Raeghi et al.: Seroprevalence of Toxoplasma gondii in Sheep … Introduction Tzoonotic disease caused by the oxoplasmosis is a cosmopolitan obligatory protozoan Toxoplasma gondii being responsible for major economic losses in most classes of livestock through abortions, still birth and neonatal losses (1,2). The distribution of this parasite depends on regions and weather condition where the oo- cysts survive in environment (3-5). The ingestion of undercooked infected meat is considered as an important source of the infection for humans (6,7). Despite its worldwide presence, the preva- lence of toxoplasmosis is not well known especially In Urmia. Urmia is located in northwest of Iran (37°33′N 45°06′E / 37.55°N 45.1°E) with semi-humid climate and moderately cold winters. The present study is the first report that aimed at determining the prevalence of T. gondii infection in sheep, cattle and horses in this region. Materials and Methods Blood samples were collected from 156 sheep, 120 cattle and 26 horses that were brought to Urmia University veterinary hos- pital only for surgery occurred from accident from July 2009 till April 2010. Sera of sam- ples were separated and stored at −20°C un- til assayed. Specific IgG antibodies to T. gondii were examined with Modified agglutination test (MAT) as described by 91 Desmonts (8). Toxoplasma RH strain tachy- zoites supplied by Department of Parasitol- ogy at Kerman University of Medical Sci- ences, Iran, were propagated in mice and cell culture, isolated and fixed in formaldehyde solution (9). Sera were tested on 96-well plates with a U shaped bottoms (25 µl of prepared mix antigen plus 25 µl of serum), based on two-fold serial dilutions, from 1:10 until 1:160 beside of negative and positive controls and antibody titer of ≥1:20 was con- sidered positive (10,11). Positive controls supplied by Veterinary Faculty of Urmia University, Iran. The data were analyzed by the Chi-square, Fisher's Exact and Cochran’s and Mantel-Haenszel Tests. The level of sig- nificance was set at P< 0.05. Results Thirty-three (21.1%) sheep, 2 (1.6%) cattle and 3(11.5%) horses were seropositive to T. gondii by MAT. The data of T. gondii anti- bodies and MAT titers in all groups of ani- mals are shown in Table 1. Univariate analy- sis showed that sheep are 15 times more likely to be seropositive than cattle (OR=15.829; 95% CI=3.715-67.445), also analysis showed that sheep are 2 times more likely to be seropositive than horses (OR=2.057; 95% CI=0.582-7.273). This study showed that horses are 7 times more likely to be seropositive than cattle (OR=7.696; 95% CI=1.217- 48.656).