Equine viral arteritis in horses undergoing pre‐export testing in Spain (2016–2023): Seroprevalence estimates and diagnostic performance of a commercial indirect ELISA

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Background Equine viral arteritis (EVA) is a contagious disease that affects equine reproduction and international trade. Despite its importance, epidemiological data from Spain are limited. This study aimed to assess EVA seroprevalence and evaluate the diagnostic performance of a commercial ELISA in horses before export. Methods From 2016 to 2023, 5000 serum samples from horses across 16 Spanish autonomous communities were tested using a commercial indirect ELISA. Samples with inconclusive results, or those submitted with specific requests, underwent virus neutralisation testing (VNT). Diagnostic performance was assessed using receiver operating characteristic curve analysis and the kappa coefficient. Results The apparent seroprevalence was 13.3% (664/5000), and the Rogan–Gladen‐adjusted seroprevalence was 2.3%. Apparent seroprevalence decreased over time, and adjusted estimates reached 0.0% from 2020 onwards. ELISA showed 98.9% sensitivity and 88.7% specificity, with substantial agreement with the VNT ( κ = 0.68). Seroprevalence increased with age and was highest in Andalusia and Castile and Leon. Limitations The study included only horses undergoing pre‐export testing and was dominated by Spanish purebred horses; therefore, findings may not represent the wider Spanish equine population. Conclusion The declining EVA seroprevalence among horses undergoing pre‐export testing may reflect improved control measures. ELISA may be suitable for pre‐export screening, with VNT confirmation recommended for values above 37.14%.