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21 April 2022 HISTOLOGIC LESIONS IN PLACENTAS OF NORTHERN FUR SEALS (CALLORHINUS URSINUS) FROM A POPULATION WITH HIGH PLACENTAL PREVALENCE OF COXIELLA BURNETII
Rachel Conway, Colleen Duncan, Robert A. Foster, Gilbert J. Kersh, Stephen Raverty, Tom Gelatt, Chad Frank
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Abstract

Coxiella burnetii is an intracellular bacterial pathogen that can be associated with significant reproductive disease or acute mortality in livestock and wildlife. A novel marine mammal–associated strain of C. burnetii has been identified in pinnipeds of the northwestern Pacific Ocean. Little is known about C. burnetii infection in regard to reproductive success or population status. Our objective was to characterize the severity and extent of histologic lesions in 117 opportunistically collected placentas from presumed-normal northern fur seals (Callorhinus ursinus) in July 2011 on St. Paul Island, Alaska, US, where a high placental prevalence of C. burnetii had been reported. Sections were examined by histology and immunohistochemistry and impression smears with modified acid-fast stain. The nature and frequency of histologic changes were compared with target COM1 PCR-confirmed C. burnetii positive and negative placentas. Overall, histologic changes were similar to placental lesions described in aborting ruminants; however, changes were variable within and between placentas. Vasculitis and occasional intracellular bacteria were seen only in C. burnetii PCR-positive placentas. Dystrophic mineralization, edema, and inflammation were seen in PCR-positive and negative placentas, although they were statistically more common in PCR-positive placentas. Results suggest that C. burnetti and associated pathologic changes are multifocal and variable in placentas from these presumably live-born pups. Therefore, multiple sections of tissue from different placental areas should be examined microscopically, and screened by PCR, to ensure accurate diagnosis as the genomes per gram of placenta may not necessarily represent the severity of placental disease. These limitations should inform field biologists, diagnosticians, and pathologists how best to screen and sample for pathogens and histopathology in marine mammal placental samples.

© Wildlife Disease Association 2022
Rachel Conway, Colleen Duncan, Robert A. Foster, Gilbert J. Kersh, Stephen Raverty, Tom Gelatt, and Chad Frank "HISTOLOGIC LESIONS IN PLACENTAS OF NORTHERN FUR SEALS (CALLORHINUS URSINUS) FROM A POPULATION WITH HIGH PLACENTAL PREVALENCE OF COXIELLA BURNETII," Journal of Wildlife Diseases 58(2), 333-340, (21 April 2022). https://doi.org/10.7589/JWD-D-21-00037
Received: 29 March 2021; Accepted: 9 November 2021; Published: 21 April 2022
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KEYWORDS
Callorhinus ursinus
Coxiella burnetii
histopathology
northern fur seal
placenta
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