First outbreak of cetacean morbillivirus in the South Atlantic: epidemiological context
Haydee A. Cunha, Elitieri Batista Santos Neto, Rafael R. Carvalho, Joana Ikeda, Katia R. Groch, Josue Díaz-Delgado, Leonardo Flach, Tatiana L. Bisi, Jose L. Catao-Dias, Alexandre F. Azevedo, José Lailson Brito Jr
International Whaling Commission
Cetacean morbillivirus (CeMV) has caused massive and cyclical mortalities in the North Atlantic and Mediterranean since the 1980’s. However, no epizootics had been recorded in the South Atlantic, until an unusual mortality event (UME) involving Guiana dolphins (Sotalia guianensis) began in Ilha Grande Bay, southeastern Brazil, in November 2017. In a four-month period, the UME spread to neighboring Sepetiba Bay and amounted to at least 263 deaths. Females had higher mortality rates during the UME, in contrast with historical mortality data from both bays that showed a 2:1 male to female death ratio. These results suggest that females were more vulnerable to morbilliviral infection. Herein, we discuss possible explanations for such sex-biased death pattern during the ongoing CeMV-UME and their implication for the conservation of endangered Guiana dolphins. We also hypothesize about the origin and spread of morbillivirus in the South Atlantic.