Epidemiological features of the first Unusual Mortality Event linked to cetacean morbillivirus in the South Atlantic (Brazil, 2017–2018)

• Published in: Marine Mammal Science
• Main Authors: Cunha, Haydée A., Santos‐Neto, Elitieri B., Carvalho, Rafael R., Ikeda, Joana M. P., Groch, Katia R., Díaz‐Delgado, Josué, Guari, Emi B., Brião, Juliana A., Oliveira, Raissa B., Flach, Leonardo, Bisi, Tatiana L., Catão‐Dias, José L., Azevedo, Alexandre F., Lailson‐Brito, José
• Other Authors: Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Fundação de Amparo à Pesquisa do Estado de São Paulo, Petrobras, Universidade do Estado do Rio de Janeiro
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: South Atlantic Ocean
• Online Access: http://dx.doi.org/10.1111/mms.12824; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12824; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mms.12824

Abstract Since the 1980s, cetacean morbillivirus (CeMV) has caused mass mortality events worldwide. However, no epizootics had been recorded in the South Atlantic, until an unusual mortality event (UME) linked to Guiana dolphin cetacean morbillivirus (GD‐CeMV) began in Ilha Grande Bay, southeastern Brazil, in November 2017. In a five‐month period, the UME spread to neighboring Sepetiba Bay and accounted for the death of at least 277 Guiana dolphins ( Sotalia guianensis ). Prevalence of morbillivirus positive dolphins, as estimated from RT‐PCR diagnostics, was 92.3% (24/26) in Ilha Grande Bay and 91.9% (57/62) in Sepetiba Bay. Females had higher mortality rates during the UME (1.5:1), in contrast with historical mortality data from both bays that showed a 2:1 male to female death ratio. Calf mortality rates also increased in both bays. These results suggest that females and calves were more vulnerable to morbilliviral infection. Herein, we discuss possible explanations for such sex‐biased death pattern during the UME and their implication for the conservation of endangered Guiana dolphins. We also speculate about the origin and spread of morbillivirus in the South Atlantic Ocean.