Two morbilliviruses implicated in bottlenose dolphin epizootics

A systematic review on global zoonotic virus-associated mortality events in marine mammals

Marine mammals play a critical role as sentinels for tracking the spread of zoonotic diseases, with viruses being the primary causative factor behind infectious disease induced mortality events. A systematic review was conducted to document marine mammal mortality events attributed to zoonotic viral infections in published literature across the globe. This rigorous search strategy yielded 2883 studies with 88 meeting inclusion criteria. The studies spanned from 1989 to 2023, with a peak in publications observed in 2020. Most of the included studies were retrospective, providing valuable insights into historical trends. The United States (U.S.) reported the highest number of mortality events followed by Spain, Italy, Brazil and the United Kingdom. Harbor seals were the most impacted species, particularly in regions like Anholt, Denmark and the New England Coast, U.S. Analysis revealed six main viruses responsible for mortality events, with Morbillivirus causing the highest proportion of deaths. Notably, the occurrence of these viral events varied geographically, with distinct patterns observed in different regions. Immunohistochemistry emerged as the most employed detection method. This study underscores the importance of global surveillance efforts in understanding and mitigating the impact of viral infections on marine mammal populations, thereby emphasizing the necessity of collaborative One Health approaches to address emerging threats at the human-animal-environment interface. Additionally, the potential transfer of zoonotic viruses to aquatic organisms used in food production, such as fish and shellfish, highlights the broader implications for food safety, food security and public health.

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.

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

Background

Brucella 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 presentation

A 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.

Conclusions

The 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 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.

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.

INFECTIOUS DISEASE AND TOXICOLOGICAL MONITORING OF STRANDED PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDSI) IN COOK INLET AS SURROGATES FOR MONITORING ENDANGERED BELUGAS (DELPHINAPTERUS LEUCAS)

  Pacific harbor seals ( Phoca vitulina richardsi) and belugas ( Delphinapterus leucas ) eat many of the same prey species, occupy the same geographic area, and demonstrate site fidelity in Cook Inlet, Alaska. Although most direct research involving the critically endangered belugas is currently prohibited, studying harbor seals may provide important information about this beluga population. In recent years, harbor seal populations in Alaska have declined for unknown reasons. As part of its stranding program, the Alaska SeaLife Center (ASLC) managed 59 cases of live and dead stranded harbor seals from Cook Inlet between 1997 and 2011. Animals were screened for a variety of diseases and contaminants of concern. Animals were negative by serology to the following diseases: avian influenza, canine distemper virus, dolphin morbillivirus, porpoise morbillivirus, Leptospira canicola, L. grippotyphosa, L. pomona, Neospora caninum , Sarcocystis neurona , and Toxoplasma gondii . Positive titers were found against Brucella spp., phocine distemper virus, seal herpesvirus-1, L. bratislava, L. hardjo, and L. icterohemorrhagiae. All titers were stable or declining except in one animal with an increasing titer for seal herpesvirus-1. Fecal pathogen screenings identified normal flora as well as stable or declining low levels of potentially pathogenic and opportunistic bacteria, though most were of little concern for seal health. In most animals, toxicology screening showed that the majority of tested contaminants were below detectable limits. The level of evidence of exposure to pathogens of concern was low in harbor seals. Although the infectious disease burden and contaminant levels in belugas in Cook Inlet cannot be definitively determined without direct testing, pathogen and contaminant exposure is expected to be similar to that found in harbor seals in this region, as the harbor seals and belugas share the habitat and food resources.

Initial characterization of novel beaked whale morbillivirus in Hawaiian cetaceans

