Characterising a sarcoptic mange epizootic in quenda (Isoodon fusciventer)

Abstract

Sarcoptic mange, a parasitic skin disease caused by Sarcoptes scabiei, is an emerging conservation threat to some Australian wildlife species. As a zoonotic and multi-host disease, it has the capacity to exploit different hosts, creating management challenges for susceptible wildlife populations that may suffer high rates of morbidity and mortality. Sarcoptic mange was identified in quenda (Isoodon fusciventer) in a peri-urban region of Perth, Western Australia in 2019. By mid-2021, reported cases were distributed across 107ha. This retrospective study reviews the spatiotemporal distribution, clinical signs and risk factors for sarcoptic mange in quenda from a metropolitan region. Preliminary epidemiological parameters for the outbreak are described, including period prevalence of infested individuals, spatiotemporal analyses, clinical signs of mange, and preliminary risk factor analyses. The period prevalence of sarcoptic mange between July 1, 2019 and June 30, 2021 was 26.9% (CI 95%; 21.2, 33.5) with a mortality rate of 39.6%, owing to severity of disease or secondary complications. Sarcoptic mange was detected more frequently in adult quenda than juveniles (OR: 176.8, CI 95%: 10.7, 2930.1), with adult males more affected than adult females (OR: 3.5, CI 95%: 1.5, 8.4). Clinical signs of disease presented on the rump and tail (100%), followed by the limbs and digits (61.5%). The most common clinical signs recorded were alopecia (92.3%), erythema (46.2%) and open wounds (42.3%). This is the first documented example of a geographically expanding and propagating epizootic of sarcoptic mange in quenda, with implicit welfare and conservation concerns for the species, alongside potential for cases in humans and domestic species that cohabit with or handle quenda in the urban environment. Further, the detection of cases through wildlife rehabilitation centres highlights the critical role such organisations play in conservation and passive surveillance for wildlife diseases of conservation or public and domestic animal health importance.

Keywords: Epidemiology; Isoodon fusciventer; Quenda; Sarcoptes scabiei; Sarcoptic mange; Zoonotic disease.

Graphical abstract

Fig. 1

Prevalence of sarcoptic mange in population groups of quenda (Isoodon fusciventer) admitted to care from Roleystone, Western Australia between July 1, 2019 and June 30, 2021.

Fig. 2

Frequency of infestation by location on the body recorded from 26 quenda (Isoodon fusciventer) with sarcoptic mange admitted to care at Darling Range Wildlife Shelter from Roleystone, Perth, Western Australia from July 1, 2019 to June 30, 2021. (Image: Katerina Ryabtseva).

Fig. 3

Common clinical signs of sarcoptic mange in quenda (Isoodon fusciventer) from Roleystone, Perth, Western Australia in animals admitted to Darling Range Wildlife Shelter between July 1, 2019 and June 30, 2021. A: The early consolidation phase of the disease, with visible erythema and alopecia on rump, flanks and paws and lesions developing on the face; B: Alopecia and emaciation in a quenda undergoing treatment; C: Severe chronic disease evident by extensive deep fissures throughout the epidermis, emaciation, hyperkeratosis, alopecia and lethargy; D: Papillomatous lesions on the posterior dorsal region of a quenda undergoing treatment for sarcoptic mange. (Images: Darling Range Wildlife Shelter).

Fig. 4

Density of sarcoptic mange cases in quenda (Isoodon fusciventer) and potential outbreak extent in Roleystone, Perth, Western Australia from July 2019 to June 2021.

Supplementary Fig. 1

Phylogenetic relationships of Sarcoptes scabiei isolate obtained from a Quenda in WA with S. scabiei isolates obtained from other Australian hosts as estimated using cytochrome oxidase subunit 1 (cox1) gene sequences (382bp). Evolutionary history was inferred using the neighbour-joining method supported with bootstrap test of 1000 replicates (values > 50% shown). Otodectes cynotis is used as the out-group.

Supplementary Fig. 2

Confidence of freedom of disease for sarcoptic mange in quenda (Isoodon fusciventer) in the Perth region, Western Australia, from admission data provided by Darling Range Wildlife Shelter and Kanyana Wildlife Rehabilitation Centre from July 1, 2019–June 30, 2021.

Supplementary Fig. 3

Distribution of male and female quenda (Isoodon fusciventer) diagnosed with sarcoptic mange from Roleystone, Perth, Western Australia and admitted to Darling Range Wildlife Shelter between July 1, 2019 and June 30, 2021 and potential geographical extent of the disease outbreak.