Characterization of Cetacean Morbillivirus in Humpback Whales, Brazil.

Cetacean morbillivirus is an etiologic agent associated with strandings of live and dead cetacean species occurring sporadically or as epizootics worldwide. We report 2 cases of cetacean morbillivirus in humpback whales (Megaptera novaeangliae) in Brazil and describe the anatomopathological, immunohistochemical, and molecular characterization findings in the specimens.

Short-Finned Pilot Whale Strandings Associated with Pilot Whale Morbillivirus, Brazil.

Cetacean morbillivirus (CeMV) causes illness and death in cetaceans worldwide; the CeMV strains circulating in the Southern Hemisphere are poorly known. We detected a pilot whale CeMV strain in 3 short-finned pilot whales (Globicephala macrorhynchus) stranded in Brazil during July-October 2020. Our results confirm this virus circulates in this species.

A South American Mouse Morbillivirus Provides Insight into a Clade of Rodent-Borne Morbilliviruses.

Morbilliviruses are negative-sense single-stranded monosegmented RNA viruses in the family Paramyxoviridae (order Mononegavirales). Morbilliviruses infect diverse mammals including humans, dogs, cats, small ruminants, seals, and cetaceans, which serve as natural hosts. Here, I report the identification and characterization of novel viruses detected in public RNAseq datasets of South American long-haired and olive field mice. The divergent viruses dubbed Ratón oliváceo morbillivirus (RoMV) detected in renal samples from mice collected from Chile and Argentina are characterized by an unusually large genome including long intergenic regions and the presence of an accessory protein between the F and H genes redounding in a genome architecture consisting in 3'-N-P/V/C-M-F-hp-H-L-5'. Structural and functional annotation, genetic distance, and evolutionary insights suggest that RoMV is a member of a novel species within genus Morbillivirus tentatively named as South American mouse morbillivirus. Phylogenetic analysis suggests that this mouse morbillivirus is closely related to and clusters into a monophyletic group of novel rodent-borne morbilliviruses. This subclade of divergent viruses expands the host range, redefines the genomic organization and provides insights on the evolutionary history of genus Morbillivirus.

First detection of Feline morbillivirus infection in white-eared opossums (Didelphis albiventris, Lund, 1840), a non-feline host.

Feline Morbillivirus (FeMV) was first detected in 2012 in domestic cats from Hong Kong and was found to be associated with tubulointerstitial nephritis and chronic kidney disease. In subsequent studies in other countries, FeMV was detected in asymptomatic cats. However, it is not clear whether FeMV plays a role as a pathogen in the kidney diseases of cats, and other epidemiological data are still unknown. To date, studies have reported the presence of FeMV exclusively in domestic cats. This study is the first molecular detection of the FeMV RNA associated with pathological and immunohistochemical findings in a synanthropic marsupial, the white-eared opossum (Didelphis albiventris), inhabiting peri-urban areas of north-central Parana, Southern Brazil. Molecular techniques identified the viral RNA in the lungs and kidneys. Histopathologic evaluation of these tissues revealed interstitial pneumonia in the lungs with lymphocytic nephritis and tubular necrosis in the kidneys. Immunohistochemistry assays detected positive intralesional immunoreactivity to N protein of FeMV within the lungs and kidneys. A FeMV opossum strain was isolated in Crandell Rees feline kidney lineage cells, resulting in syncytia formation and cell death. Therefore, these results support the ability of FeMV to infect other mammal species and reinforce the possibility of the opossum to be a disseminator of this virus among domestic and wild animals.

Systematic beach monitoring as a health assessment tool: Cetacean morbillivirus under non-epizootic circumstances in stranded dolphins.

Cetacean morbillivirus (CeMV) was identified as the etiologic agent of several epizootic episodes worldwide. Most of these studies are based on unusual mortality events or identification of new viral strains. We investigated the occurrence of CeMV under non-epizootic circumstances at a world heritage in Southern Brazil by a combination of pathologic, immunohistochemical and molecular assays. From 325 stranded cetaceans, 40 were included. Guiana dolphin (Sotalia guianensis) was the most frequent species. Interstitial pneumonia and non-suppurative encephalitis were the main pathologic findings associated with CeMV infection. Intracytoplasmic immunolabelling anti-CeMV was observed mainly in lungs and lymph nodes. All samples were negative in reverse transcription polymerase chain reaction assay. Diagnosis of CeMV is challenging in areas where epizootic episodes have not been recorded and due to post-mortem changes. We observed a CeMV prevalence of 27.5%. The results described here increase the knowledge about CeMV under non-epizootic conditions in Brazil and worldwide.

Cetacean morbillivirus in Humpback whales' exhaled breath.

