Geographic risk of classical swine fever in non-free regions in Brazil

Brazil is the fourth largest producer and exporter of pork in the world, standing out for its potential to increase pig production nationwide. Among the diseases that can severely compromise trade relations and cause significant losses in pig production in Brazil, Classical Swine Fever (CSF) is notable for being a highly contagious viral disease with high potential for spreading among domestic and wild pigs, wild boars, and peccaries. The present study aimed to identify high-risk regions for CSF in Brazil through spatial, temporal, and spatiotemporal analyses from 2000 to 2023. During this period, 3189 cases of CSF were detected, all reported exclusively in states within the CSF non-free zone. The Northeast region accounted for 90.31 % (2880/3189) of the total CSF cases, with Ceará reporting the highest number of cases at 1475 (46.25 %), of which 810 were reported in 2018 alone. The North region accounted for 9.69 % (309/3189) of the total cases, with the states of Pará and Amapá being the only ones to report cases of the disease. Temporal trend analysis identified an increase in Piauí (Annual Percentage Change [APC]: 25.58 %), Alagoas (APC: 28.01 %), and Ceará (APC: 17.99 %), a decreasing trend for Pernambuco (APC: 24.49 %), Paraíba (APC: 19.35 %), and Rio Grande do Norte (APC: 11.85 %), and stability in Maranhão (APC: 0.17 %), Pará (APC: 1.61 %), and Amapá (APC: 15.52 %). The spatiotemporal analysis identified the formation of two high-risk clusters: the primary cluster occurred in the Northeast region, specifically in the states of Ceará, Piauí, Rio Grande do Norte, Paraíba, Pernambuco, and Alagoas, between 2018 and 2019, with a total of 1556 CSF cases and Relative Risk (RRs) of 120.02. The secondary cluster was formed by the states of Rondônia, Acre, Amazônia, Roraima, Pará, Amapá, and Mato Grosso, located in the North and part of the Midwest region, for the year 2009, with a total of 309 cases and an RRs of 29.89. In conclusion, the Northeast region is considered high-risk for the emergence of new CSF cases, highlighting the states of Ceará and Piauí, which can be considered important sources of CSF virus spread to other Brazilian states, alerting authorities to the need for disease control actions.