Cetacean Morbillivirus Research Articles

Pathologic findings and causes of death in bottlenose dolphins Tursiops truncatus stranded along the Georgia coast, USA (2007-2013).

Between 2007 and 2013, before the 2013 cetacean morbillivirus outbreak, 26 fresh bottlenose dolphin carcasses were necropsied on the coast of Georgia, USA. Here, we present the pathological and microbiological findings associated with their most likely causes of death. The primary cause of death was determined in 25 individuals and included systemic bacterial infection (n = 7), verminous and bacterial bronchopneumonia (n = 5), drowning/entanglement (n = 5), disseminated histoplasmosis (n = 1), intestinal intussusception (n = 1), vegetative endocarditis (n = 1), meningitis (n = 1), necrotizing dermatitis (n = 1), disseminated angiomatosis (n = 1), emaciation (n = 1) and stingray spine trauma (n = 1). Histiocytic and eosinophilic bronchopneumonia associated with Halocerchus sp. infection was observed in 69% of the animals (18/26) and eosinophilic gastritis due to Anisakidae nematodes was found in 36% of the examined stomachs (8/22). Moderate to severe eosinophilic pancreatitis with fibrosis was observed in 4 animals infected with Brachycladiidae trematodes. Proliferative and ulcerative lymphoplasmacytic dermatitis was found in 5 animals and was considered to contribute to deteriorated health status in 2 calves. Pulmonary and lymph node angiomatosis were observed in 15 and 10 animals, respectively. In at least 2 animals, the concentration of polychlorinated biphenyls (PCBs) in the blubber exceeded 1500 µg g-1 of lipid. Bottlenose dolphins stranded on the Georgia coast have a wide range of inflammatory lesions associated with a variety of helminth, bacterial, and fungal pathogens. Some resident animals have also been exposed to high levels of PCB contamination, which could reduce host immunocompetence. Higher exposure to these or other pathogens could result in further decline in the health of resident and migrant dolphin populations in this region.

A novel real-time PCR to detect Cetacean morbillivirus in Atlantic cetaceans

Cetacean morbillivirus (CeMV, family Paramyxoviridae) is a re-emergent pathogen associated with severe epizootic outbreaks causing high mortality among cetaceans worldwide. Recently, CeMV caused an unusual mortality event of Guiana dolphins (Sotalia guianensis) in Brazil. Partial sequence of the viral phosphoprotein (P) gene showed that the Guiana dolphin morbillivirus (GDMV) might represent a new lineage of CeMV. This study aimed to develop a molecular technique to detect the most common CeMV strains known to circulate in the Atlantic Ocean: GDMV, Dolphin morbillivirus (DMV) and Pilot-whale morbillivirus (PWMV). A sensible real-time reverse transcription polymerase chain reaction (RT-qPCR) method based on intercalating dye, targeting the P gene was described. This assay successfully detected GDMV, PWMV and DMV from field samples. Its performance was compared to a RT-qPCR method that specifically detects GDMV. Both assays had high sensibility and excellent intra- and inter-assay reproducibility. A total of 109 field samples from 32 Guiana dolphins were screened for CeMV by conventional RT-PCR in parallel with the RT-qPCR assay. The detection rate increased from 32% to 60% by use of the novel RT-qPCR. The RT-qPCR assay described herein allows rapid and sensitive detection of Atlantic CeMV strains, and is potentially suitable for screening of CeMV globally.

Alpha- and gammaherpesviruses in stranded striped dolphins (Stenella coeruleoalba) from Spain: first molecular detection of gammaherpesvirus infection in central nervous system of odontocetes

