Iranian J Parasitol: Vol. 6, No.4, 2011, pp.90-94 Table 1: Prevalence of T. gondii antibody and the MAT titers in sheep, cattle and horses in Ur- mia, northwest of Iran Livestock Age No. exam- ined No. (%) posi- tive No. of samples showing the antibody titers at Sheep Cattle Horses ≤6 months 36 >6 months 120 ≤6 months 12 >6 months 108 ≤6 months - >6 months 26 156 120 26 1 32 - 2 - 3 33 (21.1) 2 (1.6) 3 (11.5) Discussion The present study showed a relatively high seroprevalence of T. gondii in sheep in this region of Iran. Few studies have reported T. seroprevalance in livestock in this region. The seropositivity of sheep was 21.1% that is a bit different that of other studies from Iran. For example, a study in Kerman showed that 24.7% of sheep were seroposi- tive to T. gondii using MAT (12). Other stu- dies on seroprevalence in sheep in center (13) and southwest (14) of Iran showed the seropositivity of 29.1% and 13.1%, respec- tively in these two regions. The seroprevalence of T. gondii antibodies in cattle was 1.4%. Higher rates of seropositivity of the infection were reported from other regions of the world, i.e. 10.5% in Vietnam (15), 9% in Indonesia (16) and 0% in another part of Iran (17). In our study, the seropositive sheep were 15 times more than the seropositive cattle. It seems that different susceptibility to T. gondii infection in different animal species is important in consequent infections. A study in Mazanda- ran Province (north of Iran) found no T. gon- dii seropositivity in cattle (18), but Hamidinejat showed that 15.7% of cattle were seropositive in south-west of Iran by MAT (19). 92 1:20 1 16 1 1:40 1:80 8 1 4 3 1:160 4 Our study showed that seropositivity in horses was 11.5%. This is first report on the seroprevalence of equine T. gondii infection from Urmia. A similar study in Qazvin, Iran, showed a quite higher rate of seropositivity (71.2%) in horses (20). Existence of Toxop- lasma infection in horses may depend on sta- ble conditions. The seroprevalence differ- ences can be attributed to epidemiological factors effective on T. gondii parasite. It can be noted that sampling techniques, husban- dry method used in different regions, fre- quency of cats on the farms and climatic variations from one region to another, which are essential elements in epidemiological studies and different results. In conclusion, the present study showed seroprevalence of T. gondii infection in live- stock with a considerable rate in sheep in Urmia, northwest of Iran. The infection in sheep and cattle in this region of Iran can be a good reason for further characterization and control of T. gondii infection in animals towards the reduction of human infection.