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

TL;DR

This study models how swine trade in Austria could spread exotic diseases, showing that early action is key to preventing large outbreaks.

Contribution

The study introduces a dynamic network model for swine trade that accounts for timing and long-distance transmission risks.

Findings

The highest-import municipality (M1514) is a likely entry point for exotic diseases.

Long-distance transmission events drive about 20% of outbreak spread.

Static network models overestimate affected municipalities by 8.9-fold.

Abstract

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).

•Highest-import municipality (M1514) is a likely entry point, import ∼30% more•Long-distance transmission seed distant cluster, driving ∼20% of outbreak spread•Static networks ignoring timing overestimate affected municipalities by 8.9-fold•Control windows: 20/40 days; long-distance transmission probability rises after 100 days

Highest-import municipality (M1514) is a likely entry point, import ∼30% more

Long-distance transmission seed distant cluster, driving ∼20% of outbreak spread

Static networks ignoring timing overestimate affected municipalities by 8.9-fold

Control windows: 20/40 days; long-distance transmission probability rises after 100 days

Animal health management; animal science; food animal veterinary medicine; porcine epidemiology

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