The humpback whale (HW; Megaptera novaeangliae) population that seasonally resides along the Brazilian coast concentrates in the Abrolhos Bank (Bahia and Espírito Santo states) for breeding during austral winter and spring. Cetacean morbillivirus (CeMV, Paramyxoviridae family) is currently one of the most significant biological threats to cetaceans worldwide with high infection and mortality rates. CeMV is pleiotropic yet it has special tropism for the respiratory, lymphoid and nervous system and is primarily transmitted by the aerogenous route. A new lineage of CeMV, the Guiana dolphin morbillivirus (GDMV), is known to affect cetaceans off Brazil. GDMV was first detected in a Guiana dolphin (Sotalia guianensis) stranded in the Abrolhos Bank region, in 2010. In addition to pathologic examinations on stranded HW, pathogen survey of free-ranging HW may provide valuable insight into the epidemiology of diseases. We hypothesized that HW in the Brazilian breeding ground could be exposed to CeMV. Thus, in the present study, we investigated the presence of CeMV in exhaled breath condensates (EBC) of HW in the Abrolhos Bank. Overall, 73 samples of EBC from 48 groups of HW were collected during the breeding seasons of 2011 (n = 16) and 2012 (n = 57). One sample failed to have the reference gene amplified and was excluded from the study. CeMV was detected by a RT-qPCR method in 2 EBC samples, representing 2 whale groups. Phylogenetic analysis of partial morbillivirus phosphoprotein gene showed 100% homology to GDMV. Our results show that HW in Brazil are infected by CeMV with a relative prevalence of 4.3% (2/47) and demonstrate the suitability of using EBC and RT-qPCR as a non-invasive tool for CeMV survey in free-ranging whales. This pioneer study provides scientific basis for non-invasive CeMV monitoring of HW, suggests HW may play a role in the dynamics of CeMV and raises concern for potential conservation implications for this species.

High genetic diversity of paramyxoviruses infecting domestic cats in Western Brazil.

Feline morbillivirus was discovered in 2012 in cats from Hong Kong, and it was initially found to be associated with chronic kidney disease. Although subsequent molecular surveys showed a common occurrence in cat populations from distinct countries, there were controversial results regarding the relationship between viral shedding through urine and reduced kidney function. In this study, 276 domestic cats of diverse origins from Western Brazil had their urine evaluated for the presence of paramyxoviral RNA by reverse transcription seminested PCR and direct sequencing. Additionally, a selected Brazilian feline morbillivirus strain was isolated in Crandell Rees feline kidney cells, and a nearly complete genome sequence was obtained. To assess the kidney function of all cats, serum biochemistry screening and standard urinalysis were performed. Our results revealed a relatively high paramyxovirus-positive rate (34.7%) in the evaluated cats although there was not a statistical association between the shedding of viral RNA through urine and kidney disease. Direct sequencing of partial fragments of the L gene demonstrated high genetic diversity among strains detected in cats in this study, since both feline morbillivirus RNA and feline paramyxovirus RNA were frequently shed in urine. Phylogenetic reconstruction based on partial amino acid sequences of the L gene showed that Brazilian feline paramyxovirus strains were genetically diverse since they grouped into two distinct subclusters; one subcluster contained three strains identified in Germany, while the second contained Japanese strain 163, which was recently classified in the Jeilongvirus genus of the Paramyxoviridae family. In contrast, the Brazilian feline morbillivirus strain FeMV/BR_Boni, herein characterized by nearly complete genome sequencing, was classified in the Morbillivirus genus with other strains previously identified as genotype 1. In conclusion, urinary excretion of diverse paramyxoviral RNA is frequent in cats of different origins from Western Brazil, but viral infection is not related to altered kidney function.

Identification of Novel Feline Paramyxoviruses in Guignas (Leopardus guigna) from Chile.

The family of paramyxoviruses has received growing attention as several new species have been identified recently, notably two different clusters in domestic cats, designated as feline morbillivirus (FeMV) and feline paramyxovirus (FPaV). Their phylogenetic origin and whether wild felids also harbor these viruses are currently unknown. Kidney samples from 35 guignas (Leopardus guigna), a wild felid from Chile, were investigated for paramyxoviruses using consensus-RT-PCR. In addition, thirteen serum samples of guignas were screened for the presence of FeMV-specific antibodies by an immunofluorescence assay (IFA). Viral RNA was detected in 31% of the kidney samples. Phylogenetic analyses revealed two well-supported clusters, related to isolates from domestic cats, rodents and bats. No significant histopathology changes were recorded in infected guignas. Serology identified two samples which were positive for FeMV-specific antibodies. Our study highlights the diversity of paramyxovirus infections in felids with special emphasis on guignas from Chile.

Cetacean Morbillivirus Infection in a Killer Whale (Orcinus orca) from Brazil.

