Paradoxes and synergies: optimizing management of a deadly virus in an endangered carnivore

Abstract

Management of pathogen transmission is often hindered by uncertainties in the efficacy of and interactions between intervention strategies, sometimes resulting in unintended negative consequences. Yet outbreaks of infectious disease can have serious consequences for wildlife population health, especially species of conservation concern. The endangered Florida panther, for example, experienced an outbreak of feline leukemia virus (FeLV) in 2002-2004, and continues to be affected by this deadly virus. Ongoing management efforts aim to mitigate the effects of FeLV on panthers with limited empirical information about which strategies are most effective and efficient. We used a simulation-based approach to determine optimal FeLV management strategies. We simulated use of proactive management interventions (i.e., proactive vaccination) as well as three reactive strategies, including vaccination in the face of an outbreak, test and removal protocols, and temporary spatial segregation of the panther population. Vaccination strategies included partial vaccine immunity, an understudied type of vaccine imperfection. We compared the effectiveness of different strategies in mitigating FeLV mortalities and duration of outbreaks. Results showed that inadequate proactive vaccination can paradoxically increase the number of disease-induced mortalities in FeLV outbreaks, at least in part due to partial vaccine immunity. Combinations of proactive vaccination with reactive test- and-removal or vaccination had a synergistic effect in reducing impacts of FeLV outbreaks. Temporary spatial restrictions were unlikely to be effective under realistic conditions. Our results highlight the importance of integrating management and modeling approaches to identify unexpected consequences and synergies in pathogen management interventions and aid in conservation of at-risk species.Significance StatementManaging outbreaks of infectious disease is fraught with uncertainties such that seemingly helpful interventions can have unintended negative consequences. We used a simulation approach to determine optimal pathogen management strategies in an endangered carnivore, the Florida panther (Puma concolor coryi), which continues to be affected by outbreaks of feline leukemia virus. We tested interventions including proactive vaccination, reactive vaccination, test-and-removal, and temporary spatial restrictions. We found that inadequate proactive vaccination can counterintuitively increase disease-related mortalities. In contrast, we identified synergies between proactive and reactive strategies that will be key for ongoing conservation of the iconic Florida panther. The results of this study demonstrate the importance of linking modeling and management to optimize pathogen control and avoid unexpected negative consequences.