A One Health model evaluating the role of a wild carnivore in mitigating multi-host anthrax outbreaks

Anthrax, caused by Bacillus anthracis , is a globally distributed zoonosis with major ecological, economic, and health consequences, particularly in agropastoral systems. For environmentally persistent pathogens, transmission is shaped by carcass persistence, environmental amplification, and host exposure. Carnivore scavenging and predation may influence these pathways, but are often omitted from multi-host disease models. We developed a deterministic One Health model framework linking humans, livestock, wild herbivores, environmental spores, and hyena scavenging and predation. We simulated nine 180-day scenarios varying hyena population size (N = 0, 20, or 150) and prey preference, parameterized for East African savannas and calibrated to attack rates from Ugandan outbreaks. Monte Carlo sensitivity analyses evaluated uncertainty in transmission, dose–response, scavenging, and environmental parameters. Cumulative human infections were strongly correlated with livestock infections (Pearson’s r = 1.00) and final environmental spore load (Pearson’s r = 0.96). Small and large hyena population sizes reduced mean cumulative human infections by 69% and 71%, compared to the no-hyena baseline. The largest reductions occurred when infected livestock were removed before carcass-mediated sporulation, lowering mean cumulative human infections by 85–86%. These results suggest that scavenging and predation may reduce outbreak severity in environmentally maintained anthrax systems.