Cetacean morbillivirus (CeMV) is a causative factor in epizootics that have resulted in thousands of deaths throughout the Atlantic and Mediterranean since 1987, but less is known of its presence and significance in the Pacific. The first case of CeMV reported in Hawai'i was in a Longman's beaked whale that stranded in 2010. The initial CeMV sequence from this individual indicated the possibility of a novel strain. To address this, archived samples from cetaceans that stranded in Hawai'i between 1997 and 2014 were screened for CeMV. The beaked whale morbillivirus (BWMV) was detected in 15 individuals representing 12 different species (24% of Code 1 and 2 stranded cetaceans). The earliest detected case was a humpback whale that stranded in 1998. Sequence comparisons of a 2.2 kb sequence spanning the phosphoprotein (P) and nucleocapsid (N) genes strongly suggest that the BWMV represents a novel strain of CeMV present in Hawai'i and the Central Pacific. In contrast to recently reported isolates from Brazil and Australia that may represent a distinct clade, BWMV appears to be more closely related to known strains of CeMV (dolphin morbillivirus; porpoise morbillivirus; and pilot whale morbillivirus). Detection rates with repeat sampling of positive lymph nodes were between 2 and 61%, illustrating the extreme heterogeneity that can occur in affected tissues. Taken together, these results suggest that BWMV may be common and established in Hawaiian cetacean populations. BWMV will be important for understanding CeMV and health threats in the relatively understudied cetaceans of the Pacific.

Cetacean morbillivirus: current knowledge and future directions

We review the molecular and epidemiological characteristics of cetacean morbillivirus (CeMV) and the diagnosis and pathogenesis of associated disease, with six different strains detected in cetaceans worldwide. CeMV has caused epidemics with high mortality in odontocetes in Europe, the USA and Australia. It represents a distinct species within the Morbillivirus genus. Although most CeMV strains are phylogenetically closely related, recent data indicate that morbilliviruses recovered from Indo-Pacific bottlenose dolphins (Tursiops aduncus), from Western Australia, and a Guiana dolphin (Sotalia guianensis), from Brazil, are divergent. The signaling lymphocyte activation molecule (SLAM) cell receptor for CeMV has been characterized in cetaceans. It shares higher amino acid identity with the ruminant SLAM than with the receptors of carnivores or humans, reflecting the evolutionary history of these mammalian taxa. In Delphinidae, three amino acid substitutions may result in a higher affinity for the virus. Infection is diagnosed by histology, immunohistochemistry, virus isolation, RT-PCR, and serology. Classical CeMV-associated lesions include bronchointerstitial pneumonia, encephalitis, syncytia, and lymphoid depletion associated with immunosuppression. Cetaceans that survive the acute disease may develop fatal secondary infections and chronic encephalitis. Endemically infected, gregarious odontocetes probably serve as reservoirs and vectors. Transmission likely occurs through the inhalation of aerosolized virus but mother to fetus transmission was also reported.

Morbillivirus infection in free-ranging Atlantic bottlenose dolphins (Tursiops truncatus) from the Southeastern United States: seroepidemiologic and pathologic evidence of subclinical infection

From 2003 to 2007, sera (n=234) from free-ranging Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting two southeast Atlantic estuarine regions, the Indian River Lagoon (IRL), FL and Charleston, SC (CHS) were tested for antibodies to cetacean morbilliviruses as part of a multidisciplinary study of individual and population health. Positive morbillivirus titers were found on initial capture in 12 of 122 (9.8%) IRL dolphins in the absence of an epizootic. All CHS dolphins were seronegative. Positive fluctuating morbillivirus titers and seroconversion were found in IRL dolphins. Seropositivity was detected in dolphins 8-13 years of age as well as in dolphins that were alive during the 1987-1988 epizootic. During the study period, pathologic and immunohistochemical findings from stranded IRL dolphins (n=14) did not demonstrate typical morbillivirus-associated lesions or the presence of morbillivirus antigen. The findings suggest that morbillivirus infections are occurring in the absence of widespread mortality in IRL dolphins.

The vitamin D3 transcriptomic response in skin cells derived from the Atlantic bottlenose dolphin

