Characterization of Demodex musculi infestation, associated comorbidities, and topographic distribution in a mouse strain with defective adaptive immunity

Melissa A. Nashat , Kerith R. Luchins , Michelle L. Lepherd , Elyn R. Riedel , Joanna Nina Izdebska , Neil S. Lipman


A colony of B6.Cg-Rag1tm1Mom Tyrp1B-w Tg(Tcra,Tcrb)9Rest (TRP1/TCR) mice presented with ocular lesions and ulcerative dermatitis. Histopathology, skin scrapes, and fur plucks confirmed the presence of Demodex spp. in all clinically affected and subclinical TRP1/TCR mice examined (n = 48). Pasteurella pneumotropica and Corynebacterium bovis, both opportunistic pathogens, were cultured from the ocular lesions and skin, respectively, and bacteria were observed microscopically in abscesses at various anatomic locations (including retroorbital sites, tympanic bullae, lymph nodes, and reproductive organs) as well as the affected epidermis. The mites were identified as Demodex musculi using the skin fragment digestion technique. Topographic analysis of the skin revealed mites in almost all areas of densely haired skin, indicating a generalized demodecosis. The percentage of infested follicles in 8- to 10-wk-old mice ranged from 0% to 21%, and the number of mites per millimeter of skin ranged from 0 to 3.7. The head, interscapular region, and middorsum had the highest proportions of infested follicles, ranging from 2.3% to 21.1% (median, 4.9%), 2.0% to 16.6% (8.1%), and 0% to 17% (7.6%), respectively. The pinnae and tail skin had few or no mites, with the proportion of follicles infested ranging from 0% to 3.3% (0%) and 0% to 1.4% (0%), respectively. The number of mites per millimeter was strongly correlated with the percentage of infested follicles. After administration of amoxicillin-impregnated feed (0.12%), suppurative infections were eliminated, and the incidence of ulcerative dermatitis was dramatically reduced. We hypothesize that the Rag1-null component of the genotype makes TRP1/TCR mice susceptible to various opportunistic infestations and infections, including Demodex mites, P. pneumotropica, and C. bovis. Therefore, Rag1-null mice may serve as a useful model to study human and canine demodecosis. D. musculi should be ruled out as a contributing factor in immunocompromised mouse strains with dermatologic manifestations.
Author Melissa A. Nashat
Melissa A. Nashat,,
, Kerith R. Luchins
Kerith R. Luchins,,
, Michelle L. Lepherd
Michelle L. Lepherd,,
, Elyn R. Riedel
Elyn R. Riedel,,
, Joanna Nina Izdebska (FB / DIZP)
Joanna Nina Izdebska,,
- Department of Invertebrate Zoology and Parasitology
, Neil S. Lipman
Neil S. Lipman,,
Other language title versions
Journal seriesComparative Medicine, ISSN 1532-0820, (A 30 pkt)
Issue year2017
Publication size in sheets0.7
ASJC Classification3400 General Veterinary; 1300 General Biochemistry, Genetics and Molecular Biology
Languageen angielski
Score (nominal)30
Score sourcejournalList
ScoreMinisterial score = 30.0, 28-01-2020, ArticleFromJournal
Publication indicators WoS Citations = 6; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 0.314; WoS Impact Factor: 2017 = 0.585 (2) - 2017=0.884 (5)
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