Sarcoptes scabiei (Linnaeus, 1758)

Niedringhaus, Kevin D., Brown, Justin D., Sweeley, Kellyn M. & Yabsley, Michael J., 2019, A review of sarcoptic mange in North American wildlife, International Journal for Parasitology: Parasites and Wildlife 9, pp. 285-297 : 286

2. Sarcoptes scabiei

2.1. Phylogeny and classification

Sarcoptes scabiei (Linnaeus, 1758) is in the superorder Acariformes and order Sarcoptiformes . It is within the superfamily Sarcoptoidea , and family Sarcoptidae . Sarcoptidae contains three subfamilies including Sarcoptinae which consists of four genera, including Sarcoptes ( Desch, 2001; Zhang, 2013). It has been suggested that S. scabiei is a single heterogenous species that exhibits a high degree of host specificity but has some level of cross-infectivity ( Stone et al., 1972; Pence et al., 1975; Fain, 1978; Arlian et al., 1984b; Zahler et al., 1999). Traditionally, variant forms of S. scabiei have been identified based on the host species from which they were detected (e.g. Sarcoptes scabiei var. canis , Sarcoptes scabiei var. suis , etc.) and inability to cause pronounced clinical disease in taxonomically distinct hosts ( Fain, 1968; Ruiz et al., 1977; Fain, 1978; Arlian et al., 1984b; Arlian et al. 1988b; Arlian et al. 1989). However, few morphological differences are seen among mites found on different host species ( Fain, 1968; Fain, 1978). Rather, it is believed that the differences between these variants, which define their host preference, are physiologic and/or genetic ( Pence et al., 1975). Other than human variants being distinct from the ‘animal’ clade, genetic studies conducted to date have not been able to consistently distinguish between different host variants using common gene targets for mites including internal transcribed spacer region-2 (ITS-2) and cytochrome oxidase 1 (COI) ( Zahler et al., 1999; Berrilli et al., 2002; Skerratt et al., 2002; Gu and Yang, 2008; Gu and Yang, 2009; Peltier et al., 2017).

In contrast, consistent clustering in geographic or host specificity can still be obtained using microsatellites and mitochondrial DNA as markers, which shows uncertainty for the usefulness of ITS-2 as a gene for S. scabiei phylogenetic analyses ( Zahler et al., 1999; Walton et al., 2004; Soglia et al., 2007; Alasaad et al., 2009; Rasero et al., 2010; Gakuya et al., 2011). There is potential for microsatellites and mitochondrial DNA to have value, but there is little consistency in which microsatellites or targets are chosen inhibiting the ability to compare large datasets. The Sarcoptes -World Molecular Network was created to improve methods of Sarcoptes detection as well as provide a central location for comparing phylogenetic data ( Alasaad et al., 2011). A formal consensus on the taxonomy based on morphological and genetic features has not been made other than to suggest that all Sarcoptes scabiei variants are the same genetically diverse species ( Fraser et al., 2016).