The Atlantic bottlenose dolphin has attracted attention due to the evident impact that environmental stressors have taken on its health. In order to better understand the mechanisms linking environmental health with dolphin health, we have established cell cultures from dolphin skin as in vitro tools for molecular evaluations. The vitamin D3 pathway is one mechanism of interest because of its well established chemopreventative and immunomodulatory properties in terrestrial mammals. On the other hand, little is known of the physiological role of this molecule in aquatic animals. 1,25-dihydroxyvitamin D3 (1,25D3), the bioactive and hormonal form of vitamin D3, exerts its biological function by binding to the vitamin D receptor (VDR), a ligand-activated regulator of gene transcription. Therefore, we investigated the transcriptomic changes induced by 1,25D3 administration in dolphin skin cells. Identification of specific genes activated by 1,25D3 has provided clues to the physiological function of the vitamin D3 pathway in the dolphin. We found that exposure of the cells to 1,25D3 upregulated transactivation of a vitamin D-sensitive promoter. cDNA microarray analysis, using a novel dolphin array, identified specific gene targets within this pathway, and real-time PCR (qPCR) confirmed the enhanced expression of select genes of interest. These transcriptional changes correlated with an increase in VDR levels. This is the first report of the presence and activation of the vitamin D3 pathway in a marine mammal, and our experimental results demonstrate a number of similarities to terrestrial animals. Conservation of this pathway in the Atlantic bottlenose dolphin is consistent with the importance of nonclassic functions of vitamin D3, such as its role in innate immunity, similar to what has been demonstrated in other mammals.

Host-virus specificity of morbilliviruses predicted by structural modeling of the marine mammal SLAM, a receptor

Signaling lymphocyte activation molecule (SLAM) is thought to be a major cellular receptor for high-host specificity morbilliviruses, which cause devastating and highly infectious diseases in mammals. We determined the sequences of SLAM cDNA from five species of marine mammal, including two cetaceans, two pinnipeds and one sirenian, and generated three-dimensional models to understand the receptor-virus interaction. Twenty-one amino acid residues in the immunoglobulin-like V domains of the SLAMs were shown to bind the viral protein. Notably, the sequences from pinnipeds and dogs were highly homologous, which is consistent with the fact that canine distemper virus was previously shown to cause a mass die-off of seals. Among these twenty-one residues, eight (63, 66, 68, 72, 84, 119, 121 and 130) were shared by animal groups susceptible to a particular morbillivirus species. This set of residues appears to determine host-virus specificity and may be useful for risk estimation for morbilliviruses.

Morbillivirus and pilot whale deaths, Mediterranean Sea

An outbreak of a lethal morbillivirus infection of long-finned pilot whales occurred in the Mediterranean Sea from the end of October 2006 through April 2007. Sequence analysis of a 426-bp conserved fragment of the morbillivirus phosphoprotein gene indicates that the virus is more closely related to dolphin morbillivirus than to pilot whale morbillivirus.

Sequence of the nucleocapsid gene and genome and antigenome promoters for an isolate of porpoise morbillivirus

We have determined the first complete sequence of the nucleocapsid (N) gene of the porpoise morbillivirus (PMV) as well as the genome leader and trailer sequences which encode the genome and antigenome promoters, respectively. The PMV N gene is 1686 nucleotides long with a single open reading frame (ORF) encoding a protein of 523 amino acids with a predicted molecular weight of 57.39kDa. The nucleotide sequence of the N gene shows the closest identity (89%) to that of another cetacean morbillivirus, dolphin morbillivirus (DMV). Lower degrees of identity were found with the other members of the morbilliviruses genus; 67% identity to PDV and RPV, 68% to PPRV, 69% to CDV and 70% to MV. The distance from the 3' end of the genome up to the start of the N ORF is 107 nucleotides, identical to that found in all other morbilliviruses, and encompasses the genome promoter (GP) sequence. This promoter shows the same regions of conservation as found in other morbilliviruses with repeated CXXXXX motifs at positions 79-84, 85-90, and 91-96, the same bi-partite promoter arrangement found in many paramyxoviruses. The antigenome promoter (AGP) shows a similar arrangement, indicating a high degree of conservation in these functionally important regions.

Involvement of morbilliviruses in the pathogenesis of demyelinating disease

Two members of the morbillivirus genus of the family Paramyxoviridae, canine distemper virus (CDV) and measles virus (MV), are well-known for their ability to cause a chronic demyelinating disease of the CNS in their natural hosts, dogs and humans, respectively. Both viruses have been studied for their potential involvement in the neuropathogenesis of the human demyelinating disease multiple sclerosis (MS). Recently, three new members of the morbillivirus genus, phocine distemper virus (PDV), porpoise morbillivirus (PMV) and dolphin morbillivirus (DMV), have been discovered. These viruses have also been shown to induce multifocal demyelinating disease in infected animals. This review focuses on morbillivirus-induced neuropathologies with emphasis on aetiopathogenesis of CNS demyelination. The possible involvement of a morbillivirus in the pathogenesis of multiple sclerosis is discussed.

