Detection and molecular characterization of Ursicoptes americanus in Georgia, USA black bears (Ursus americanus): Clinical presentations, prevalence, and phylogenetic analysis

Abstract

Ursicoptes americanus is a follicular mite that can cause ursicoptic mange in bear species; however, its biology, epidemiology, and clinical significance remain poorly understood. First described in the 1970s from a captive American black bear (Ursus americanus) in Kansas, USA, this mite has since been reported sporadically in both captive and free-ranging black bears, predominately in the western United States. This study aimed to detect and characterize U. americanus in Georgia black bears, assess clinical presentations, estimate prevalence across distinct subpopulations, and analyze phylogenetic relationships with related mites. In August 2022, Georgia Department of Natural Resources (GADNR) submitted the carcass of a black bear from Pickens County to the Southeastern Cooperative Wildlife Disease Study (SCWDS), and a skin scrape revealed the first confirmed detection of U. americanus in Georgia. Following this discovery, three additional cases were identified, prompting an expanded surveillance effort across Georgia's three geographically distinct black bear subpopulations (north, central, and south). Skin scrapings from 56 bears collected between 2022 and 2024 were examined for mites and subjected to molecular analysis. U. americanus was detected in bears with a diversity of clinical presentations, ranging from apparently healthy to mild and moderate dermatologic lesions. These efforts uncovered an overall apparent prevalence of 10.7 % (6/56) in Georgia black bears, challenging the assumption that U. americanus is associated solely with debilitating mange. Instead, these results suggest a broader clinical spectrum and a more widespread distribution than previously thought. Molecular characterization of the mitochondrial 16S rRNA, nuclear 28S rDNA and cytochrome c oxidase subunit I (COI) genes revealed close associations to other avian and mammalian mite species in the Parvorder Psoroptidia, as well as relatively low genetic diversity of mites between different sampled bear populations. Collectively, these clinical, epidemiologic, and molecular data represent one of the most comprehensive assessments of U. americanus to date. Moving forward, U. americanus should be included in differential diagnoses when alopecia or crusted lesions are observed in bears, even in mild cases. Ongoing surveillance is critical as sarcoptic mange, caused by the mite Sarcoptes scabiei, continues to impact black bear populations across eastern North America.

Keywords: Audycoptic mange; Bear mange; Molecular characterization; Parasite; Wildlife; den dandruff.