BackgroundHerpesvirus infections in cetaceans have always been attributed to the Alphaherpesvirinae and Gammaherpesvirinae subfamilies. To date, gammaherpesviruses have not been reported in the central nervous system of odontocetes.Case presentationA mass stranding of 14 striped dolphins (Stenella coeruleoalba) occurred in Cantabria (Spain) on 18th May 2019. Tissue samples were collected and tested for herpesvirus using nested polymerase chain reaction (PCR), and for cetacean morbillivirus using reverse transcription-PCR. Cetacean morbillivirus was not detected in any of the animals, while gammaherpesvirus was detected in nine male and one female dolphins. Three of these males were coinfected by alphaherpesviruses. Alphaherpesvirus sequences were detected in the cerebrum, spinal cord and tracheobronchial lymph node, while gammaherpesvirus sequences were detected in the cerebrum, cerebellum, spinal cord, pharyngeal tonsils, mesenteric lymph node, tracheobronchial lymph node, lung, skin and penile mucosa. Macroscopic and histopathological post-mortem examinations did not unveil the potential cause of the mass stranding event or any evidence of severe infectious disease in the dolphins. The only observed lesions that may be associated with herpesvirus were three cases of balanitis and one penile papilloma.ConclusionsTo the authors’ knowledge, this is the first report of gammaherpesvirus infection in the central nervous system of odontocete cetaceans. This raises new questions for future studies about how gammaherpesviruses reach the central nervous system and how infection manifests clinically.

Transmission and Prevention of Wuhan Coronavirus Disease 2019 (COVID-19) under Minimum Sunspot Number

Porpoises, infected by Cetacean Morbillivirus from the feces of humpback whales in the East Sea, swam along the Yangtze River to reach Dongting Lake. Infected porpoises could be stranded and moved to Huanan Seafood Wholesale Market. Wuhan is low-lying and susceptible to flooding from the Yangtze River. Agricultural water in Hubei should prevent the harmful algal blooms for clean water. Sterilization by ultraviolet is recommended in air, water and confirmed patient with dialyzer to recover the Wuhan coronavirus disaster. The vaccine can be developed by culturing blood from CeMV infected porpoises in the Yangtze River or Dongting Lake, along with Wuhan coronavirus confirmed patient blood. Existing MMR Vaccine can be applied to cure the confirmed patient. CO2 emissions increased continuously with years (R2= 0.9497) causing high levels of UVB radiation on the Earth. Due to 11 years cycle of the sunspot number, there can be another dangerous outbreak at Dongting Lake with millions of migratory birds in China in coming years between 2030 and 2032.

Modelling cetacean morbillivirus outbreaks in an endangered killer whale population

The emergence of novel diseases represents a major hurdle for the recovery of endangered populations, and in some cases may even present the threat of extinction. In recent years, epizootics of infectious diseases have emerged as a major threat to marine mammal populations, particularly group-living odontocetes. However, little research has explored the potential consequences of novel pathogens in endangered cetacean populations. Here, we present the first study predicting the spread of infectious disease over the social network of an entire free-ranging cetacean population, the southern resident killer whale community (SRKW). Utilizing 5 years of detailed data on close contacts between individuals, we build a fine-scale social network describing potential transmission pathways in this population. We then simulate the spread of cetacean morbillivirus (CeMV) over this network. Our analysis suggests that the SRKW population is highly vulnerable to CeMV. The majority of simulations resulted in unusual mortality events (UMEs), with mortality rates predicted to be at least twice the recorded maximum annual mortality. We find only limited evidence that this population's social structure inhibits disease spread. Vaccination is not likely to be an efficient strategy for reducing the likelihood of UMEs, with over 40 vaccinated individuals (>50% of the population) required to reduce the likelihood of UMEs below 5%. This analysis highlights the importance of modelling efforts in designing strategies to mitigate disease, and suggests that populations with strong social preferences and distinct social units may still be highly vulnerable to disease outbreaks.

