Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 14 4 2019 12 31 639 645 EN Karam SHARIFI Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Bibi Razieh HOSSEINI FARASH Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran AND Research Center of Skin Diseases and Cutaneous Leishmaniasis, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Fatemeh TARA Department of Obstetrics and Gynecology, Mashhad University of Medical Sciences, Mashhad, Iran Azad KHALEDI Infectious Diseases Research Center, Department of Microbiology and Immunology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran AND Department of Microbiology and Immunology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran Karim SHARIFI Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Seyed Ali Akbar SHAMSIAN Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran AND Iranian Academic Center for Education, Culture, and Research (ACECR), Mashhad, Iran 2017 12 30 2019 12 31 Background: We aimed to evaluate the diagnosis of acute toxoplasmosis by IgG avidity test in pregnant women. Methods: In this cross-sectional study, 250 blood samples were collected from pregnant women with the first month of their pregnancy referring to health centers of University in Mashhad during 2016. Samples were centrifuged at 3000 rpm for 5 min for separation of serum and were kept in the -20 until use. To detection of acute and chronic toxoplasmosis, anti-Toxoplasma antibodies (IgG and IgM, and IgG avidity tests were performed using ELISA. Then, data analyzed using SPSS software by Frequency, Pearson Chi-Square, Likelihood Ratio, and Exact tests. And P<0.05 was statistically considered as significant. Results: Total prevalence of IgG and IgM was 23.2% and 7.2%, respectively. A significant correlation was observed between the mean age and IgG level (P<0.05). It was not found any correlation between the history of raw meat consumption, cats keeping, education, and residency site. Moreover, 16 people (6.4%) had IgM antibody, of which, 10 cases (62.5%) with low avidity for IgG and 1 people (6.2%) with moderate avidity and 5 cases (31.3%) with high avidity for IgG. Moreover, 76% of pregnant women were seronegative. Conclusion: More than half of the women (62.5%) with positive IgM antibody in their serum had a low avidity for IgG which revealed an acute infection among pregnant women. Toxoplasma infection should be considered as an important factor that affects the pregnancy and IgG avidity as an important test for screening the women who need the treatment. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/1944