SEROLOGICAL EVIDENCE OF MORBILLIVIRUS INFECTION IN POLAR BEARS (URSUS-MARITIMUS) FROM ALASKA AND RUSSIA

One-hundred-and-ninety-one samples of blood serum collected from 186 p olar bears (Ursus maritimus) between 1987 and 1992 were analysed for m orbillivirus antibodies, The samples were collected in the Bering, Chu kchi and East Siberian seas, Sixty-eight samples (35.6 per cent) had m orbillivirus antibody titres >5; the percentage of positive samples ra nged from 26.2 to 46.2 per cent from year to year. The proportions of adults, sub-adults and cubs which were seropositive were 43.9, 35.7 an d 37.9 per cent respectively, Some seropositive dams had seronegative young and some that a ere seronegative had seropositive young, One lit ter of two cubs, in which the dam was seronegative, had one seropositi ve and one seronegative cub, Seropositive bears occurred in all the ar eas from which the samples were collected but there was a significantl y greater incidence in the bears sampled in Russia. The high prevalenc e of seropositive bears over the period suggests that the bear morbill ivirus is endemic in these regions of the Arctic, but its source is un known.