Prolonged gray wolf endangered species act listing fluctuation and policymaker response in the United States

The emergence of novel diseases represents a major hurdle for the recovery of endangered populations, and in some cases may even present the threat of extinction. In recent years, epizootics of infectious diseases have emerged as a major threat to marine mammal populations, particularly group-living odontocetes. However, little research has explored the potential consequences of novel pathogens in endangered cetacean populations. Here, we present the first study predicting the spread of infectious disease over the social network of an entire free-ranging cetacean population, the southern resident killer whale community (SRKW). Utilizing 5 years of detailed data on close contacts between individuals, we build a fine-scale social network describing potential transmission pathways in this population. We then simulate the spread of cetacean morbillivirus (CeMV) over this network. Our analysis suggests that the SRKW population is highly vulnerable to CeMV. The majority of simulations resulted in unusual mortality events (UMEs), with mortality rates predicted to be at least twice the recorded maximum annual mortality. We find only limited evidence that this population's social structure inhibits disease spread. Vaccination is not likely to be an efficient strategy for reducing the likelihood of UMEs, with over 40 vaccinated individuals (>50% of the population) required to reduce the likelihood of UMEs below 5%. This analysis highlights the importance of modelling efforts in designing strategies to mitigate disease, and suggests that populations with strong social preferences and distinct social units may still be highly vulnerable to disease outbreaks.

Pathologic findings and causes of death in southern right whales Eubalaena australis, Brazil.

Southern right whales Eubalaena australis (SRWs) migrate to southern Brazil for breeding and calving from June through November. Overall, there is scarce knowledge on health status and pathologic conditions in SRWs. We report the pathologic and molecular investigation results of 8 SRWs that were necropsied between 2010 and 2017 within a breeding and calving ground in Santa Catarina state, Brazil. The animals were of various ages (7 newborns/calves, 1 adult) and sex (3 females, 5 males). Five whales stranded dead; 3 stranded alive and died shortly after (n = 2) or were euthanized (n = 1). The causes of stranding and/or death were neonatal respiratory distress syndrome with meconium aspiration (n = 3) with concomitant congenital hepatopathy in one of them; trauma of unknown origin (n = 3), infectious renal and lung disease with presumed sepsis (n = 1), and euthanasia (n = 1). Three animals were PCR-positive for cetacean morbillivirus; one of them also had morbilliviral antigen in kidney via immunohistochemical analysis. These results, integrating novel findings and a published report, contribute to the pathology knowledge of this species.

Neurobrucellosis in a common bottlenose dolphin (Tursiops truncatus) stranded in the Canary Islands

BackgroundBrucella spp. isolation is increasingly reported in cetaceans, although associated pathologies, including lesions of the musculoskeletal and nervous systems, are less frequently described. Concerning the nervous system, Brucella sp. infection causing meningitis, meningoencephalitis or meningoencephalomyelitis have been extensively reported in striped dolphins (Stenella coeruleoalba), and less frequently in other cetacean species.Case presentationA juvenile female common bottlenose dolphin (Tursiops truncatus) was found stranded alive in Lanzarote (Canary Islands, Spain) in 2005, but died shortly after. On physical examination, the dolphin showed a moderate body condition and was classified as code 2 (fresh dead) at the time of necropsy. The main gross findings were severe multiorgan parasitism, thickened and congested leptomeninges, and (sero)fibrino-suppurative and proliferative arthritis of the shoulder joint. Histopathological examination revealed the distinct features of a sub-acute systemic disease associated with Cetacean Morbillivirus (CeMV) infection. However, brain lesions diverged from those reported in systemic CeMV infection. This led to suspect that there was a coinfecting pathogen, based on the characteristics of the inflammatory response and the lesion distribution pattern in the central nervous system. Brucella sp. was detected in the brain tissue by PCR and Brucella antigen was demonstrated by immunohistochemistry in the brain and shoulder joint lesions.ConclusionsThe zoonotic potential of marine mammal strains of Brucella has been demonstrated both in natural and laboratory conditions. In this study, PCR detected Brucella sp. in the brain of a common bottlenose dolphin stranded in the Canary Islands; the dolphin was also co-infected with CeMV. This is the first detection of Brucella sp. infection in a stranded cetacean in this archipelago. Therefore, we stress the importance of taking adequate measures during the handling of these species to prevent the transmissions of the infection to humans.

Marine Morbilliviruses: Diversity and Interaction with Signaling Lymphocyte Activation Molecules.

