Cetacean morbillivirus in odontocetes stranded along the central California coast, USA, 2000–15

Effects of cetacean morbillivirus (CeMV) on dolphins vary from causing epidemics to subclinical infections. The former have been documented in the North Atlantic Ocean and Mediterranean Sea but not in the North Pacific Ocean, and the reasons for this are unknown. To explore the distribution of this virus in areas that have not experienced epidemics, we reviewed evidence for morbilliviral infection in odontocetes stranded along the California coast, US from 2000–15. Nine of 212 animals examined histolog-ically had lesions compatible with morbilliviral infection, and 11 were tested for CeMV via reverse transcriptase-PCR. One striped dolphin (Stenella coeruleoalba) was PCR positive, and the sequenced product was most closely related to sequences in two strains found in cetaceans in Hawaii. This study suggests that CeMV may be a cause of morbidity and a rare contributor to mortality in cetaceans stranding along the California coast. Additional work is needed to understand CeMV distribution and host species susceptibility in this region.