During November–December 2017, a mass die-off of Guiana dolphins (Sotalia guianensis) began in Rio de Janeiro, Brazil. Molecular and pathologic investigations on 20 animals indicated that cetacean morbillivirus played a major role. Our findings increase the knowledge on health and disease aspects of this endangered species.

Cetacean morbillivirus (CeMV; Paramyxoviridae) is the most significant pathogen of cetaceans worldwide. The novel “multi-host” Guiana dolphin ( Sotalia guianensis; GD)-CeMV strain is reported in South American waters and infects Guiana dolphins and southern right whales ( Eubalaena australis). This study aimed to describe the pathologic findings, GD-CeMV viral antigen distribution and detection by RT-PCR (reverse transcriptase polymerase chain reaction), and infectious comorbidities in 29 Guiana dolphins that succumbed during an unusual mass-mortality event in Rio de Janeiro state, Brazil, between November 2017 and March 2018. The main gross findings were lack of ingesta, pulmonary edema, ascites, icterus, hepatic lipidosis, multicentric lymphadenomegaly, as well as pneumonia, polyserositis, and multiorgan vasculitis caused by Halocercus brasiliensis. Microscopically, the primary lesions were bronchointerstitial pneumonia and multicentric lymphoid depletion. The severity and extent of the lesions paralleled the distribution and intensity of morbilliviral antigen. For the first time in cetaceans, morbilliviral antigen was detected in salivary gland, optic nerve, heart, diaphragm, parietal and visceral epithelium of glomeruli, vulva, and thyroid gland. Viral antigen within circulating leukocytes suggested this as a mechanism of dissemination within the host. Comorbidities included disseminated toxoplasmosis, mycosis, ciliated protozoosis, and bacterial disease including brucellosis. These results provide strong evidence for GD-CeMV as the main cause of this unusual mass-mortality event.

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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.

Many products contain dyes, such as fabrics. However, most of the industry-generated waste is improperly handled, which causes serious environmental problems for the bodies of water that receive textile effluents. This study aimed to analyze the effect of biosorbents and biosorption techniques on decolorizing the textile azo dye Acid Blue 29 in an aqueous solution employing pine sawdust. Pine sawdust is low-cost substrate with minor environmental impact. A toxicity test was performed with Lactuca sativa seeds to determine the LC 50 of the dye. Subsequently, a biosorption test was performed to determine the toxicity of the resulting solutions. We observed that biosorption is a very feasible technique for the discoloration of the solutions and promotes reduction in their toxicity.