Toxoplasma gondii and Neospora caninum belong to Sarcocystidae family. Life cycles of them are very similar and they are capable to infect a wide range of animals in the world. T. gondii is a main causative of abortion in sheep, while the role of N. caninum infection in causing abortion in sheep is unknown and need more investigation. The aim of study was to compare the rate of T. gondii and N. caninum infection in sheep in Mashhad area. From February to December 2014, 30 head of sheep were monthly purchased from Torghaba abattoir. The sheep skull was opened and brain tissue removed for microscopic and molecular examination. First, Impression smears were prepared from different parts of brain areas and stained with Giemsa staining and brain tissue samples were collected for DNA extraction and bioassay examination. Specific PCR assay was performed to detect T. gondii and N. caninum DNA in brain samples. The brain tissues of PCR-positive samples were bioassayed in the Outbred Swiss Webster and BALB/C mice. The mice were bled and tested for T. gondii or N. caninum antibodies 5 weeks p.i by IFAT. The seropositive mice were also euthanized and then stained impression smears of brain were prepared and microscopically examined for tissue cysts observation. In the present study, the cyst and zoites of T. gondii were not microscopically observed in any stained smears of brain samples of sheep. T. gondii DNA was detected in 13 (43%) brain tissues samples of sheep by nested-PCR. Two groups of inoculated mice developed antibodies against T. gondii and tissue cysts were found in the brain smears of some mice of infected group. N. caninum infection was not detected in any brain samples of sheep by PCR.Our results show that T. gondii infection is common in the sheep of Mashhad area and it seems the N. caninum infection rarely occurs in sheep.

Keywords