Sarcoptic Mange in Black Bears (Ursus americanus) in Pennsylvania

At least three mite species cause mange in black bears (Ursus americanus), Demodex ursi, Ursicoptes americanus, and Sarcoptes scabiei. Since the early 1990s, there has been an increase in the number and geographic distribution... [ view full abstract ]

At least three mite species cause mange in black bears (Ursus americanus), Demodex ursi, Ursicoptes americanus, and Sarcoptes scabiei. Since the early 1990s, there has been an increase in the number and geographic distribution of severe mange in black bears in Pennsylvania. We evaluated several diagnostic assays for detection and identification of the mite(s) associated with these cases. We also examined the genetic diversity of mites collected from black bears and wild canids in Pennsylvania. Samples from 72 black bears with mange were examined and all had mites morphologically identified as S. scabiei. Sequence analysis of ITS-2 and cox1 gene confirmed mites were S. scabei. PCR testing of feces was uniformly negative. Using a commercial indirect ELISA, antibodies against S. scabiei were detected in most bears with clinical signs of mange but also rarely in cubs and adult bears with no outward signs of mange. Microscopic lesions from 40 bears with mange were consistent with lesions described in fox and dogs. Eighteen ITS-2 sequences were obtained from bears (n = 14), red fox (n = 2), and coyote (n = 2). The bear sequences were identical and canid sequences differed from bear sequences at a single nucleotide. Eighteen cox1 sequences obtained from bears represented seven unique haplotypes. Phylogenetic analysis of cox1 sequences revealed four clades, 1) a clade of mites of human origin from Panama, 2) a clade of human origin mites from Australia, 3) a clade of mites from rabbits in China, and 4) a large unresolved clade that included the remaining S. scabei sequences from various hosts and regions, including sequences from the bears from the current study. These data confirm the cause of mange in black bears in Pennsylvania is S. scabei and suggests that serologic testing may be useful for studying the epidemiology of this outbreak.