Toxoplasmosis caused by the protozoan parasite namely Toxoplasma gondii that infects all of warm- blooded animals and humans. This parasite is transmitted to sheep via ingesting food and water contaminated with oocysts which are excreted by cats or by transmission from mother to fetus (congenital toxoplasmosis). Toxoplasmosis causes reproduction disorders such as fetal resorption, early embryonic death, mummification, abortion, still birth, neonatal and fetal death in sheep. Toxoplasmosis makes significant economic loss due to induction of abortion in sheep and goat worldwide. Various techniques have been applied for diagnosis of abortion caused by toxoplasmosis in infected sheep. In the previous studies, the diagnosis of T. gondii infection was usually based on serological assay, histopathological examination, and isolation of Toxoplasma by mouse inoculation while in the recent studies molecular methods are used. The aim of this study was to determine the frequency of Toxoplasma infection in aborted ovine fetuses in the province using molecular methods. 112 brain samples of aborted fetuses of sheep were collected from 2009 to 2014 and were examined to detect Toxoplasma gondii infection by the Nested-PCR technique. Result: The result showed that 18 out of 112 (16.07%) ovine fetuses‟ brain samples were PCR-positive based on the Nested PCR. In this study, a significant difference was found between Toxoplasma infections in two different area of Khorasan province (≤P0.05).DNA detection of Toxoplasma gondii by molecular methods is more sensitive than other methods. Isolation and detection DNA of Toxoplasma gondii in aborted fetuses of sheep shows that this parasite is important in abortion. The most positive samples were detected in aborted fetuses in the north areas of Khorasan Razavi province which have more humidity than the south areas with dry climate. Higher prevalence rate of toxoplasmosis in moist areas compared arid areas is related to the longer viability of T. gondii oocysts in moist. The results of our study show that congenital toxoplasmosis in sheep is extremely important because infected sheep play an important role as source of human infection.

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