Epidemiological reports of phocine distemper virus (PDV) and cetacean morbillivirus (CeMV) have accumulated since their discovery nearly 30 years ago. In this review, we focus on the interaction between these marine morbilliviruses and their major cellular receptor, the signaling lymphocyte activation molecule (SLAM). The three-dimensional crystal structure and homology models of SLAMs have demonstrated that 35 residues are important for binding to the morbillivirus hemagglutinin (H) protein and contribute to viral tropism. These 35 residues are essentially conserved among pinnipeds and highly conserved among the Caniformia, suggesting that PDV can infect these animals, but are less conserved among cetaceans. Because CeMV can infect various cetacean species, including toothed and baleen whales, the CeMV-H protein is postulated to have broader specificity to accommodate more divergent SLAM interfaces and may enable the virus to infect seals. In silico analysis of viral H protein and SLAM indicates that each residue of the H protein interacts with multiple residues of SLAM and vice versa. The integration of epidemiological, virological, structural, and computational studies should provide deeper insight into host specificity and switching of marine morbilliviruses.

Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections.

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.

Molecular, serological, pathological, immunohistochemical and microbiological investigation of Brucella spp. in marine mammals of Brazil reveals new cetacean hosts.

Brucella-exposure and infection is increasingly recognized in marine mammals worldwide. To better understand the epidemiology and health impacts of Brucella spp. in marine mammals of Brazil, molecular (conventional PCR and/or real-time PCR), serological (Rose Bengal Test [RBT], Competitive [c]ELISA, Serum Agglutination Test [SAT]), pathological, immunohistochemical (IHC) and/or microbiological investigations were conducted in samples of 129 stranded or by-caught marine mammals (orders Cetartiodactyla [n=124], Carnivora [n=4] and Sirenia [n=1]). Previous serological tests performed on available sera of 27 of the 129 animals (26 cetaceans and one manatee), indicated 10 seropositive cetaceans. Conventional PCR and/or real-time PCR performed in cases with available organs (n=119) and/or blood or swabs (n=10) revealed 4/129 (3.1%) Brucella-infected cetaceans (one of them with positive serology; the remaining three with no available sera). Pathological, IHC and/or microbiological analyses conducted in PCR/real-time PCR and/or seropositive cases (n=13) revealed Brucella-type lesions, including meningitis/meningoencephalitis, pneumonia, necrotizing hepatitis, pericarditis and osteoarthritis in some of those animals, and positive IHC was found in all of them (excepting two live-stranded animals without available organs). Brucella spp. culture attempts were unsuccessful. Our results demonstrated exposure, asymptomatic, acute and chronic Brucella sp. infection in several cetacean species in the Brazilian coast, highlighting the role of this pathogen in stranding and/or death, particularly in Clymene dolphin (Stenella clymene) and short-finned pilot whale (Globicephala macrorhynchus) off Ceará State. Novel hosts susceptible to Brucella included the franciscana (Pontoporia blainvillei), the Guiana dolphin (Sotalia guianensis) and the spinner dolphin (Stenella longirostris). Additionally, three coinfection cases involving Brucella spp. and cetacean morbillivirus, Edwarsiella tarda and Proteus mirabilis were detected. To the best of our knowledge, this is the first long-term and large-scale survey of Brucella spp. in marine mammals of South America, widening the spectrum of susceptible hosts and geographical distribution range of this agent with zoonotic potential.

Cetacean morbillivirus: A Land-to-Sea Journey and Back?

Cetacean morbillivirus (CeMV), the most relevant pathogen impacting the health and conservation of several already threatened cetacean populations worldwide ( Van Bressem et al. 2014 ), has shown in recent years an apparently increased tendency to cross interspecies barriers ( Jo et al. 2018a ), thereby giving rise to disease and mortality outbreaks in free-ranging dolphins and whales ( Mazzariol et al. 2016 , 2017 ; Jo et al. 2018b ). Additional cases of infection have been also reported in aquatic mammals with a mixed aquatic-terrestrial ecology like common seals (Phoca vitulina) ( Mazzariol et al. 2013 ) and Eurasian otters (Lutra lutra) ( Padalino et al. 2019 ), increasing the overall concern and attention towards this Morbillivirus genus member. Within such context, the demonstrated ability of the dolphin morbillivirus (DMV) strain to utilize both dolphin and seal SLAM/CD150 as host cell receptors ( Jo et al. 2018b ) is biologically relevant and supports cross-species viral transmission events.

