Occlusive mycotic tracheobronchitis and systemic Alphaherpesvirus coinfection in a free-living striped dolphin Stenella coeruleoalba in Italy.

A juvenile female striped dolphin Stenella coeruleoalba live stranded on 4 March 2016 at Alassio, western Ligurian Sea coast, Italy. The dolphin died shortly after stranding, and a complete postmortem examination was performed. Necropsy revealed severe tracheal occlusion and unilateral bronchial stenosis with luminal accumulation of abundant green-yellow mucous-gelatinous material. Histological features suggestive of tracheobronchial aspergillosis were observed. Cultures of lung tissue and tracheo-bronchial exudate isolated Aspergillus fumigatus, identified by a Microseq D2 LSUrDNA fungal sequencing kit. A pan-Herpesvirus nested-PCR assay on frozen samples obtained from multiple organs was positive. Phylogenetic analysis on the partial DNA polymerase gene revealed that the striped dolphin isolate was closely related to known cetacean Alphaherpesvirus sequences from the same host species. Attempted virus isolation was unsuccessful. The tissue levels of different persistent organic pollutants and the toxicological stress, evaluated using a theoretical model, showed a severely impaired immune response. This study reports the first case of occlusive mycotic tracheobronchitis in a free-living cetacean and the first molecular identification of an Alphaherpesvirus in a free-ranging striped dolphin stranded on the coast of Italy.

Occurrence of Brucella ceti in striped dolphins from Italian Seas.

Brucella ceti infections have been increasingly reported in cetaceans, although a very limited characterization of Mediterranean Brucella spp. isolates has been previously reported and relatively few data exist about brucellosis among cetaceans in Italy. To address this gap, we studied 8 cases of B. ceti infection in striped dolphins (Stenella coeruleoalba) stranded along the Italian coastline from 2012 to 2018, investigated thanks to the Italian surveillance activity on stranded cetaceans. We focused on cases of stranding in eastern and western Italian seas, occurred along the Apulia (N = 6), Liguria (N = 1) and Calabria (N = 1) coastlines, through the analysis of gross and microscopic findings, the results of microbiological, biomolecular and serological investigations, as well as the detection of other relevant pathogens. The comparative genomic analysis used whole genome sequences of B. ceti from Italy paired with the publicly available complete genomes. Pathological changes consistent with B. ceti infection were detected in the central nervous system of 7 animals, showing non-suppurative meningoencephalitis. In 4 cases severe coinfections were detected, mostly involving Dolphin Morbillivirus (DMV). The severity of B. ceti-associated lesions supports the role of this microbial agent as a primary neurotropic pathogen for striped dolphins. We classified the 8 isolates into the common sequence type 26 (ST-26). Whole genome SNP analysis showed that the strains from Italy clustered into two genetically distinct clades. The first clade comprised exclusively the isolates from Ionian and Adriatic Seas, while the second one included the strain from the Ligurian Sea and those from the Catalonian coast. Plotting these clades onto the geographic map suggests a link between their phylogeny and topographical distribution. These results represent the first extensive characterization of B. ceti isolated from Italian waters reported to date and show the usefulness of WGS for understanding of the evolution of this emerging pathogen.

First report of Salmonella 1,4,[5],12:i:- in free-ranging striped dolphins (Stenella coeruleoalba), Italy.

Between 2015 and the beginning of 2018 (January-March), 30 cetaceans were found stranded along the Ligurian Sea coast of Italy. Necropsies were performed in 22 cases and infectious diseases resulted the most common cause of death. Three striped dolphins, showed a severe coinfection involving the monophasic variant of Salmonella Typhimurium (Salmonella 1,4,[5],12:i:-). The isolates were characterized based on antimicrobial resistance, Multiple-Locus Variable-number tandem-repeat Analysis (MLVA) and whole-genome sequencing (WGS). All isolates demonstrated the same multidrug resistant genotype (ASSuT isolates), showed three different MLVA profiles, two of which closely related, and were identified as Sequence Type 34. Moreover, Single nucleotide polymorphisms (SNP) analysis confirmed strong correlations between two out of the three isolates. To our knowledge, S. 1,4,[5],12:i:-, one of the most common serovars in cases of human infection and food sources worldwide, has not previously been described in marine mammals, and reports of Salmonella-associated disease in free-ranging cetaceans are rare. These results highlight the role of cetaceans as sentinel species for zoonotic and terrestrial pathogens in the marine environment, suggest a potential risk for cetaceans and public health along the North Western Italian coastline and indicate cetaceans as a novel potential reservoir for one of the most widespread Salmonella serovars.

RETROSPECTIVE SURVEY FOR PATHOGENS IN STRANDED MARINE MAMMALS IN NORTHEASTERN BRAZIL: BRUCELLA SPP. INFECTION IN A CLYMENE DOLPHIN ( STENELLA CLYMENE).

