Brucella sp. antibodies in polar bears from Svalbard and the Barents Sea

A prevalence of 5.4% of anti-Brucella sp. antibodies was found in plasma samples from 297 polar bears (Ursus maritimus) from Svalbard and the Barents Sea. Plasma was tested by the classical brucellosis tests Slow Agglutination of Wright (SAW), EDTA modified SAW and Rose Bengal test, as well as by an indirect Protein A ELISA. Only samples classified as positive in all tests were regarded as containing anti-Brucella sp. antibodies. A significant west to east increase in the proportion of bears with anti-Brucella sp. antibodies was found, with 3.6% (n = 253) at Svalbard (Spitsbergen, Nordaustlandet, Edgeøya, Barentsøya and Hopen), and 15.9% (n = 44) in the central Barents Sea. Anti-Brucella sp. antibodies were previously found in ringed seals (Phoca hispida) and harp seals (Phoca groenlandica) from the same geographical areas. The ringed seal is an important prey species for the Svalbard polar bear population, and may thus be a source of brucellosis for the bears. There are no indications of reproductive disorders caused by Brucella sp. or other infectious agents in our study polar bear population. Potential impacts of Brucella sp. exposure on individuals or the population are unknown.