Comparative histopathologic and viral immunohistochemical studies on CeMV infection among Western Mediterranean, Northeast-Central, and Southwestern Atlantic cetaceans

Cetacean morbillivirus (CeMV) is a major natural cause of morbidity and mortality in cetaceans worldwide and results in epidemic and endemic fatalities. The pathogenesis of CeMV has not been fully elucidated, and questions remain regarding tissue tropism and the mechanisms of immunosuppression. We compared the histopathologic and viral immunohistochemical features in molecularly confirmed CeMV-infected Guiana dolphins (Sotalia guianensis) from the Southwestern Atlantic (Brazil) and striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) from the Northeast-Central Atlantic (Canary Islands, Spain) and the Western Mediterranean Sea (Italy). Major emphasis was placed on the central nervous system (CNS), including neuroanatomical distribution of lesions, and the lymphoid system and lung were also examined. Eleven Guiana dolphins, 13 striped dolphins, and 3 bottlenose dolphins were selected by defined criteria. CeMV infections showed a remarkable neurotropism in striped dolphins and bottlenose dolphins, while this was a rare feature in CeMV-infected Guiana dolphins. Neuroanatomical distribution of lesions in dolphins stranded in the Canary Islands revealed a consistent involvement of the cerebrum, thalamus, and cerebellum, followed by caudal brainstem and spinal cord. In most cases, Guiana dolphins had more severe lung lesions. The lymphoid system was involved in all three species, with consistent lymphoid depletion. Multinucleate giant cells/syncytia and characteristic viral inclusion bodies were variably observed in these organs. Overall, there was widespread lymphohistiocytic, epithelial, and neuronal/neuroglial viral antigen immunolabeling with some individual, host species, and CeMV strain differences. Preexisting and opportunistic infections were common, particularly endoparasitism, followed by bacterial, fungal, and viral infections. These results contribute to understanding CeMV infections in susceptible cetacean hosts in relation to factors such as CeMV strains and geographic locations, thereby establishing the basis for future neuro- and immunopathological comparative investigations.

Clinical signs in free-ranging Guiana dolphins Sotalia guianensis during a morbillivirus epidemic: case study in Sepetiba Bay, Brazil.

From November 2017 to March 2018, a cetacean morbillivirus (CeMV) outbreak caused an unprecedented mass mortality among Guiana dolphins Sotalia guianensis in Ilha Grande Bay and Sepetiba Bay, Rio de Janeiro, Brazil. Small boat surveys were conducted to document the behavior and clinical signs presented by diseased dolphins. We observed 5 abnormally behaving, disoriented Guiana dolphins on separate days, of which 1 died stranded and 2 sank. Signs of ataxia included difficulties with swimming and maintaining a course, balance and buoyancy. At least 40 other individuals were emaciated, and 10 photo-identified dolphins had miscellaneous skin lesions, some ulcerated. Labored breathing suggestive of airway obstruction was heard in several groups. These neurological, respiratory and cutaneous signs may comprise part of the clinical constellation of CeMV infection in dolphins. The combined threat of anthropogenic pressures and CeMV lethal disease is of concern for the survival of the Guiana dolphin population in Sepetiba Bay.

Examining receptor usage by the morbilliviruses: who, or what, is really at risk?