A DNA vaccine against dolphin morbillivirus is immunogenic in bottlenose dolphins

The immunization of exotic species presents considerable challenges. Nevertheless, for facilities like zoos, animal parks, government facilities and non-profit conservation groups, the protection of valuable and endangered species from infectious disease is a growing concern. The rationale for immunization in these species parallels that for human and companion animals; to decrease the incidence of disease. The U.S. Navy Marine Mammal Program, in collaboration with industry and academic partners, has developed and evaluated a DNA vaccine targeting a marine viral pathogen - dolphin morbillivirus (DMV). The DMV vaccine consists of the fusion (F) and hemagglutinin (H) genes of DMV. Vaccine constructs (pVR-DMV-F and pVR-DMV-H) were evaluated for expression in vitro and then for immunogenicity in mice. Injection protocols were designed for application in Atlantic bottlenose dolphins (Tursiops truncatus) to balance vaccine effectiveness with clinical utility. Six dolphins were inoculated, four animals received both pDMV-F and pDMV-H and two animals received a mock vaccine (vector alone). All animals received an inoculation week 0, followed by two booster injections weeks 8 and 14. Vaccine-specific immune responses were documented in all four vaccinated animals. To our knowledge, this is the first report of pathogen-specific immunogenicity to a DNA vaccine in an aquatic mammal species.

Evaluation of cetacean and sirenian cytologic samples

Cytology is a fundamental part of marine mammal veterinary medicine that is involved in preventive medicine programs in captive animals and in the health assessment of wild populations. Marine mammals often exhibit few clinical signs of disease; thus, the cost-effective and widely accessible nature of cytologic sampling renders it one of the most important diagnostic procedures with these species. Many of these mammals are endangered, protected, and located in developing nations in which resources may be scarce. This article can be used as a field guide to advise a veterinarian, biologist, or technician working with cetaceans or sirenians. A simplistic cost-effective staining technique is used, which is ideal for situations in which funds, facilities, or time may be a limiting factor in clinical practice.

Henipaviruses: emerging paramyxoviruses associated with fruit bats

Two related, novel, zoonotic paramyxoviruses have been described recently. Hendra virus was first reported in horses and thence humans in Australia in 1994; Nipah virus was first reported in pigs and thence humans in Malaysia in 1998. Human cases of Nipah virus infection, apparently unassociated with infection in livestock, have been reported in Bangladesh since 2001. Species of fruit bats (genus Pteropus) have been identified as natural hosts of both agents. Anthropogenic changes (habitat loss, hunting) that have impacted the population dynamics of Pteropus species across much of their range are hypothesised to have facilitated emergence. Current strategies for the management of henipaviruses are directed at minimising contact with the natural hosts, monitoring identified intermediate hosts, improving biosecurity on farms, and better disease recognition and diagnosis. Investigation of the emergence and ecology of henipaviruses warrants a broad, cross-disciplinary ecosystem health approach that recognises the critical linkages between human activity, ecological change, and livestock and human health.

Discovery and characterization of the 1918 pandemic influenza virus in historical context

The 2005 completion of the entire genome sequence of the 1918 H1N1 pandemic influenza virus represents both a beginning and an end. Investigators have already begun to study the virus in vitro and in vivo to better understand its properties, pathogenicity, transmissibility and elicitation of host responses. Although this is an exciting new beginning, characterization of the 1918 virus also represents the culmination of over a century of scientific research aiming to understand the causes of pandemic influenza. In this brief review we attempt to place in historical context the identification and sequencing of the 1918 virus, including the alleged discovery of a bacterial cause of influenza during the 1889-1893 pandemic, the controversial detection of 'filter-passing agents' during the 1918-1919 pandemic, and subsequent breakthroughs in the 1930s that led to isolation of human and swine influenza viruses, greatly influencing the development of modern virology.

