Systematic beach monitoring as a health assessment tool: Cetacean morbillivirus under non-epizootic circumstances in stranded dolphins.

Cetacean morbillivirus (CeMV) was identified as the etiologic agent of several epizootic episodes worldwide. Most of these studies are based on unusual mortality events or identification of new viral strains. We investigated the occurrence of CeMV under non-epizootic circumstances at a world heritage in Southern Brazil by a combination of pathologic, immunohistochemical and molecular assays. From 325 stranded cetaceans, 40 were included. Guiana dolphin (Sotalia guianensis) was the most frequent species. Interstitial pneumonia and non-suppurative encephalitis were the main pathologic findings associated with CeMV infection. Intracytoplasmic immunolabelling anti-CeMV was observed mainly in lungs and lymph nodes. All samples were negative in reverse transcription polymerase chain reaction assay. Diagnosis of CeMV is challenging in areas where epizootic episodes have not been recorded and due to post-mortem changes. We observed a CeMV prevalence of 27.5%. The results described here increase the knowledge about CeMV under non-epizootic conditions in Brazil and worldwide.