We provide pathological, immunohistochemical and molecular evidence of cetacean morbillivirus (CeMV) infection in a live-stranded adult female killer whale (Orcinus orca), which stranded alive in Espírito Santo State, Brazil, in 2014. Although attempts were made to release the animal, it stranded again and died. The main pathological findings were severe pulmonary oedema, pleural petechiation, multifocal, lymphoplasmacytic meningoencephalitis and leptomeningomyelitis with perivascular cuffing and gliosis, chronic lymphocytic bronchointerstitial pneumonia and multicentric lymph node and splenic lymphoid depletion. Other pathological findings were associated with the 'live-stranding stress response'. Immunohistochemical analysis revealed multifocal morbilliviral antigen in neurons and astrocytes, and in pneumocytes, histiocytes and leukocytes in the lung. CeMV was detected by a novel reverse transcriptase polymerase chain reaction method in the brain and kidney. Phylogenetic analysis of part of the morbillivirus phosphoprotein gene indicates that the virus is similar to the Guiana dolphin (Sotalia guianensis) morbillivirus strain, known to affect cetaceans along the coast of Brazil. To the authors' knowledge, this is the first report of morbillivirus disease in killer whales.

The Pathology of Cetacean Morbillivirus Infection and Comorbidities in Guiana Dolphins During an Unusual Mortality Event (Brazil, 2017-2018).

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.

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.

Comparative Immunopathology of Cetacean morbillivirus Infection in Free-Ranging Dolphins From Western Mediterranean, Northeast-Central, and Southwestern Atlantic.

Cetacean morbillivirus (CeMV; Paramyxoviridae) causes epizootic and interepizootic fatalities in odontocetes and mysticetes worldwide. Studies suggest there is different species-specific susceptibility to CeMV infection, with striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus), and Guiana dolphins (Sotalia guianensis) ranking among the most susceptible cetacean hosts. The pathogenesis of CeMV infection is not fully resolved. Since no previous studies have evaluated the organ-specific immunopathogenetic features of CeMV infection in tissues from infected dolphins, this study was aimed at characterizing and comparing immunophenotypic profiles of local immune responses in lymphoid organs (lymph nodes, spleen), lung and CNS in CeMV-molecularly (RT-PCR)-positive cetaceans from Western Mediterranean, Northeast-Central, and Southwestern Atlantic. Immunohistochemical (IHC) analyses targeted molecules of immunologic interest: caspase 3, CD3, CD20, CD57, CD68, FoxP3, MHCII, Iba1, IFNγ, IgG, IL4, IL10, lysozyme, TGFß, and PAX5. We detected consistent CeMV-associated inflammatory response patterns. Within CNS, inflammation was dominated by CD3+ (T cells), and CD20+ and PAX5+ (B cells) lymphocytes, accompanied by fewer Iba1+, CD68+, and lysozyme+ histiocytes, mainly in striped dolphins and bottlenose dolphins. Multicentric lymphoid depletion was characterized by reduced numbers of T cells and B cells, more pronounced in Guiana dolphins. Striped dolphins and bottlenose dolphins often had hyperplastic (regenerative) phenomena involving the aforementioned cell populations, particularly chronically infected animals. In the lung, there was mild to moderate increase in T cells, B cells, and histiocytes. Additionally, there was a generalized increased expression of caspase 3 in lymphoid, lung, and CNS tissues. Apoptosis, therefore, is believed to play a major role in generalized lymphoid depletion and likely overt immunosuppression during CeMV infection. No differences were detected regarding cytokine immunoreactivity in lymph nodes, spleen, and lung from infected and non-infected dolphins by semiquantitative analysis; however, there was striking immunoreactivity for IFNγ in the CNS of infected dolphins. These novel results set the basis for tissue-specific immunophenotypic responses during CeMV infection in three highly susceptible delphinid species. They also suggest a complex interplay between viral and host's immune factors, thereby contributing to gain valuable insights into similarities, and differences of CeMV infection's immunopathogenesis in relation to body tissues, CeMV strains, and cetacean hosts.

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.

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.

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.

Guiana Dolphin Unusual Mortality Event and Link to Cetacean Morbillivirus, Brazil.

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.

First report of feline morbillivirus in South America.