Discovery and Characterization of the 1918 Pandemic Influenza Virus in Historical Context

The 2005 completion of the entire genome sequence of the 1918 H1N1 pandemic influenza virus represents both a beginning and an end. Investigators have already begun to study the virus in vitro and in vivo to better understand its properties, pathogenicity, transmissibility and elicitation of host responses. Although this is an exciting new beginning, characterization of the 1918 virus also represents the culmination of over a century of scientific research aiming to understand the causes of pandemic influenza. In this brief review we attempt to place in historical context the identification and sequencing of the 1918 virus, including the alleged discovery of a bacterial cause of influenza during the 1889–1893 pandemic, the controversial detection of ‘filter-passing agents’ during the 1918–1919 pandemic, and subsequent breakthroughs in the 1930s that led to isolation of human and swine influenza viruses, greatly influencing the development of modern virology.

Emerging henipaviruses and flying foxes - Conservation and management perspectives

Wildlife populations are affected by a series of emerging diseases, some of which pose a significant threat to their conservation. They can also be reservoirs of pathogens that threaten domestic animal and human health. In this paper, we review the ecology of two viruses that have caused significant disease in domestic animals and humans and are carried by wild fruit bats in Asia and Australia. The first, Hendra virus, has caused disease in horses and/or humans in Australia every five years since it first emerged in 1994. Nipah virus has caused a major outbreak of disease in pigs and humans in Malaysia in the late 1990s and has also caused human mortalities in Bangladesh annually since 2001. Increased knowledge of fruit bat population dynamics and disease ecology will help improve our understanding of processes driving the emergence of diseases from bats. For this, a transdisciplinary approach is required to develop appropriate host management strategies that both maximise the conservation of bat populations as well as minimise the risk of disease outbreaks in domestic animals and humans.

Morbillivirus infections in aquatic mammals: a brief overview

Since 1987, at least eight morbillivirus infection (MI) epidemics have caused mass mortality of several free-living pinniped and cetacean populations around the world. The responsible agents, all belonging to the genus Morbillivirus (family Paramyxoviridae), have been characterized as either "canine distemper virus" strains, infecting pinnipeds, or as three new morbilliviruses, namely "phocid (phocine) distemper virus" , "porpoise morbillivirus" and "dolphin morbillivirus" . The last two agents are currently gathered under the common denomination of "cetacean morbillivirus". At post-mortem examination, a commonly occurring macroscopic lesion is represented by more or less severe bilateral pneumonia, with consolidation, congestion and oedema of both lungs, which fail to collapse. Histologically, a non-suppurative broncho-interstitial pneumonia, characterized by type II pneumocyte hyperplasia and by formation of endobronchial, endobronchiolar and endoalveolar "Warthin-Finkeldey type" syncytia, as well as a multifocal, non-suppurative encephalitis, associated with a severe and generalized lymphoid tissue depletion, are common pathological findings. Furthermore, eosinophilic viral inclusions are often detected, at both the intracytoplasmic and intranuclear level, within bronchial and bronchiolar epithelial, pulmonary syncytial, neuronal and other cell types. These inclusions, along with lymphoid and other cellular elements, are often found to be immunohistochemically positive for morbillivirus antigen. Among the still debated, or even controversial issues regarding MI in sea mammals, the one related to the origin of their causative agents is of particular concern. Another intriguing issue regards the synergistic effects, if any, associated with chronic exposure to a number of environmental pollutants, such as organochlorines and heavy metals. In fact, it is also unknown whether and how these chemicals contribute towards modulating the pathogenic and pathogenetic activity primarily displayed by sea mammal morbilliviruses.

Emerging diseases: a global threat

A growing and globalizing threat of emerging and re-emerging diseases is best addressed through reliance on rapid detection, diagnosis, and containment. The efficiency and success of this approach depends on intricate networking and collaboration among all stakeholders including intergovernmental and nongovernmental organizations and specialized agencies in the developed and developing countries. Such cooperation, while focusing on eliminating a growing threat, also helps avoid duplication of effort and improves use of scarce financial resources. This review provides a summary of the problem of emerging/re-emerging diseases and the effort being directed at controlling the threat. Opportunities are identified for a more coordinated approach to addressing the problem.

