A morbillivirus antibody survey of Atlantic walrus, Narwhal and Beluga in Canada

A longitudinal serologic survey was conducted for morbillivirus antibodies in Atlantic walruses (Odobenus rosmarus rosmarus), narwhal (Monodon monocer os), and beluga (Delphinapterus leucas) from the Northwest Territories, Nun avut and the St. Lawrence estuary (Canada). Sixty-five of 131 (50%) walruse s sampled between 1984 and 1993 had detectable morbillivirus neutralizing a ntibodies. Positive walrus were identified from four of five Arctic samplin g sites, to as far back as 1984. Prevalence of morbillivirus neutralizing a ntibodies in walruses from Fore Basin ranged from a high of 76% (n = 21) in 1993 to a low of 22% (n = 28) in 1984. Limitations in sample acquisition m ay have produced underestimates for the 1984 data. There are no reports of clinical morbillivirus infection in walruses. Our results are consistent wi th the hypothesis that a morbillivirus similar or identical to phocine dist emper virus (PDV) has circulated among walrus populations of the eastern Ca nadian Arctic, at least since the early 1980s. No narwhal (n = 79) or belug a (n = 44.5) from Arctic waters were identified as having antibodies to dol phin morbillivirus (DMV) above the threshold serum dilution of log(2) 4. Al so, none of the beach-cast cetacean carcasses (n = 28) from the Gulf of St. Lawrence and the St. Lawrence estuary were positive for antibodies to DMV. This indicates that Gulf of St. Lawrence, St. Lawrence estuary, and Arctic cetaceans either have not been exposed to DMV or an antigenically related morbillivirus, or are not susceptible to infection.