The tripartite framework of parasite virulence: drivers, consequences, and implications for wildlife and public health.
Parasite virulence, a key regulator in ecosystems, critically influences wildlife population dynamics and food web stability. Although classical co-evolutionary theory posits a trend toward benign symbiosis, empirical evidence demonstrates that virulence is shaped by complex trade-offs among host, parasite, and environmental factors. This study provides a comprehensive analysis of the drivers of virulence, including host strategies (immune competence, density-dependent transmission, spatial behavior), parasite strategies (transmission mode,within-host competition, genetic diversity), and environmental dimensions (climate change, habitat fragmentation, species invasions). We further examine how disruptions to this tripartite equilibrium can precipitate population declines, biodiversity loss, and increased zoonotic spillover risk. Within the "One Health" framework, we highlight the necessity of maintaining dynamic balance among virulence, hosts, and the environment to safeguard ecological integrity and public health. Accordingly, we propose integrated management strategies to sustain these interactions. This work underscores the interdependence of virulence evolution and ecosystem processes, offering insights for proactive conservation and disease mitigation.