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

Importation of live pigs poses a significant risk for introducing exotic diseases, threatening animal health, welfare, and food security. Using daily Austrian pig movement records from 2021, we modeled the introduction of an infectious disease. Within-holding infection dynamics were simulated with a stochastic Susceptible-Exposed-Infectious-Removed (SEIR) with ASF-like parameters; between-holding transmission occurred via direct trade and indirect local spread within 5-km radius. Across simulations, the epidemic affected 0.2% of pigs and 2% of holdings, reaching 10% of municipalities. Most holding-to-holding transmission was short-distance (54.9% intra-municipal; inter-municipal transmission averaged 7.8 km), but rare long-distance events (mean 5.6 events per simulation > 2 SD above mean trade distance) facilitated large-scale outbreaks. Early-stage projections predicted final size and progression more precisely than later forecasts, supporting timely targeted interventions. Static networks overestimated affected municipalities by 8.9-fold. The first 40 days were critical for epidemic control when introduction occurred in a low-trade period (January), shrinking to 20 days during high-trade periods (April).