Serum antibody levels against select bacterial pathogens in Atlantic bottlenose dolphins, Tursiops truncatus, from Beaufort NC USA and Charleston Harbor, Charleston, SC, USA

Concern over the emergence of zoonotic diseases in marine organisms is growing. In response to this concern, this study set out to measure antibody activities against bacterial pathogens in Atlantic bottlenose dolphins, Tursiops truncatus, from the coastal estuaries of NC and SC, USA. Individuals from Charleston SC harbor, a heavily industrialized shipping harbor estuary, and from Beaufort NC, a non-shipping estuary, were examined. Purified IgG was obtained from pooled sera using ammonium sulfate precipitation steps and protein-G procedures, which was then used to generate a panel of IgG-specific monoclonal antibodies. Two of these antibodies, mAbs BB-10-2 (IgG1) and BB-32-2 (IgG2b), were then used to determine total serum IgG concentrations using a sandwich capture ELISA. Circulating IgG levels were variable between individuals and between the two pods. MAb BB-10-2 was then used in an indirect ELISA to determine serum antibody activities against several common marine bacteria as well as the human pathogens E. coli and E. coli strain 0157:H7, Vibrio parahemolyticus, V. vulnificus, V. cholerae, Mycobacteria marinum, M. fortuitum, and M. chelonae. The highest antibody activities were against mycobacteria, two of which are zoonotic pathogens. Males had the highest antibody activities, thus suggesting low cell-mediated immunity against intracellular pathogens in these individuals. T-cell proliferation in response to Con-A, an indicator of cell-mediated immune function, was then measured in the Beaufort population. Males had the lowest proliferation responses, however a negative correlation between antibody activities and T-cell proliferation in individuals could not be established for either of the Mycobacteria species. Overall, antibody activities against all bacteria, including innocuous species such as V. anguillarum, V. natrigens, and M. xenopi were highly variable between individual dolphins and the two pods, with some animals exhibiting very high activities. These studies suggests that dolphin populations should be monitored by following the health and seroprevalence of pathogens of interest in select individual animals over time.

Central giant cell granuloma of the palate; unusual localisation in a five year old child

The central giant cell granuloma of the maxillo-mandibular region is a relatively uncommon lesion (3.5%-0.1%). Essentially, it occurs in the second decade of life and it is mainly located in the mandibular region. The female/male ratio is 3:1. The authors present an unusual localisation of central giant cell granuloma in a five year old child's maxillary bone. After a surgical curettage of the lesion, an eighteen months follow-up examination did not show any recurrence.

Shipping and the spread of infectious salmon anemia in Scottish aquaculture

Long-distance transport of pathogens plays a critical role in the emergence of novel diseases. Shipping is a major contributor to such transport, and the role of ships in spreading disease has been recognized for centuries. However, statistical confirmation of pathogen spread by shipping is usually impractical. We present evidence of invasive spread of infectious salmon anemia in the salmon farms of Scotland and demonstrate a link between vessel visits and farm contamination. The link is associated with vessels moving fish between sites and transporting harvest, but not with vessels delivering food or involved in other work.

An insight into the epidemiology of dolphin morbillivirus worldwide

Serum samples from 288 cetaceans representing 25 species and originating from 11 different countries were collected between 1995 and 1999 and examined for the presence of dolphin morbillivirus (DMV)-specific antibodies by an indirect ELISA (iELISA) (N = 267) or a plaque reduction assay (N = 21). A total of 35 odontocetes were seropositive: three harbour porpoises (Phocoena phocoena) and a common dolphin (Delphinus delphis) from the Northeastern (NE) Atlantic, a bottlenose dolphin (Tursiops truncatus) from Kent (England), three striped dolphins (Stenella coeruleoalba), two Risso's dolphins (Grampus griseus) and a bottlenose dolphin from the Mediterranean Sea, one common dolphin from the Southwest (SW) Indian Ocean, three Fraser's dolphins (Lagenodelphis hosei) from the SW Atlantic, 18 long-finned pilot whales (Globicephala melas) and a bottlenose dolphin from the SW Pacific as well as a captive bottlenose dolphin (Tursiops aduncus) originally from Taiwan. The presence of morbillivirus antibodies in 17 of these animals was further examined in other iELISAs and virus neutralization tests. Our results indicate that DMV infects cetaceans worldwide. This is the first report of DMV-seropositive animals from the SW Indian, SW Atlantic and West Pacific Oceans. Prevalence of DMV-seropositives was 85.7% in 21 pilot whales from the SW Pacific and both sexually mature and immature individuals were infected. This indicates that DMV is endemic in these animals. The same situation may occur among Fraser's dolphins from the SW Atlantic. The prevalence of DMV-seropositives was 5.26% and 5.36% in 19 common dolphins and 56 harbour porpoise from the NE Atlantic, respectively, and 18.75% in 16 striped dolphins from the Mediterranean. Prevalence varied significantly with sexual maturity in harbour porpoises and striped dolphins; all DMV-seropositives being mature animals. The prevalence of seropositive harbour porpoise and striped dolphins appeared to have decreased since previous studies. These data suggest that DMV is not endemic within these populations, that they are losing their humoral immunity against the virus and that they may be vulnerable to new epidemics.

