I>Demodex injai : A New Species of Hair Follicle Mite (Acari: Demodecidae) from the Domestic Dog (Canidae)

Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, United States
Journal of Medical Entomology (Impact Factor: 1.95). 04/2003; 40(2):146-9. DOI: 10.1603/0022-2585-40.2.146
Source: PubMed


Demondex injai sp. nov. is described from the hair follicles of a domestic dog in Columbus, OH in October 1996. The mites occupy follicles from the orifice down to and into the sebaceous glands. The individual host may harbor both this new species and D. canis. A comparison of these two species is provided for identification purposes.

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    • "In none of the samples both mite species (D. canis and D. injai) were simultaneously detected. Both D. canis and D. injai mites were identified microscopically, after measuring the gnathosoma, podosoma, and opisthosoma, according to the original descriptions (Nutting and Desch 1978; Desch and Hillier 2003). Hair samples and skin scrapings were conserved in physiological saline solution and stored at −20 °C until DNA extraction. "
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    ABSTRACT: The identification of Demodex injai as a second Demodex species of dog opened new questions and challenges in the understanding on the Demodex-host relationships. In this paper, we describe the development of a conventional PCR technique based on published genome sequences of D. injai from GenBank that specifically detects DNA from D. injai. This technique amplifies a 238-bp fragment corresponding to a region of the mitochondrial 16S rDNA of D. injai. The PCR was positive in DNA samples obtained from mites identified morphologically as D. injai, which served as positive controls, as well as in samples from three cases of demodicosis associated with proliferation of mites identified as D. injai. Furthermore, the PCR was positive in 2 out of 19 healthy dogs. Samples of Demodex canis and Demodex folliculorum were consistently negative. Skin samples from seven dogs with generalized demodicosis caused by D. canis were all negative in the D. injai-specific PCR, demonstrating that in generalized canine demodicosis, mite proliferation is species-specific. This technique can be a useful tool in the diagnosis and in epidemiologic and pathogenic studies.
    Full-text · Article · Jul 2013 · Parasitology Research
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    • "Mites of the genus Demodex are commonly found in the hair follicles and sebaceous glands of most mammals. In general, Demodex are considered to be host-species speci�c and some hosts can be infested with two or more distinct species (e.g., D. canis, D. injai, an undescribed short form Demodex sp. in dogs, D. brevis and D. folliculorum in humans, D. odocoilei in white-tailed deer (Odocoileus virginianus), and D. bovis in cattle) [1] [2] [3] [4] [5]. In general, Demodex infestations can vary widely in clinical presentation (from asymptomatic animals to cases with variable extends of alopecia, varying degrees of thickening of the skin, to cutaneous nodular lesions and severe dermatitis/furunculosis). "
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    ABSTRACT: Demodex mites, although usually nonpathogenic, can cause a wide range of dermatological lesions ranging from mild skin irritation and alopecia to severe furunculosis. Recently, a case of demodicosis from a white-tailed deer (Odocoileus virginianus) revealed a Demodex species morphologically distinct from Demodex odocoilei. All life cycle stages were considerably larger than D. odocoilei and although similar in size to D. kutzeri and D. acutipes from European cervids, numerous morphometrics distinguished the four species. Adult males and females were and μm in length, respectively. Ova, larva, and nymphs measured , , and μm in length, respectively. For phylogenetic analyses, a portion of the 18S rRNA gene was amplified and sequenced from samples of the WTD Demodex sp., two Demodex samples from domestic dogs, and Demodex ursi from a black bear. Phylogenetic analyses indicated that the WTD Demodex was most similar to D. musculi from laboratory mice. A partial sequence from D. ursi was identical to the WTD Demodex sequence; however, these two species can be differentiated morphologically. This paper describes a second Demodex species from white-tailed deer and indicates that 18S rRNA is useful for phylogenetic analysis of most Demodex species, but two morphologically distinct species had identical partial sequences. Additional gene targets should be investigated for phylogenetic and parasite-host association studies.
    Full-text · Article · Jan 2013
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    • "Clinically, the most common is Demodex canis which are located in the hair follicle, sebaceous duct, and sebaceous gland (Scott et al. 2001). Demodex injai which lives in the hair follicle and inside the sebaceous gland (Desch and Hillier 2003) are associated with truncal seborrhea oleosa and alopecia (Mueller and Bettney 1999; Hillier and Desch 2002). Finally, a short form of Demodex mite that has tentatively been named Demodex cornei (Shipstone 2000), and which we call Demodex sp. "
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    ABSTRACT: Canine demodicosis is a severe and highly prevalent dermatologic disease in dogs. Pet dogs can be affected by three recognized Demodex species that can produce clinical effects. In this paper, three morphological types of Demodex mites have been isolated from Spanish dogs. A complete morphobiometrical study of each one has been carried out. Morphological and biometrical studies revealed three closely related populations with some distinctive characteristics and could be identified as Demodex canis, Demodex injai, and Demodex sp. "cornei." Furthermore, one population of D. canis from China, different populations of Demodex folliculorum from human skin (Spain and China), D. folliculorum from human eyelashes (Spain), and Demodex brevis from human skin (China) were considered to find out the level of variation between different species and geographical origin. The aim of the present study is to assess the usefulness of mitochondrial DNA molecular markers in establishing phylogenetic relationships and resolve taxonomic questions in Demodex mites. Molecular studies based on the amplification and sequencing of the 16S rDNA and cytochrome oxidase I mitochondrial genes did not show clear differences between the three morphotypes considered. Furthermore, phylogenetic relationships in Demodex mites were analyzed. The resulting phylogenetic trees show that Demodex species from dogs were gathered together, and populations of D. folliculorum from humans appear together in a different branch; however, D. brevis from humans seemed to be more distant. Our results show that cytochrome oxidase I region is a useful tool to solve different taxonomic questions at the species and population level and to infer phylogenetic relationships in Demodex species. However, 16S mitochondrial rDNA seems a good marker for comparisons at an interspecies level, but not at a population level in this group of mites. Furthermore, from genetic distance and divergence data, we would suggest that D. canis, D. injai, and Demodex sp. cornei are polymorphisms of the same species.
    Full-text · Article · Aug 2012 · Parasitology Research
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