First serological evidence and risk factor analysis of Neospora caninum and Besnoitia besnoiti infections in cattle and sheep from three regions of Saudi Arabia.

Background and Aim: Protozoan infections such as Neospora caninum and Besnoitia besnoiti are significant causes of infertility, abortion, and productivity losses in livestock. Despite their economic impact, epidemiological data from the Kingdom of Saudi Arabia (KSA) remain scarce. This study aimed to determine the seroprevalence of N. caninum and B. besnoiti in cattle and sheep across Asir, Jeddah, and Al-Qassim regions of KSA and to assess the influence of potential risk factors, including species, sex, age, breed, season, and management system. Materials and Methods: A cross-sectional study was conducted between June 2024 and March 2025 using 920 serum samples (460 cattle, 460 sheep). Samples were analyzed by indirect enzyme-linked immunosorbent assays using commercial kits (ID N. caninum Indirect Screening Kit; ID Screen Besnoitia Indirect 2.0). Associations between seroprevalence and risk factors were evaluated by Chi-square tests at α < 0.05 using Statistical Package for the Social Sciences v23. Results: The overall seroprevalence of N. caninum was 23.91% in cattle and 5.43% in sheep, while B. besnoiti antibodies were detected in 5.43% and 3.26%, respectively. Higher seroprevalence was observed in the Asir region, among female animals, and in those aged >1-5 years. The Baladi (cattle) and Daen (sheep) breeds were the most affected. Infections were more frequent during summer and under small-scale or open grazing management. Significant correlations were found between N. caninum seroprevalence and both species and sex (p < 0.05), and between B. besnoiti seroprevalence and sheep sex (p < 0.05). Conclusion: This study provides the first comprehensive evidence of N. caninum and B. besnoiti infections in cattle and sheep in KSA, underscoring their potential economic and reproductive implications. These findings highlight the need for improved biosecurity, control of vector exposure, and regulation of animal movement to mitigate transmission. Future studies should include molecular confirmation and broader geographical coverage to clarify transmission dynamics and genetic diversity of these parasites.