Clusters of high transmission risk and time series for Equine Infectious Anemia in Brazil.

Abstract

This study identifies high-risk areas for Equine Infectious Anemia (EIA) in Brazil and analyzes the temporal trend of the disease across regions and Federative Units over an 18-year period (2006-2023), using data from the National Animal Health Information System (SIZ). During the analyzed period, 111,826 cases of EIA were reported in Brazil, with a predominance in the Northeast (39.75 %), Central-West (27.56 %), and North (20.95 %) regions. The state of Mato Grosso recorded the highest number of cases (17.02 %), while Sergipe had the lowest (0.36 %). In the incidence risk analysis, the states of Ceará (8287.84/100,000 horses), Roraima (7024.92/100,000 horses), and Maranhão (6761.95/100,000 horses) were particularly notable. High-risk clusters were observed in the states of Amapá, Pará, Maranhão, Roraima, Tocantins, Piauí, Amazonas, Ceará, Mato Grosso, Rondônia, Rio Grande do Norte, and Pernambuco. Although Brazil showed a reduction in the EIA virus infection rate (AAPC: -8.4; CI: -11.2 to -5.4), the South region displayed an increasing trend (AAPC: 6.5; CI: 2.9 to 10.3). The results highlight the importance of spatial, spatiotemporal, and temporal trend analyses in monitoring EIA, enabling the identification of high-risk areas and guiding more effective control policies under the National Equine Health Program.