How human ecology landscapes shape the circulation of H5N1 avian influenza: A case study in Indonesia.

Background: Highly pathogenic avian influenza H5N1 virus consistently threatens global public health. A better understanding of the virus' circulation mechanism is needed for future epidemic prevention. Previous studies have focused on the correlations between the presence of H5N1 virus and wild bird populations, domestic poultry production, and sociodemographic factors. However, human cultural landscapes and their impact on H5N1 spread have not been adequately explored. Methods: Using 196 HA gene sequences of H5N1 influenza viruses from Indonesia with district-level geographic information, we performed Monmonier barrier and Louvain community detection analyses to explore how human ecological factors impact the circulation of virus and identify barriers to or corridors of dispersal. Results: Spatial discontinuity in the genetic characteristics identified by the Monmonier algorithm were found to mirror the differences in key landscape factors. Our Louvain community detection analysis also found the co-existence of different geographic circulation patterns. The community detection analysis suggests that direct human-related interactions such as poultry transportations between remote areas may result in similar viruses spreading in two distant regions whilst dense localities supported genetically heterogeneous viruses in geographically adjacent areas. Conclusion: Human ecological landscapes shape the circulation mechanism of H5N1 virus in multiple ways contingent upon local context. Physical and cultural barriers may impede its movement between adjacent areas, while natural or human-induced corridors such as wild bird flyways and poultry production networks facilitate its spread between geographically distant areas. Further focus on the importance of cultural landscapes has great potential for increasing our understanding of the circulation of pathogenic H5N1 avian influenza virus in Southeast Asia.