HISTOPATHOLOGY AND RISK FACTORS ASSOCIATED WITH NEOTROMBICULA MICROTI INFESTATION IN THE ENDANGERED AMARGOSA VOLE (MICROTUS CALIFORNICUS SCIRPENSIS).
The Amargosa vole (Microtus californicus scirpensis) is a profoundly endangered rodent found only in the Central Mojave Desert, Inyo County, California, US. In 2010, severe cases of trombiculiasis, caused by larval Neotrombicula microti mites, were discovered among voles and sympatric small mammals. We evaluated Amargosa voles and sympatric rodents for infestation with N. microti December 2011-November 2012 and evaluated histopathology of ear tissue from 13 actively N. microti-infested Amargosa voles and 10 Amargosa voles with no gross evidence of current or past infestation. Rodents with current infestation had mites visible on tissue, typically ear pinnae, whereas mites were not seen on rodents with presumptive past infestation, but some of these animals had gross tissue scarring and loss consistent with healing from infestation. Ears from infested voles had severe granulocytic and necrotizing dermatitis, most associated with stylostome fragments, whereas few lesions were present in grossly uninfested voles. There was no association between body condition and infestation or severity of lesions. Significantly more voles were infested (37%) with N. microti than sympatric rodents (3%), suggesting that sympatric rodents do not serve as an important source of N. microti exposure to voles. Although this chigger infestation was common and induced severe localized pathology, we did not detect a fitness cost to infestation and recommend further evaluation of the disease to discern its significance in this conservation context.
1  Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, 1 Shields Avenue, Davis, California 95616, USA.
Caitlin N
CN
Ott-Conn
2  California Animal Health and Food Safety Laboratory System, Davis Branch, University of California, Davis, 1 Shields Avenue, Davis, California 95616, USA.
Leslie W
LW
Woods
1  Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, 1 Shields Avenue, Davis, California 95616, USA.|3  Wildlife Investigations Lab, California Department of Fish and Wildlife, 1701 Nimbus Road Suite D, Rancho Cordova, California 95670, USA.
Deana L
DL
Clifford
4  California Department of Fish and Wildlife, 407 W Line Street, Bishop, California 93514, USA.|5  Current address: Los Angeles Department of Water and Power, 300 Mandich Street, Bishop, California 93514, USA.
Tammy
T
Branston
1  Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, 1 Shields Avenue, Davis, California 95616, USA.
Janet
J
Foley
D000818:Animals; D000835:Animals, Wild / Q000469:parasitology; D003411:Arvicolinae / Q000469:parasitology*; D002140:California; D004423:Ear / Q000469:parasitology / Q000473:pathology; D056727:Endangered Species; D005260:Female; D008297:Male; D012307:Risk Factors; D061350:Sympatry; D014323:Trombiculiasis / Q000209:etiology / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D014324:Trombiculidae
Amargosa vole; Microtus californicus scirpensis; Neotrombicula microti; auricular dermatitis; chiggers; trombiculiasis