There are seven ‘established’ morbilliviruses: rinderpest (RPV), measles (MeV), small ruminant (PPRV), cetacean (CeMV), phocine (PDV), canine (CDV) and feline (FmoV) morbillivirus, the majority of which are thought to have narrow host ranges. The exception is CDV, which has been reported in almost all families of the order Carnivora, as well as non-human primates. Morbilliviruses enter cells through one of two proteinaceous receptors: signalling lymphocyte activation molecule F1 (SLAMF1), present on the surface of many immune cells; or Nectin-4, expressed on the basolateral side of various polarised epithelial cells. Given the close similarity of these viruses and their universal use of related receptors, there are realistic fears morbilliviruses may spill-over into naïve hosts, i.e. following eradication of RPV in cattle. This spill-over is not entirely unprecedented; PDV and MeV are thought to share common ancestors with CDV and RPV, respectively. To examine morbillivirus receptor usage and predict future spill-over and zoonotic transmission events, we have developed a high-throughput, quantifiable, cell-cell fusion assay. Effector cells, expressing the viral F and H glycoproteins as well as a split-luciferase reporter, are co-cultured with target cells expressing SLAMF1 or Nectin-4 receptors and the remaining half of the reporter. Upon functional receptor engagement the effector and target cells fuse, allowing cytoplasmic mixing and reconstitution of the reporter, a process which can be quantified. Using these assays we are investigating whether the receptor usage profile of morbilliviruses represents an important factor in spill-over transmission into new hosts.

Genome-wide association study of an unusual dolphin mortality event reveals candidate genes for susceptibility and resistance to cetacean morbillivirus.

Infectious diseases are significant demographic and evolutionary drivers of populations, but studies about the genetic basis of disease resistance and susceptibility are scarce in wildlife populations. Cetacean morbillivirus (CeMV) is a highly contagious disease that is increasing in both geographic distribution and incidence, causing unusual mortality events (UME) and killing tens of thousands of individuals across multiple cetacean species worldwide since the late 1980s. The largest CeMV outbreak in the Southern Hemisphere reported to date occurred in Australia in 2013, where it was a major factor in a UME, killing mainly young Indo‐Pacific bottlenose dolphins (Tursiops aduncus). Using cases (nonsurvivors) and controls (putative survivors) from the most affected population, we carried out a genome‐wide association study to identify candidate genes for resistance and susceptibility to CeMV. The genomic data set consisted of 278,147,988 sequence reads and 35,493 high‐quality SNPs genotyped across 38 individuals. Association analyses found highly significant differences in allele and genotype frequencies among cases and controls at 65 SNPs, and Random Forests conservatively identified eight as candidates. Annotation of these SNPs identified five candidate genes (MAPK8, FBXW11, INADL, ANK3 and ACOX3) with functions associated with stress, pain and immune responses. Our findings provide the first insights into the genetic basis of host defence to this highly contagious disease, enabling the development of an applied evolutionary framework to monitor CeMV resistance across cetacean species. Biomarkers could now be established to assess potential risk factors associated with these genes in other CeMV‐affected cetacean populations and species. These results could also possibly aid in the advancement of vaccines against morbilliviruses.

Evolutionary evidence for multi-host transmission of cetacean morbillivirus

Cetacean morbillivirus (CeMV) has emerged as the pathogen that poses the greatest risk of triggering epizootics in cetacean populations worldwide, and has a high propensity for interspecies transmission, including sporadic infection of seals. In this study, we investigated the evolutionary history of CeMV by deep sequencing wild-type viruses from tissue samples representing cetacean species with different spatiotemporal origins. Bayesian phylogeographic analysis generated an estimated evolutionary rate of 2.34 × 10−4 nucleotide substitutions/site/year and showed that CeMV evolutionary dynamics are neither host-restricted nor location-restricted. Moreover, the dolphin morbillivirus strain of CeMV has undergone purifying selection without evidence of species-specific mutations. Cell-to-cell fusion and growth kinetics assays demonstrated that CeMV can use both dolphin and seal CD150 as a cellular receptor. Thus, it appears that CeMV can readily spread among multiple cetacean populations and may pose an additional spillover risk to seals.

Cetacean morbillivirus in Southern Right Whales, Brazil.

