Brucella Species Survey in Polar Bers (Urus martimus) of Northern Alaska

Todd M. O'Hara, University of Alaska Fairbanks
Darce Holcomb, University of Alaska Fair
Philip Elzer, Louisiana State University
Jessica Estepp, University of Southern Mississippi
Quinesha Perry, Louisiana State University
Sue Hagius, Louisiana State University
Cassandra Kirk, University of Alaska Fairbanks


We report on the presence of specific antibodies to Brucella spp and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003-2006 Based on numerous known stressors (e g, climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears Considering these changes, It is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways Brucella or specific antibodies to Brucella spp has been reported in marine mammals Various assays were used to elucidate the pathway or source of exposure (e g, "marine" vs "terrestrial" Brucella spp) of northern Alaska polar bears to Brucella spp The standard plate test (SPT) and the buffered Brucella antigen card test (BBA) were used for initial screening for antibodies specific to Brucella We then evaluated positive reactors (presence of serum antibody specific for Brucella spp) using immunoblots and competitive enzyme-linked immunosorbent assay (cELISA, based on pumped-derived Brucella spp antigen) Annual prevalence of antibody (BBA and SPT) for Brucella spp ranged from 6 8% to 18 5% over 2003-2006, with an overall prevalence of 10 2%. Prevalence of Brucella spp antibody did vary by age class Western blot analyses indicated 17 samples were positive for Brucella spp. antibody, of these, 13 were negative by marine (primped) derived Brucella antigen cELISA and four were positive by marine cELISA Oldie four samples positive for Brucella antibody by marine cELISA, three cross-reacted with Y enterocolitica and Brucella spp (one sample was Brucella negative and Y enterocolitica positive) It appears the polar bear antibody does not react with the antigens used on the marine cELISA assay, potentially indicating a terrestrial (nonpinniped) source of Brucella spp.