Epizootic of morbilliviral disease in common dolphins (Delphinus delphis ponticus) from the Black Sea

Forty-seven common dolphins (Delphinus delphis ponticus) were stranded on t he northern shores of the Black Sea between mid-July and early September 19 94, more than in previous or subsequent years. Two of the 47 dolphins were examined in detail to try to determine the cause of the increased stranding rate. Their lesions included broncho-interstitial pneumonia with type II e pithelial cell hyperplasia and multinucleate syncytial cells, neuronal necr osis, gliosis, and non-suppurative meningitis of the brain, necrotic stomat itis, gastroenteritis and cholangitis, and lymphoid depletion of the spleen and lymph nodes. The diseased tissues stained positive in an immunoperoxid ase test, using a polyclonal antiserum to measles virus as the primary anti body, and electron microscopy showed that they contained regularly-shaped i ntranuclear particles about 22 nm in diameter. They were positive by the po lymerase chain reaction (PCR) for the nucleoprotein gene of morbillivirus. However, there was no evidence of morbillivirus in frozen tissues either by virus isolation or by antigen capture ELISA The concentration of Sigma DDT S in the blubber of both dolphins was about 50 to 100 times higher than the levels in toothed cetaceans from the North Sea, North Atlantic Ocean, and Baltic Sea. The lesions were consistent with those found in other species w ith morbilliviral disease, and the positive immunoperoxidase test. PCR and electron microscopical examination confirmed a morbillivirus as the primary cause of these lesions.