Mitochondrial genome sequencing reveals potential origins of the scabies mite Sarcoptes scabiei infesting two iconic Australian marsupials

Tamieka A Fraser,Adam Polkinghorne,Michael Charleston,Roz Holme,Renfu Shao,Alynn Martin,Nicholas M Fountain-Jones,Scott Carver,Pam Whiteley

doi:10.1186/s12862-017-1086-9

Abstract

BackgroundDebilitating skin infestations caused by the mite, Sarcoptes scabiei, have a profound impact on human and animal health globally. In Australia, this impact is evident across different segments of Australian society, with a growing recognition that it can contribute to rapid declines of native Australian marsupials. Cross-host transmission has been suggested to play a significant role in the epidemiology and origin of mite infestations in different species but a chronic lack of genetic resources has made further inferences difficult. To investigate the origins and molecular epidemiology of S. scabiei in Australian wildlife, we sequenced the mitochondrial genomes of S. scabiei from diseased wombats (Vombatus ursinus) and koalas (Phascolarctos cinereus) spanning New South Wales, Victoria and Tasmania, and compared them with the recently sequenced mitochondrial genome sequences of S. scabiei from humans.ResultsWe found unique S. scabiei haplotypes among individual wombat and koala hosts with high sequence similarity (99.1% - 100%). Phylogenetic analysis of near full-length mitochondrial genomes revealed three clades of S. scabiei (one human and two marsupial), with no apparent geographic or host species pattern, suggestive of multiple introductions. The availability of additional mitochondrial gene sequences also enabled a re-evaluation of a range of putative molecular markers of S. scabiei, revealing that cox1 is the most informative gene for molecular epidemiological investigations. Utilising this gene target, we provide additional evidence to support cross-host transmission between different animal hosts.ConclusionsOur results suggest a history of parasite invasion through colonisation of Australia from hosts across the globe and the potential for cross-host transmission being a common feature of the epidemiology of this neglected pathogen. If this is the case, comparable patterns may exist elsewhere in the ‘New World’. This work provides a basis for expanded molecular studies into mange epidemiology in humans and animals in Australia and other geographic regions.

Highlights

Debilitating skin infestations caused by the mite, Sarcoptes scabiei, have a profound impact on human and animal health globally
Because the choice of genetic loci for molecular epidemiology studies has influenced previous studies of S. scabiei origins and host specificity, we examined individual mitochondrial genes to aid in the selection of gene targets for downstream investigations into the phylogenetic relationships of mites from a range of hosts and geographic locations, for Australian studies but for global comparisons
S. scabiei mitochondrial genome assembly and annotation identify new haplotypes in Australian marsupials Successful full-length mitochondrial genome assembly was confirmed for all samples

Summary

Introduction

Debilitating skin infestations caused by the mite, Sarcoptes scabiei, have a profound impact on human and animal health globally. In remote Aboriginal communities, up to 50% of children suffer from S. scabiei infestations, resulting in endemic transmission and severe cases of scabies induced pyoderma [9]. These communities share communal space with mange infested dogs, a risk for continuous zoonotic transmission [10]. S. scabiei has been documented to infest iconic Australian native species, including wombats (Vombatus ursinus, Lasiorhinus latifrons) [11], wallabies (Wallabie bicolor, Macropus agilis) [12, 13], koala (Phascolarctos cinereus) [14], southern brown bandicoot (Isoodon obesulus) [15], and dingo (Canis lupus dingo) [6]. Recent studies suggests a rise in mange cases in koalas in populations from southern Australia [18]

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