Integrating Citizen Science and Remote Sensing Data to Identify Key Environmental Factors Influencing H5N1 Avian Influenza Virus Potential Spillover Risk in the Philippines

Highly pathogenic avian influenza (HPAI) virus presents a serious threat to poultry and public health worldwide, with transmission dynamics shaped by avian migration patterns and environmental conditions. Recent outbreaks in the Philippines highlight the urgent need for effective control measures. While previous studies have shown the importance of waterfowl-to-poultry transmission and farm-to-farm spread, the spillover risk to local avian species remains underexplored. This study aimed to examine H5N1-HPAI outbreaks in poultry in relation to environmental factors and local avian species in the Philippines. We applied a two-step ecological niche modelling approach using maximum entropy algorithms. First, environmental variables from remote sensing images were used to predict the distribution of 10 common avian species based on citizen science data from the eBird platform. Next, these avian distribution data were combined with environmental variables to create a risk map for H5N1-HPAI outbreaks in the Philippines. The H5N1-HPAI risk model demonstrated strong predictive performance, with an AUCROC value of 0.936 ± 0.026. Key factors contributing to predicted H5N1-HPAI risk included precipitation levels, population density, and avian species such as the Eurasian Tree Sparrow and Zebra Dove. The higher risk of spillover for the two local avian species may be due to their shared similar environmental signatures with outbreak poultries. The risk map highlighted Metro Manila and Central Luzon as high-risk regions of H5N1-HPAI. This study identified the main clusters and environmental factors associated with avian influenza outbreaks in poultry in the Philippines. Additionally, the transmission risk may threaten the local avian population.