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A previously unidentified Chorioptes species infesting outer ear canals of moose (Alces alces): characterization of the mite and the pathology of infestation

Gete Hestvik1*, Monika Zahler-Rinder23, Dolores Gavier-Widén4, Ronny Lindberg1, Roland Mattsson4, David Morrison5 and Set Bornstein5

Author Affiliations

1 Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, 750 07 Uppsala, Sweden

2 Bavarian Health and Food Safety Authority, Veterinärstrasse 2, D-85764 Oberschleissheim, Germany

3 Institute for Comparative Tropical Medicine and Parasitology, Ludwig Maximilian University, Leopoldstrasse 5, D-80802 Munich, Germany

4 Department of Wildlife, Fish and Environment, National Veterinary Institute (SVA), Box 7073, 750 07 Uppsala, Sweden

5 Department of Parasitology, National Veterinary Institute (SVA), Box 7073, 750 07 Uppsala, Sweden

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Acta Veterinaria Scandinavica 2007, 49:21  doi:10.1186/1751-0147-49-21

Published: 10 September 2007



During the past decade, Chorioptes mites occupying the outer ear canals have been a common finding at routine necropsies of moose (Alces alces) in Sweden, but neither the taxonomy of the mites nor lesions from the infestation have been investigated. In this study, the mites are characterized by morphological and molecular techniques, and the histopathology of the skin of the outer ear canal is described.


External auditory meatuses from 53 necropsied moose were examined for the presence of Chorioptes, and samples from outer ear canals were taken for histopathological and microbiological examination. A proportion of the mites from each moose was identified to species. The DNA was extracted from mites from three moose, and their ITS-2 sequences were determined; these sequences were compared phylogenetically to sequences from other Chorioptes taxa.


Chorioptes mites were found in 43 (81%) of the 53 moose. The mites had morphological and genetic characteristics distinct from those of C. texanus and C. bovis, the two species generally accepted within the genus. Morphology also did not argue for a diagnosis as C. crewei, C. mydaus or C. panda. On histopathology, lesions were characterized by a hyperplastic perivascular to interstitial dermatitis with epidermal hyperkeratosis and crust formation. Dermal inflammatory infiltrates were composed of mixed T- and B-lymphocytes, plasma cells and macrophages, whereas eosinophils were notably uncommon. Staphylococcus aureus was grown from the infested epidermis of five of 14 examined moose.


Chorioptes mite infestation was frequently detected in the outer ear canals of moose in Sweden. The mites were evidently pathogenic, being associated with inflammatory lesions of the external auditory meatus. Our studies indicate infestations with a previously undescribed Chorioptes species.