A Serosurvey of Multiple Pathogens in American Black Bears (Ursus americanus) in Pennsylvania, USA Indicates a Lack of Association with Sarcoptic Mange

Seroprevalence of Sarcoptes scabiei in Free-Ranging Black Bears (Ursus americanus) in Eastern North Carolina, USA

Recent sarcoptic mange epizootics have affected free-ranging black bears (Ursus americanus) in the northeastern US, but not in North Carolina. To determine whether black bears in eastern North Carolina have exposure to Sarcoptes scabiei, serum samples from hunter-harvested black bears (n=45) were collected and evaluated for antibodies using a commercial enzyme-linked immunosorbent assay previously validated in black bears. No dermal lesions consistent with sarcoptic mange were identified in the sampled bears. The seroprevalence among these asymptomatic bears was 18%, with no significant difference between sexes or association with age. This suggests that exposure to Sarcoptes scabiei occurs within the population, and highlights the importance of serosurveys in regions without a history of clinical mange.

Sarcoptic mange: An emerging panzootic in wildlife

Sarcoptic mange, a skin infestation caused by the mite Sarcoptes scabiei, is an emerging disease for some species of wildlife, potentially jeopardizing their welfare and conservation. Sarcoptes scabiei has a near-global distribution facilitated by its forms of transmission and use of a large diversity of host species (many of those with broad geographic distribution). In this review, we synthesize the current knowledge concerning the geographic and host taxonomic distribution of mange in wildlife, the epidemiological connections between species, and the potential threat of sarcoptic mange for wildlife conservation. Recent sarcoptic mange outbreaks in wildlife appear to demonstrate ongoing geographic spread, increase in the number of hosts and increased virulence. Sarcoptic mange has been reported in at least 12 orders, 39 families and 148 species of domestic and wild mammals, making it one of the most generalist ectoparasites of mammals. Taxonomically, the orders with most species found infested so far include Perissodactyla (67% species from the entire order), Artiodactyla (47%), and Diprotodontia (67% from this order). This suggests that new species from these mammal orders are likely to suffer cross-species transmission and be reported positive to sarcoptic mange as surveillance improves. We propose a new agenda for the study of sarcoptic mange in wildlife, including the study of the global phylogeography of S. scabiei, linkages between ecological host traits and sarcoptic mange susceptibility, immunology of individuals and species, development of control strategies in wildlife outbreaks and the effects of global environmental change in the sarcoptic mange system. The ongoing transmission globally and sustained spread among areas and wildlife species make sarcoptic mange an emerging panzootic in wildlife. A better understanding of sarcoptic mange could illuminate the aspects of ecological and evolutionary drivers in cross-species transmission for many emerging diseases.

Viruses in unexplained encephalitis cases in American black bears (Ursus americanus)

Viral infections were investigated in American black bears (Ursus americanus) from Nevada and northern California with and without idiopathic encephalitis. Metagenomics analyses of tissue pools revealed novel viruses in the genera Circoviridae, Parvoviridae, Anelloviridae, Polyomaviridae, and Papillomaviridae. The circovirus and parvovirus were of particular interest due to their potential importance as pathogens. We characterized the genomes of these viruses and subsequently screened bears by PCR to determine their prevalence. The circovirus (Ursus americanus circovirus, UaCV) was detected at a high prevalence (10/16, 67%), and the chaphamaparvovirus (Ursus americanus parvovirus, UaPV) was found in a single bear. We showed that UaCV is present in liver, spleen/lymph node, and brain tissue of selected cases by in situ hybridization (ISH) and PCR. Infections were detected in cases of idiopathic encephalitis and in cases without inflammatory brain lesions. Infection status was not clearly correlated with disease, and the significance of these infections remains unclear. Given the known pathogenicity of a closely related mammalian circovirus, and the complex manifestations of circovirus-associated diseases, we suggest that UaCV warrants further study as a possible cause or contributor to disease in American black bears.