The spread of infectious diseases between animals and humans – and even among different animal species – is a complex challenge for public health officials. New research published in suggests that analyzing the social networks of wild bird populations can help predict how highly pathogenic avian influenza (HPAI) viruses spread, potentially improving surveillance efforts and mitigating future outbreaks.
HPAI, commonly known as bird flu, is a concern not only for poultry farmers but also for global health security. As the U.S. Government Accountability Office notes, over 200 zoonotic diseases – those transmissible from animals to humans – exist, and both domestic animals and wildlife contribute to the risk. The recent emergence of new HPAI strains and their ability to infect a growing number of host species underscores the need for more effective monitoring strategies.
Researchers at the University of Leeds and the University of Oxford combined genomic data from 356 HPAI viruses across 33 host species with a large database of wild bird co-occurrence information. This approach, leveraging the principles of social network analysis, allowed them to investigate how the frequency of interaction between different bird species correlated with the genetic similarity of the viruses found in those species. The study, published in PLoS Pathogens, found a significant relationship: species that frequently co-occurred tended to have viruses with smaller genetic differences.
“We calculated 1,687 pairwise genetic distances from the viral genomes,” explained the study authors, “and related these to network metrics. Species pairs with greater co-occurrence frequency showed significantly lower viral genetic distances, even when accounting for other factors.” This suggests that the more often birds interact, the more readily the virus spreads between them, resulting in less genetic divergence over time.
This finding is significant because it moves beyond traditional methods of disease surveillance, which often rely on tracking the virus’s genetic evolution (phylodynamic modeling) without fully considering the role of animal behavior and interactions. By incorporating social network analysis, researchers can gain a more nuanced understanding of transmission pathways.
The implications for disease control are substantial. Currently, the USDA’s Animal and Plant Health Inspection Service (APHIS) tracks HPAI detections in wild birds, recognizing that these animals can carry the virus without showing symptoms and spread it to domestic poultry. However, this research suggests that focusing surveillance efforts on species that frequently interact with each other – identified through social network analysis – could be a more efficient and targeted approach.
The World Health Organization (WHO) continues to monitor influenza viruses, including avian strains, due to their potential to cause pandemics. Understanding how these viruses spread within and between animal populations is crucial for preventing spillover events – the transmission of a virus from an animal to a human.
Researchers also point out that the transmission of HPAI is not solely determined by social network structure. Other factors, such as environmental conditions, migration patterns, and the immune status of different species, also play a role. A related study, published in on bioRxiv, further supports the importance of social networks, demonstrating that the structure of these networks can predict viral genetic distance. However, the interplay between these factors is complex and requires further investigation.
The study authors acknowledge that their analysis is based on co-occurrence data, which provides an indirect measure of interaction. Direct observation of bird behavior would provide more precise information, but is logistically challenging. Despite this limitation, the findings offer a valuable framework for improving HPAI surveillance and preparedness. By integrating social network analysis with genomic data, public health officials can move towards a more proactive and targeted approach to managing this ongoing threat.
The ongoing evolution of HPAI and its ability to jump between species highlights the interconnectedness of animal and human health. Continued research and collaboration are essential to protect both populations from the devastating consequences of zoonotic diseases.
