title: Morbillivirus and Toxoplasma exposure and association with hematological parameters for southern Beaufort Sea polar bears: potential response to infectious agents in a sentinel species.
abstract: Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear's status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1-2 year olds least likely to be seropositive and bears aged 5-7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.
authors.affiliation: Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA. cmkirk@alaska.edu
authors.forename: Cassandra M
authors.initials: CM
authors.lastname: Kirk
authors.forename: Steven
authors.initials: S
authors.lastname: Amstrup
authors.forename: Rhonda
authors.initials: R
authors.lastname: Swor
authors.forename: Darce
authors.initials: D
authors.lastname: Holcomb
authors.forename: Todd M
authors.initials: TM
authors.lastname: O'Hara
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D001110:Arctic Regions; D015415:Biomarkers / Q000097:blood; D017753:Ecosystem; D005260:Female; D016015:Logistic Models; D008297:Male; D018103:Morbillivirus / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D014122:Toxoplasma / Q000276:immunology*; D001503:Ursidae / Q000097:blood / Q000469:parasitology* / Q000821:virology*
chemical_list: D000913:Antibodies, Protozoan; D000914:Antibodies, Viral; D015415:Biomarkers