Surveillance of Schmallenberg virus in cattle populations in Northeastern Brazil.

The objective of this study was to conduct a serological investigation of Schmallenberg virus (SBV) infection in cattle raised in the State of Alagoas. A total of 460 serum samples from the Agricultural Defense Agency of Alagoas (ADEAL) serum bank were analyzed. These samples were collected from unvaccinated cattle on 100 properties across 99 municipalities in Alagoas, representing the three mesoregions: Agreste, Leste, and Sertão. Serological diagnosis was performed using commercial indirect Enzyme-Linked Immunosorbent Assay (ELISA) kit. The results showed that 0.87% (4 out of 460) of the samples yielded questionable results in the indirect ELISA (with calculated percentages > 50.00% and ≤ 60.00%). Upon further testing with competitive ELISA, only one sample tested positive. These findings underscore the need to strengthen regional surveillance and control strategies for emerging pathogens. Additionally, further studies, including viral isolation from both ruminants and vectors, are crucial to confirm the circulation of this pathogen. Such comprehensive investigations are essential for improving our understanding of SBV dynamics and for developing effective control measures.