Influenza RNA not detected in archival brain tissues from acute encephalitis lethargica cases or in postencephalitic Parkinson cases

Encephalitis lethargica (EL) was a mysterious epidemic. temporally associated with the 1918 Spanish influenza pandemic. Numerous symptoms characterized this disease, including headache, diplopia, fever, fatal coma, delirium, oculogyric crisis, lethargy, catatonia, and psychiatric symptoms. Many patients who initially recovered subsequently developed profound, chronic parkinsonism. The etiologic association of influenza with EL is controversial. Five acute EL autopsies and more than 70 postencephalitic parkinsonian autopsies were available in the Armed Forces Institute of Pathology (AFIP) tissue repository. Two of these 5 acute EL cases had histopathologic changes consistent with that diagnosis. The remaining 3 cases were classified as possible acute EL cases as the autopsy material was insufficient for detailed histopathologic examination. RNA lysates were prepared from 29 CNS autopsy tissue blocks from the 5 acute cases and 9 lysates from blocks containing substantia nigra from 2 postencephalitic cases. RNA recovery was assessed by amplification of beta-2-microglobulin mRNA and 65% of the tissue blocks contained amplifiable RNA. Reverse transcription-polymerase chain reaction (RT-PCR) for influenza matrix and nucleoprotein genes was negative in all cases. Thus, it is unlikely that the 1918 influenza virus was neurotropic and directly responsible for the outbreak of EL.

Molecular genetic evidence of a novel morbillivirus in a long-finned pilot whale (Globicephalus melas)

A long-finned pilot whale with morbilliviral disease was stranded in New Jersey. An immunohistochemical stain demonstrated morbilliviral antigen. Reverse transcriptase-polymerase chain reaction for morbillivirus P and N genes was positive. Novel sequences most closely related to, but distinct from, those of dolphin and porpoise morbilliviruses suggest that this virus may represent a third member of the cetacean morbillivirus group.

Central giant cell granuloma of the palate; unusual localisation in a five year old child

The central giant cell granuloma of the maxillo-mandibular region is a relatively uncommon lesion (3.5%-0.1%). Essentially, it occurs in the second decade of life and it is mainly located in the mandibular region. The female/male ratio is 3:1. The authors present an unusual localisation of central giant cell granuloma in a five year old child's maxillary bone. After a surgical curettage of the lesion, an eighteen months follow-up examination did not show any recurrence.

Advanced laboratory techniques at the Armed Forces Institute of Pathology applicable to diagnosis and research in dermatology

The Armed Forces Institute of Pathology (AFIP) is well known for providing expert pathology in many specialties and educational courses for civilian and military personnel. Some of the departments at the AFIP have also developed expertise in various advanced laboratory techniques for diagnosis and research that are applicable to dermatology and are not available at most medical centers.

Morbillivirus infections in aquatic mammals

Morbillivirus infections which were not documented in aquatic mammals until 1988, have caused at least five epizootics in these species during the last 10 years. Affected populations include European harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) in 1998, Baikal seals (Phoca siberica) in Siberia from 1987-1988, striped dolphins (Stenella coeruleoalba) in the Mediterranean Sea from 1990-1992 and bottlenose dolphins (Tursiops truncatus) along the eastern coast of the United States from 1987-1988 and in the Gulf of Mexico from 1993-1994. Clinical signs and lesions in affected animals were similar to those of canine distemper. Lesions were mainly seen in lung, central nervous and lymphoid tissues and included formation of intranuclear and intracytoplasmic inclusion bodies. Syncytia were commonly found in lung and lymphoid tissues of cetaceans but not of pinnipeds. Antigenic and molecular biological studies indicate that a newly discovered morbillivirus, termed phocine distemper virus, and canine distemper virus were responsible for recent pinniped epizootics; cetacean die-offs were caused by strains of a second, newly recognized cetacean morbillivirus. Serological evidence of morbillivirus infection has been identified in a broad range of marine mammal populations and recent epizootics probably resulted from transfer of virus to immunologically-naive populations.

