MORBILLIVIRUS INFECTION IN 2 SPECIES OF PILOT WHALES (GLOBICEPHALA SP) FROM THE WESTERN ATLANTIC

We report evidence of enzootic morbillivirus infection among long-finn ed, Globicephala melas, and short-finned, G. macrorhynchus, pilot whal es in the western Atlantic. A retrospective serologic survey, using fi ve morbilliviruses, was carried out on 99 G. melas from 14 stranding e vents between 1982 and 1993 and from 25 G. macrorhynchus stranded in 5 events between 1986 and 1994. A blood sample was also obtained from a n adult G. melas by-caught in the western North Atlantic. Tissues were collected from 24 G. melas and 15 G. macrorhynchus for histology and immunoperoxidase staining. Neutralizing antibody titers were found in 92 (92%) of 100 G. melas and 16 (64%) of 25 G. macrorhynchus, and tite rs were highest against cetacean morbilliviruses. Seroprevalence was s imilar between age classes and sexes. The earliest evidence of infecti on was in a G. melas that stranded in 1982. Stable antibody titers wer e observed in pilot whales under rehabilitation for up to eight months . Clinical disease consistent with morbillivirus pneumonia was detecte d in a G. melas calf. Immunoperoxidase staining confirmed that viral a ntigen was present in the lesions. We propose that enzootic infection in pilot whales is facilitated by population size, social structure, a nd migration patterns. Furthermore, through mixing with other odontoce tes, pilot whales could act as vectors through the Atlantic. Clinical morbillivirus infection may precipitate mass strandings of highly soci al odontocetes.