Some of the most prominent disease threats to wildlife involve environmental transmission (e.g., chytridiomycosis, bat white nose syndrome, sarcoptic mange). Environmentally transmitted pathogens present major conservation challenges because mitigation efforts must consider control of the pathogen on both the host and in the environment. We designed and implemented an experiment aimed at local eradication of sarcoptic mange (etiologic agent Sarcoptes scabiei mite) from a bare-nosed wombat (Vombatus ursinus) population and the environment (wombat burrows) during a mange epizootic in northern Tasmania, Australia. Our experiment attempted high treatment coverage of wombats exiting/entering burrows to induce population level resistance and over a duration long enough to allow for the environmental reservoir to die.
Results/Conclusions
We show that our experiment changed the declining trajectory of the wombat population and induced a level of population recovery, but was ultimately unsuccessful at pathogen eradication, resulting in the epizootic continuing following completion of the treatment period. Using state-based simulation models of our study system we show how wombat movement between burrows, the length of treatment efficacy, and unexpectedly low delivery success of the treatment were major contributors to disease control failure. We find that overcoming the latter two of these limiting factors has significant potential to transform capacity for successful disease control and localised eradication. Findings here have broad relevance for mitigation of sarcoptic mange in other populations and host species globally, and contribute to other treatable pathogens with environmental transmission.