Abstract
BACKGROUND: Toxoplasmosis and neosporosis are important protozoan infections affecting sheep production in Türkiye, with implications for both animal health and zoonotic risk. In light of their epidemiological relevance, the present study aimed to investigate the seroprevalence and endemic status of Toxoplasma gondii and Neospora caninum infections in the sheep population across Türkiye. METHODS: A total of 2,688 sheep serum samples randomly collected from the seven geographical regions of the country were analyzed using an indirect ELISA based on recombinant TgSAG2 and NcSAG1 proteins. RESULTS: According to the results, the overall seroprevalence was 30.51% for T. gondii and 5.21% for N. caninum. The highest T. gondii seropositivity was in the Black Sea Region (38.54%), and the lowest in Central Anatolia (19.27%) and the Mediterranean Region (21.35%). For N. caninum, the highest seroprevalence was also in the Black Sea Region (11.46%), and the lowest in the Aegean Region (2.60%). Mono-infections with T. gondii and N. caninum were 27.01% and 1.71%, respectively, while 3.50% of the animals were co-infected. T. gondii seropositivity was significantly higher in sheep over 12 months of age (33.92%) than in younger animals (18.41%) (P < 0.001), whereas no age-related association was found for N. caninum (P = 0.485). Regional differences were significant for both pathogens (P < 0.001). Although higher seropositivity rates were observed in rural areas for both infections, the differences were not statistically significant (T. gondii: P = 0.318; N. caninum: P = 0.0777). Inoculation rates revealed endemic instability for both toxoplasmosis and neosporosis across all age groups, indicating a risk of uncontrolled spread and potential for periodic outbreaks. CONCLUSION: In conclusion, T. gondii was found to be widespread among sheep in Türkiye, whereas N. caninum had a more limited yet notable distribution. Given the zoonotic importance of toxoplasmosis, it is crucial to strengthen biosecurity and implement region-specific, risk-based control strategies. This study lays a scientific foundation for future preventive measures by enabling nationwide epidemiological mapping of ovine toxoplasmosis and neosporosis.