Mass die-off of Caspian seals caused by canine distemper virus.
Thousands of Caspian seals (Phoca caspica) died in the Caspian Sea between April and August 2000. Seal samples were collected from Kazakhstan, Turkmenistan and Azerbaijan. Lesions characteristic of morbillivirus infection were found in tissue specimens from dead seals. Canine distemper virus infection was identified by serological examination, reverse transcriptase-polymerase chain reaction, and sequencing of selected P gene fragments. These results implicate canine distemper virus infection as the primary cause of death.