Disease dynamics and severity control of an established environmentally transmitted parasite

Abstract

For many wildlife impacted by invasive pathogens, demand for management that curbs impacts can exist long after emergence, yet there are few examples where management is demonstrated as both efficacious and sustainable. We investigated disease dynamics in a bare-nosed wombat (Vombatus ursinus) population where there is demand for disease management and undertook an intervention to test the capacity to curb the severity of sarcoptic mange (caused by Sarcoptes scabiei) using relatively simple therapeutic delivery methods. Using transect surveys, we observed large numbers of bare-nosed wombats (average 50 per survey) in our survey area (ca 20 hectares), finding wombats were healthy (median body condition 4/5) and had a low and stable apparent prevalence of mange (average 3.3%) over 20 months. We undertook a monthly disease management programme for six months, focused on targeted therapeutic (fluralaner) interventions delivered to free-ranging individuals with signs of sarcoptic mange. Our programme, applicable to other wildlife and wombat-mange situations, successfully reduced disease severity among all wombats surveyed, as well as for individuals who could be followed repeatedly. This empirical study establishes an efficacious, feasible and sustainable method of wildlife disease management in an endemic epidemiological setting, something that is rare in the literature on wildlife disease control.