Feline morbillivirus was first identified in healthy and diseased stray cats captured in Hong Kong. Recently, it was demonstrated that the virus circulates within cat populations in Japan, Italy, Germany, and the USA. Importantly, an association between feline morbillivirus infection and chronic kidney disease was suggested by histological analysis of kidney tissue of infected cats. The aim of this study was to verify the presence and examine the genetic diversity of feline morbilliviruses associated with infections of domestic cats in Brazil. Seventeen cats without clinical manifestations of urinary tract diseases from a multi-cat household and 35 random client-owned cats admitted to the Teaching Veterinary Hospital for a variety of reasons were evaluated for paramyxoviral infection and the presence of uropathy. A fragment of the paramyxoviral L gene was amplified from urine samples using a reverse transcription semi-nested PCR assay. For the first time, we detected a feline morbillivirus strain that was genetically related to viral strains previously characterized in Japan in urine samples from cats in South America, in Brazil. This together with the recent description of feline morbillivirus identification within cat populations in the USA, suggests a possible widespread distribution of this viral agent on the American continent. Our data demonstrated feline morbillivirus RNA shedding mostly in the urine of cats without clinical, laboratorial, or ultrasonographic signs of urinary tract diseases. In contrast to previously published findings that associated feline morbillivirus infection with chronic kidney disease, we did not observe a clear relationship between feline morbillivirus RNA shedding in urine and kidney disease in the cats evaluated.

Coinfection by Cetacean morbillivirus and Aspergillus fumigatus in a juvenile bottlenose dolphin (Tursiops truncatus) in the Gulf of Mexico.

A recently deceased juvenile male bottlenose dolphin (Tursiops truncatus) was found floating in the Gulf of Mexico, off Sand Key in Clearwater, Florida. At autopsy, we identified pneumonia and a focus of malacia in the right cerebrum. Cytologic evaluation of tissue imprints from the right cerebrum revealed fungal hyphae. Fungal cultures of the lung and brain yielded Aspergillus fumigatus, which was confirmed by amplification of a portion of the fungal nuclear ribosomal internal transcribed spacer 2 region sequence. Microscopic pulmonary lesions of bronchiolar epithelial cell syncytia with intracytoplasmic and intranuclear inclusions within bronchiolar epithelial cells were suggestive of Cetacean morbillivirus (CeMV) infection. The occurrence of CeMV infection was supported by positive immunohistochemical staining for morbillivirus antigen. CeMV detection was confirmed by amplification and sequencing a portion of the morbilliviral RNA-dependent RNA polymerase gene from lung tissue. This case provides CeMV sequence data available from the Gulf of Mexico and underscores the need for genomic sequencing across diverse host, temporospatial, and population (i.e., single animal vs. mass mortality events) scales to improve our understanding of these globally emerging pathogens.

A simultaneous diagnosis and genotyping method for global surveillance of cetacean morbillivirus.

Cetacean morbillivirus (CeMV) is considered one of the most important viral pathogens in cetaceans. CeMV outbreaks of lethal disease have repeatedly been observed in Europe, the Americas, and Australia, while large herds of gregarious species were found to be the likely reservoirs and sources of CeMV infection to susceptible species in the Atlantic and Pacific Oceans. Furthermore, three new strains were detected recently in Hawaii, Brazil and Australia. To clarify the real global distribution of CeMV and possible carriers, we showed a novel technique successfully diagnosing and distinguishing different virus strains (DMV, PWMV and novel CeMVs) using FFPE samples from 1996 to 2011. This efficient method that combines qRT-PCR and high resolution melting (HRM) could be applied to the future retrospective global studies for better understanding of different prevalence and outbreak conditions among ocean basins and the mechanism of variable host response to pathogens.

Fetal distress and in utero pneumonia in perinatal dolphins during the Northern Gulf of Mexico unusual mortality event.

An unusual mortality event (UME) involving primarily common bottlenose dolphins Tursiops truncatus of all size classes stranding along coastal Louisiana, Mississippi, and Alabama, USA, started in early 2010 and continued into 2014. During this northern Gulf of Mexico UME, a distinct cluster of perinatal dolphins (total body length <115 cm) stranded in Mississippi and Alabama during 2011. The proportion of annual dolphin strandings that were perinates between 2009 and 2013 were compared to baseline strandings (2000-2005). A case-reference study was conducted to compare demographics, histologic lesions, and Brucella sp. infection prevalence in 69 UME perinatal dolphins to findings from 26 reference perinates stranded in South Carolina and Florida outside of the UME area. Compared to reference perinates, UME perinates were more likely to have died in utero or very soon after birth (presence of atelectasis in 88 vs. 15%, p < 0.0001), have fetal distress (87 vs. 27%, p < 0.0001), and have pneumonia not associated with lungworm infection (65 vs. 19%, p = 0.0001). The percentage of perinates with Brucella sp. infections identified via lung PCR was higher among UME perinates stranding in Mississippi and Alabama compared to reference perinates (61 vs. 24%, p = 0.01), and multiple different Brucella omp genetic sequences were identified in UME perinates. These results support that from 2011 to 2013, during the northern Gulf of Mexico UME, bottlenose dolphins were particularly susceptible to late-term pregnancy failures and development of in utero infections including brucellosis.