The Cattle Trading Network and Its Effect on the Spread of Brucellosis in Paraná, Brazil

This study analyzed the cattle trade network in Paraná, Brazil, for the years 2018 and 2019 to identify potential movement patterns that could contribute to the spread of brucellosis among farms. The brucellosis statuses of 1757 farms were incorporated into the analysis. Network parameters of farms with a known brucellosis infection status were statistically compared between infected and non-infected farms using traditional techniques and the quadratic assignment procedure. A multilinear regression model (MLR) was used to consider known risk factors for brucellosis infection in conjunction with the network parameters. The cattle trade network in Paraná during the study period comprised 115,296 farms linked by 608,807 cattle shipments. The movement pattern was marked by a high concentration of movements to and from a small percentage of farms. The existence of such highly connected farms could facilitate the transmission of communicable diseases via the cattle trade in Paraná. The trading communities in Paraná exhibited a spatial pattern, with proximate farms more likely to engage in trade. Brucellosis-infected farms traded more frequently than non-infected farms (odds ratio [OR] 3.61), supplied cattle to other farms more often than the regional average (OR 2.12), and received more cattle (OR 2.78). The in-degree and out-degree were associated with brucellosis infection on the farm. The mean shortest path between infected farms was significantly shorter than that between non-infected farms (4.14 versus 4.49, p = 0.004, OR 1.39). In the MLR, a higher out-degree was positively associated with infected farms after accounting for previously identified risk factors. This novel information offers insights into the factors driving the current endemic situation in the study area and can inform the development of targeted animal health policies.