Cetacean morbillivirus (CeMV) has caused repeated epizootics and interepizootic fatalities in a variety of cetacean species worldwide. Recently, a novel CeMV strain (GD-CeMV) was linked to a mass die-off of Guiana dolphins (Sotalia guianensis) in Brazil. Southern right whales (SRWs; Eubalaena australis) migrate to the southern Brazilian coast during austral winter and spring (June through November) for breeding and calving. Because unexplained high calf mortality rates have recurrently been documented in SRWs, we hypothesized they could be infected with CeMV. We developed a novel real-time RT-PCR method based on SYBR® GREEN for detection of CeMV and identified the virus in three out of five stranded SRWs from Santa Catarina state, Brazil. The partial sequences of the morbillivirus phosphoprotein gene suggest that the virus is similar to the GD-CeMV strain. Our results indicate CeMV can infect SRWs and should be considered in the differential aetiologic diagnosis of infectious diseases in this species. It also raises concern for potential conservation implications for this species in its main coastal breeding area off Southern Brazil.

Pyogranulomatous obliterative laryngotracheitis by Rhizopus arrhizus (syn. R. oryzae) in a free-ranging Atlantic spotted dolphin Stenella frontalis.

We report the gross and microscopic findings and molecular identification of fungal hyphate infection in a juvenile female Atlantic spotted dolphin Stenella frontalis found dead off Arguineguin, Gran Canaria (Canary Islands, Spain). On necropsy examination, the animal had a large cranial intrathoracic mass and multiple variably-sized nodules throughout the larynx and trachea that obliterated the lumen. Microscopically, the masses were composed of abundant pyogranulomatous inflammation with numerous fungal hyphae. These were pauciseptate (coenocytic) and had non-parallel walls, non-dichotomous irregular to right angle branching, and bulbous dilations. PCR analysis from these inflammatory foci yielded Rhizopus arrhizus (syn. R. oryzae). This fungal pathogen is often ascribed to opportunistic infections in immunosuppressed humans and animals. In the present case, a potential cause for immunosuppression was not identified; PCR analysis for cetacean morbillivirus was negative. Herein, we report the first confirmed case of R. arrhizus infection in a free-living Atlantic cetacean. These findings add to the body of knowledge on fungal disease in cetaceans in general and, in particular, in odontocetes, where respiratory involvement is common.

Genetic heterogeneity of dolphin morbilliviruses detected in the Spanish Mediterranean in inter-epizootic period

BackgroundIn the last 20 years, Cetacean Morbillivirus (CeMV) has been responsible for many die-offs in marine mammals worldwide, as clearly exemplified by the three dolphin morbillivirus (DMV) epizootics of 1990–1992, 2006–2008 and 2011 that affected Mediterranean striped dolphins (Stenella coeruleoalba). Systemic infection caused by DMV in the Mediterranean has been reported only during these outbreaks.ResultsWe report the infection of five striped dolphins (Stenella coeruleoalba) stranded on the Spanish Mediterranean coast of Valencia after the last DMV outbreak that ended in 2011. Animal 1 stranded in late 2011 and Animal 2 in 2012. Systemic infection affecting all tissues was found based on histopathology and positive immunohistochemical and polymerase chain reaction positive results. Animal 3 stranded in 2014; molecular and immunohistochemical detection was positive only in the central nervous system. Animals 4 and 5 stranded in 2015, and DMV antigen was found in several tissues. Partial sequences of the DMV phosphoprotein (P), nucleoprotein (N), and hemagglutinin (H) genes were identical for Animals 2, 3, 4, and 5, and were remarkably different from those in Animal 1. The P sequence from Animal 1 was identical to that of the DMV strain that caused the epizootic of 2011 in the Spanish Mediterranean. The corresponding sequence from Animals 2–5 was identical to that from a striped dolphin stranded in 2011 on the Canary Islands and to six dolphins stranded in northeastern Atlantic of the Iberian Peninsula.ConclusionsThese results suggest the existence of an endemic infection cycle among striped dolphins in the Mediterranean that may lead to occasional systemic disease presentations outside epizootic periods. This cycle involves multiple pathogenic viral strains, one of which may have originated in the Atlantic Ocean.