Risk of exotic disease introduction and propagation in the Austrian swine trade network

The importation of live pigs poses a significant risk for introducing exotic diseases, threatening animal health, welfare, and food security. We used a database of 2021 daily Austrian pig movement records to model the spread of an introduced infectious disease. We simulated within-holding infection dynamic with a stochastic Susceptible-Exposed-Infectious-Removed (SEIR) model using ASF-like parameters, and considered two between-holding transmission pathways: direct, via trade, and indirect within a 5-km radius.Our results revealed that the epidemic affected 0.2% of the initial pig population and 2% of holdings, and reached 10% of the municipalities. Most holding-to-holding transmission occurred over short-distance (54.7% being intra-municipal, while inter-municipal transmission averaged 7.8 km). On average, 5.6 long-distance transmission events (i.e., > 2 SD above the mean trade distance) occurred per simulation, facilitating large-scale outbreaks. Critically, early-stage projections provided significantly more precise estimates of final size and progression patterns than later forecasts, enabling targeted interventions before uncertainty escalates. Static networks overestimated affected municipalities by 8.6 times by disregarding trade timing. We highlighted that the first 40 days are critical for epidemic control when the introduction occurs during a low-trade period (January), but this period is reduced to 20 days during high-trade periods.