Serosurvey of Toxoplasma gondii in North Atlantic marine mammals by the use of agglutination test employing whole tachyzoites and dithiothreitol

Serum samples from North Atlantic populations of harp seal, Phoca groenlandica (n = 316), ringed seal, Phoca hispida (n = 48), hooded seal, Cystophora cristata (n = 78), and minke whale, Balaenoptera acutorostrata (n = 202), were tested for Toxoplasma gondii-specific IgG. The modified agglutination test (MAT) was slightly modified to be more user-friendly by replacing the 0.2 M 2-mercaptoethanol with 10 mM dithiothreitol. No positive samples were found at 1:40 dilution.

Serological evidence of morbillivirus infection in small cetaceans from the Southeast Pacific

The presence of morbillivirus-specific serum antibodies was examined by an indirect enzyme linked immunosorbent assay (iELISA) and virus neutralization tests in serum samples from 30 dusky dolphins (Lagenorhynchus obscurus), 8 long-snouted common dolphins (Delphinus capensis), 2 inshore and 6 offshore bottlenose dolphins (Tursiops truncatus) and 20 Burmeister's porpoises (Phocoena spinipinnis) taken in fisheries off central Peru in 1993-1995. The sera from six dusky dolphins, one common dolphin and three offshore bottlenose dolphins were positive on a coat of dolphin morbillivirus (DMV) antigen in the iELISA. Several of these sera were also positive when tested against peste des petits ruminants and rinderpest virus antigen. Porpoise morbillivirus and/or DMV neutralizing antibodies were detected in the sera of two bottlenose and three dusky dolphins that reacted positively with DMV antigen in iELISA and also in the sera of one common, one dusky and one bottlenose dolphin that were negative in the iELISA. These results strongly suggest that viruses closely related, or identical, to the cetacean morbillivirus present in the North Atlantic and the Mediterranean Sea infect several species of Delphinidae of the Southeastern Pacific. No convincing morbillivirus-specific antibody positive reactions were detected in the sera from either the Burmeister's porpoises or the inshore bottlenose dolphins.

Histologic, immunohistochemical, and polymerase chain reaction studies of bottlenose dolphins from the 1987-1988 United States Atlantic coast epizootic

Tissues from 95 bottlenose dolphins (Tursiops truncatus) that died during the 1987-1988 US Atlantic coast epizootic and 11 bottlenose dolphins that died along the Atlantic coast prior to 1987 were examined histologically and immunohistochemically. Polymerase chain reaction (PCR) testing was performed on 36 of the epizootic and all of the pre-1987 cases. Epizootic cases had syncytia and rare intranuclear and intracytoplasmic inclusion bodies within lung, lymph node, and spleen. Lymphoid depletion was present in lymph node, spleen, and gut-associated lymphoid tissue of epizootic cases. Pre-1987 cases did not have these pulmonary and lymphoid lesions. A larger percentage of epizootic than pre-1987 cases had bacterial and/or fungal infections (primarily pneumonias), pulmonary and lymphoid tissue histiocytosis, mucocutaneous ulcers, and evidence of negative energy balance. Immunohistochemically, 49/95 (52%) epizootic dolphins were positive for morbilliviral antigen. Morbilliviral antigen was detected in lung, lymph node, spleen, thymus, skin, tongue, esophagus, liver, pancreas, gastrointestinal tract, urinary bladder, oviduct, and mammary gland by immunohistochemistry. PCR testing identified morbilliviral RNA in 35/36 (97%) epizootic cases tested. Neither morbilliviral antigen nor morbilliviral RNA were detected in pre-1987 cases. Histologic, immunohistochemical, and PCR results provide strong evidence that morbillivirus infection was the primary cause of the 1987-1988 bottlenose dolphin epizootic.