Invasive and emerging pathogens can have dramatic impacts on wildlife health, at individual and population scales. Their impacts at individual levels can be diverse and can cause transmission level consequences, such as through behavioral modification. Yet pathology caused by such pathogens can be remarkably conserved across species, meaning an appreciation of ‘disease phenotypes’ from a single species can be broadly applicable. Sarcoptic mange (etiologic agent Sarcoptes scabiei) is among the most widespread of emerging and invasive pathogens of wildlife, affecting more than 100 mammalian species globally. This pathogen exhibits continued expansion into new host species, and conserved pathology among host species. In Australia, mange has been shown to affect some of the continent’s most iconic mammals (koala, wallabies, and wombats). The bare-nosed wombat (Vombatus ursinus) is the most severely affected, with localized outbreaks capable of causing population extirpation events. Research has shown physiological and behavioral impacts of mange disease on wombats (consistent with other host species), and in this study we extend this phenotype to previously untested pathological consequences; circadian rhythms and metabolic impacts.
Results/Conclusions
Wombats infected with mange experienced increased energetic pressures and dramatic shifts in circadian activity patterns, relative to healthy counterparts. As disease severity increased, field metabolic rates (ml CO2 / g h) increased (R2 =0.9013) concomitantly. Increasing disease severity also resulted in progressive breakdown in the consistency of circadian activity cycles, including diminished force of activity and increased shivering during cooler ambient temperatures. The combination of these progressive physiological and behavioral changes, and those already known for this host species, likely contributes to mortality associated with infection. This research adds to the body of knowledge on the phenotype of sarcoptic mange disease in wildlife hosts. Results are applicable to the development of therapeutic agents and approaches to rehabilitation. Importantly, it contributes to understanding disease impacts that can modify transmission dynamics. Treatment of individuals and populations can ameliorate pathogenic impacts, and this is a target for conservation strategies.