: We surveyed 13 carcasses of marine mammals (12 Trichechus manatus and one Stenella clymene) that had stranded in northeastern Brazil during 1990-2013 for infectious diseases by screening tissues from the collection of the Brazilian National Center of Research and Conservation of Aquatic Mammal, Chico Mendes Institute for Biodiversity Conservation. Brucella spp. and Mycobacterium spp. were investigated by culturing and PCR of tissue samples, whereas Sarcocystidae parasites, Leptospira spp., and Morbillivirus were surveyed for using specific PCR assays. Brucella spp. and Mycobacterium spp. were not isolated through microbiologic culturing, and all animals were negative for detection of Sarcocystidae parasites, Leptospira spp., Mycobacterium spp., and Morbillivirus by PCR assays. All manatees were negative for Brucella spp. infection, but Brucella ceti was detected in the brain tissue of an S. clymene calf by using a PCR assay.

The microbiome of a striped dolphin (Stenella coeruleoalba) stranded in Portugal.

Infectious diseases with epizootic consequences have not been fully studied in marine mammals. Presently, the unprecedented depth of sequencing, made available by high-throughput approaches, allows detailed comparisons of the microbiome in health and disease. This is the first report of the striped dolphin microbiome in different body sites. Samples from one striped female edematous dolphin were acquired from a variety of body niches, including the blowhole, oral cavity, oral mucosa, tongue, stomach, intestines and genital mucosa. Detailed 16S rRNA analysis of over half a million sequences identified 235 OTUs. Beta diversity analyses indicated that microbial communities vary in structure and cluster by sample origin. Pathogenic, Gram-negative, facultative and obligate anaerobic taxa were significantly detected, including Cetobacterium, Fusobacterium and Ureaplasma. Phocoenobacter and Arcobacter dominated the oral-type samples, while Cardiobacteriaceae and Vibrio were associated with the blowhole and Photobacterium were abundant in the gut. We report for the first time the association of Epulopiscium with a marine mammal gut. The striped dolphin microbiota shows variation in structure and diversity according to the organ type. The high dominance of Gram-negative anaerobic pathogens evidences a cetacean microbiome affected by human-related bacteria.

Isolation of Clostridium tertium from a striped dolphin (Stenella coeruleoalba) in the Adriatic Sea.

Bacteriologic examination of an abscess found between blubber and musculature of a striped dolphin (Stenella coeruleoalba) found dead on 30 March 2002 in the Adriatic Sea, Croatia, was performed and an aerotolerant, nontoxogenic Clostridium tertium was isolated in pure culture. National Collections of Industrial Food and Marine Bacteria (NCIMB Ltd., Aberdeen, Scotland, UK) confirmed the results. Sequencing results showed it to be C. tertium with 100% similarity. The strain was named Clostridium tertium strain Zagreb, acceded to the culture collection and assigned the accession number NCIMB 13970. This is the first record of C. tertium in marine mammals.

Brucella ceti from two striped dolphins stranded on the Apulia coastline, Italy.

Since 1994, when Brucella ceti was first isolated from an aborted dolphin fetus, several cases have been reported worldwide. The first case of B. ceti in the Mediterranean (and in Italy), however, was recorded only in 2012, off the coast of Tuscany. Extensive studies, using serological and microbiological methods, have documented this bacterium in dolphins and demonstrated its zoonotic potential. We describe the typing of two B. ceti strains isolated from striped dolphins (Stenella coeruleoalba) stranded on the southern Apulia coastline. B. ceti isolates were conventionally typed, and then genotyped by both the multilocus sequence typing (MLST) and the multilocus variable number of tandem repeats typing (MLVA) methodologies to infer phylogeny and potential epidemiological links between the two cases. The two isolates were identified through MLST analysis as belonging to the common sequence type 26 (ST26), while MLVA analysis, having established that the two isolates have identical profiles, assigned them to a novel genotype within cluster A - a unique representative of a new Mediterranean subcluster. The results thus revealed a link between the two cases studied, demonstrating the usefulness of MLST and MLVA for the epidemiological investigation of brucellae among marine mammals.

Detection of Helicobacter in the digestive tract of an Atlantic spotted dolphin (Stenella frontalis).

Helicobacter spp. occur in the digestive system of a broad range of animal taxa, including marine mammals. Only one formally recognized species, Helicobacter cetorum, has been described in marine mammals. Helicobacter has not been reported in the Atlantic spotted dolphin (Stenella frontalis). The purpose of our study was to examine the digestive tract of a stranded spotted dolphin for Helicobacter. Tissue and content samples were collected at necropsy and examined by histopathology and molecular analyses using Helicobacter genus-specific 16S rDNA polymerase chain reaction (PCR) and DNA sequencing. Helicobacter was detected in all stomach divisions and the duodenal ampulla. A sequence type of the 16S rRNA gene shared a 98-99% identity to sequences from H. cetorum. This study reports for the first time Helicobacter in S. frontalis.