Zoonotic and transboundary infectious threats increasingly emerge through dynamic wildlife–livestock–human interfaces in which reservoir circulation, livestock amplification, exposure networks, and surveillance intensity can change faster than conventional periodic reviews. This living systematic review examines how heterogeneous signals should be interpreted without conflating pathogen detection with validated transmission, reservoir attribution, outbreak magnitude, or intervention effectiveness. Peer-reviewed evidence published from 2017–2026 was organized using a prespecified living-review framework covering surveillance signals, reservoir dynamics, transmission pathways, exposure networks, intervention evidence, preparedness, and methodological uncertainty. Search, selection, extraction, appraisal, and synthesis procedures were designed for reproducibility and version control. Heterogeneous evidence was synthesized without forced quantitative pooling. No search-derived count is reported where a reconciled value was unavailable in the review-selection record. The evidence indicates that actionable warning can arise from genomic surveillance, serology, aggregated livestock sampling, slaughterhouse sentinels, wildlife sampling, and integrated human–animal–vector systems, but these signals differ fundamentally in what they establish. Reservoir inference is sensitive to species, specimen, timing, and assay choice; transmission evidence ranges from field association to controlled experimentation and model-based inference; and much preparedness evidence remains observational or operational rather than causal. A proposed evidence-state architecture therefore separates detection, interpretation, cross-interface attribution, and response consequence. One Health preparedness benefits from linking heterogeneous surveillance streams while retaining explicit boundaries between signal and event, association and pathway, reservoir evidence and reservoir proof, and implementation activity and demonstrated effectiveness. Living updating is most defensible when changes are versioned, uncertainty is retained, and new evidence can revise rather than merely accumulate prior interpretations.
