Surveillance for Dirofilaria spp. in American Black Bears (Ursus americanus) in Pennsylvania, 2018-2020
Open Access
- Author:
- Mazzatosta, Alia
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Justin D Brown, Thesis Supervisor
Robert John Vansaun, Thesis Honors Advisor - Keywords:
- Dirofilaria ursi
American black bear
Dirofilaria - Abstract:
- Dirofilaria ursi is a filarial nematode of bears, including American black bears (Ursus americanus), grizzly bears (Ursus arctos), and Asiatic black bears (Ursus thibetanus), that is vectored by black flies (Simuliidae). Clinical disease associated with D. ursi infection has not been reported in bears. Infection with D. ursi in bears can be detected by examining the subcutis and body cavity for adult nematodes or the blood for microfilaria. Surveillance based on detection of adults can underestimate infection in a population because of the highly variable anatomic location of the worms. Consequently, surveillance for D. ursi in this study was performed by screening blood for microfilaria. Blood smears from 129 black bears from Pennsylvania were examined, and 33 (25.6%) were found to contain microfilaria morphologically consistent with Dirofilaria spp. Other than bears that had sarcoptic mange, none of the positive bears had any reported overt signs of disease or lesions. Age, sex, and season did not have a significant effect on black bears being positive for Dirofilaria spp. (p > .05). Black bears that had sarcoptic mange were significantly less likely to be positive for microfilaria than bears without mange (p < 0.05). The results of this study indicate Dirofilaria spp. infection is common in black bears in Pennsylvania, but is not associated with disease. This data is consistent with previous surveys conducted in black bears in the Upper Midwest. Future studies are needed to further characterize epidemiologic patterns of Dirofilaria spp. infection in black bears, define associations between other microorganisms (e.g. Wolbachia and Sarcoptes scabiei), and determine the zoonotic potential of this common nematode of bears.