The final frontier: using carcasses for one health surveillance at the ecosystem interface.

Anthropogenic activities such as agricultural intensification, urbanisation, globalisation, and climate change are accelerating disease emergence globally, yet surveillance systems have largely overlooked the critical role of vertebrate carcasses in pathogen transmission. This omission is concerning because animal mass mortality events (MMEs) are increasing in frequency and magnitude, while populations of key vertebrate scavengers, especially obligate scavengers like vultures, are declining, resulting in longer carcass persistence and altered disease risks. Carcasses serve as essential resources in food webs but also act as complex microbe transmission hubs through direct consumption, environmental contamination, vector-mediated dispersal, and increased host aggregation, facilitating cross-species and trophic spillover events. Scavengers can amplify or mitigate microbe transmission: their consumption of carcasses can remove infectious material, but their mobility and sociality may also disperse potential pathogens across large areas. Technological advances, including remote sensing, camera traps, GPS telemetry, and machine learning, now enable detailed tracking of scavenger-carcass interactions and identification of transmission hotspots. Simultaneously, metagenomic sequencing allows untargeted detection of known and novel pathogens in carcass-associated microbial communities ("necrobiome"), with portable platforms supporting field-based surveillance. Integrating carcass-based surveillance into One Health frameworks through interdisciplinary collaboration among ecologists, epidemiologists, and data scientists offers a proactive approach to early outbreak detection, improved pandemic preparedness, and ecosystem health monitoring. Given the projected increase in climate-driven mortality events, incorporating carcass-scavenger networks into disease surveillance strategies is a valuable and under-utilised complement to existing approaches, enhancing our ability to monitor and mitigate emerging infectious diseases.