Application and evaluation of a migratory exposure risk for avian influenza in Ireland (2013~2025)

Avian Influenza (AI) is a zoonotic virus infecting wild birds and poultry. AI can be spread via wild bird migration, especially by waterfowl. On the island of Ireland, most outbreaks in poultry are linked to wild bird contact. Therefore, predicting the exposure to AI through wild birds could help with directing measures and disease preparedness. We retrospectively applied a stochastic simulation model to estimate the migration-mediated exposure risk of AI in Ireland from 2013 to 2025, based on wild bird short distance movements and seasonal migration. Migration routes include the continent of Europe and Iceland as possible source populations and entry routes of AI, given known bird migration pathways. The model estimated the yearly migration-mediated exposure risk and identified peaks in 2020, 2021, and a particular high emerging peak in autumn of 2025. There was a temporal correlation between migration-mediated exposure risk per month with observed outbreaks. However, the predicted migration-mediated exposure risk for the model resulted in consistently higher number of modelled “incursions” relative to the number of outbreaks observed - indicating a need for migration-mediated exposure risk models to be linked to a within-island epidemic model. Preferably one that includes the probability of subsequent infections and detection. This study highlights a benefit for the application of locally tailored risk models, but also the need for future work to collate and analyse data in “real-time” to improve such tools.