addition, among all positive and suspected samples, 79 cases indicated high titers of IgG avidity, 7 cases were of low titers and 1 case was of a borderline titer. The prevalence of anti-Toxoplasma antibodies was 20%. The sera which showed high avidity index was obtained from patients at chronic phase of infection (92%) while those which showed low avidity levels were from patients at acute toxoplasmosis (77.7%). Conclusions: This study clearly showed that acute and chronic phases of toxoplasmosis could be differentiated with the aid of IgG avidity test. This test may also assist in recognizing old and newly acquired infections.