Marine fish imported from Argentina as source of human diphyllobothriosis in Europe? Ecological evidence from dolphins.

Diphyllobothriosis caused by the Pacific broad tapeworm Adenocephalus pacificus (syn. Diphyllobothrium pacificum) is an emerging parasitic disease reported also from non-endemic areas, including Europe (Spain). The origin of these human cases is unknown but should be related to fresh marine fish imported from endemic areas. In this study, we molecularly confirmed common dolphins Delphinus delphis off Argentina as euparatenic transit hosts of A. pacificus. Preliminary analysis of their stomach content, together with data from previous studies from the Southwest Atlantic, showed that common dolphins feed almost exclusively on schooling Argentine hake Merluccius hubbsi and Argentine anchovy Engraulis anchoita. Therefore, we suggest that Argentine hake and Argentine anchovy may represent the intermediate hosts of A. pacificus in the Southwest Atlantic, but also in Europe to where M. hubbsi is imported on ice (unfrozen).

Detection and molecular characterization of Giardia and Cryptosporidium in common dolphins (Delphinus delphis) stranded along the Galician coast (Northwest Spain).

The ubiquitous protozoan parasites Giardia and Cryptosporidium have been detected from many species of captive and free-living wildlife, representing most mammalian orders. Twenty species of marine mammals have been reported to inhabit Galician waters and the region has one of the highest rates of stranding in Europe. Evidence from stranding, reported by-catches and sightings, suggests that the common dolphin (Delphinus delphis) is the most abundant cetacean on the Galician coast (Northwest Spain). The objective of this study was to detect and molecularly characterize isolates of Giardia and Cryptosporidium obtained from common dolphins stranded in this area. Between 2005 and 2012, sections of large intestine from 133 common dolphins stranded along the Galician coast were collected by the personnel of the Galician Stranding Network (Coordinadora para o Estudo dos Mamíferos Mariños, CEMMA). Using direct immunofluorescence antibody test (IFAT) and PCR amplification and sequencing of the SSU-rDNA, ß-giardin genes and the ITS1-5.8S-ITS2 region, Giardia and Cryptosporidium were detected in 8 (6.0%) and 12 samples (9.0%), respectively. In two samples, co-infection by both parasites was observed. The molecular characterization revealed the presence of Giardia duodenalis assemblages A (genotypes A1 and A2) and B and Cryptosporidium parvum in these samples. This constitutes the first study in which the presence of Giardia and Cryptosporidium has been investigated in common dolphins on the European Atlantic coast, and it is also the first report of C. parvum in this host. Our findings indicate that these animals could act as reservoir of these waterborne parasites or could be victims of the contamination originated by anthropogenic activities.

Intestinal helminth fauna of bottlenose dolphin Tursiops truncatus and common dolphin Delphinus delphis from the western Mediterranean.

We report on the intestinal helminth fauna of 15 bottlenose dolphins Tursiops truncatus and 6 short-beaked common dolphins Delphinus delphis from the western Mediterranean. Eight helminth species were found in bottlenose dolphin, i.e., the digeneans Synthesium tursionis, Brachycladium atlanticum, and Pholeter gastrophilus, the nematode Anisakis sp., and the cestodes Tetrabothrius forsteri, Diphyllobothrium sp., Strobilocephalus triangularis, and tetraphyllidean plerocercoids. Brachycladium atlanticum, S. triangularis , and tetraphyllidean plerocercoids are new host records. No T. forsteri had previously been reported in Mediterranean bottlenose dolphins. Three species of helminths were recorded in the common dolphin, i.e., the digenean Synthesium delamurei (which was a new host record), and the cestodes T. forsteri and tetraphyllidean plerocercoids. The intestinal helminth communities of bottlenose and common dolphins are depauperate, similar to that of other cetacean species, but those from bottlenose dolphins harbored a higher number of helminth species. This study supports the notion that oceanic cetaceans, such as common dolphins, have a comparatively poorer helminth fauna than that of neritic species, such as bottlenose dolphins, because the likelihood of parasite recruitment is decreased.

Eighteen-year study of South Australian dolphins shows variation in lung nematodes by season, year, age class, and location.

Between 1990 and 2007, carcasses of opportunistically collected short-beaked common dolphins (Delphinus delphis; n=238), Indo-Pacific bottlenose dolphins (Tursiops aduncus; n=167), and common bottlenose dolphins (Tursiops truncatus; n=15) were examined for parasites and life history data. Three species of lung nematodes (Halocercus lagenorhynchi, Stenurus ovatus, Pharurus alatus) were identified in surface nodules, subsurface lesions, or airways. Nematode burdens were light to heavy and, in many cases, would have compromised the dolphins' health. The number of dolphins infected was related to species, year, season, age class, and geographic region. Nematodes were found in all three species but were more prevalent in short-beaked common dolphins (mean annual prevalence=26%) than in bottlenose dolphins (12%). There was a significant increase in prevalence of nematodes in short-beaked common dolphins in 2005-06 (63%) compared to 1990-2004 (14%), with a peak in April-June. More young short-beaked common dolphins were infected than subadults and adults and, during the unusual infection event, there were more dependent calves (<130 cm) than juveniles. There were also more infections in dependent bottlenose dolphin (Tursiops spp.) calves but no increase in overall prevalence was detected during 2005-06. Because neonates of both short-beaked common dolphins and bottlenose dolphins were infected, mother-to-calf transmission is suspected for these species in South Australia. Numbers of infections in short-beaked common dolphins were higher in Gulf St Vincent than elsewhere in South Australia, particularly in 2005-06. The cause of the unusual infection event in short-beaked common dolphins is unknown. We discuss the influence of dolphin diet, life history, and external factors.

Occurrence of the ectoparasite Isocyamus deltobranchium (Amphipoda: Cyamidae) on cetaceans from Atlantic waters.

The cyamids collected from a True's beaked whale (Mesoplodon mirus), a common dolphin (Delphinus delphis), and a harbour porpoise (Phocoena phocoena) stranded in Galicia (NW Spain) were identified as Isocyamus deltobranchium, extending the range of this species to the Atlantic Ocean. The three cetacean species examined are new hosts for this parasite. The microscopic examination of female specimens reveals that certain important taxonomic characters can be present or absent depending on the maturation stage, an aspect which should be considered in future studies describing cyamid species.

Diseases, lesions and malformations in the long-beaked common dolphin Delphinus capensis from the Southeast Pacific.

Miscellaneous lesions of the head, skull, teeth, trunk, appendages, skin and genital tract were observed in 120 of 930 long-beaked common dolphins Delphinus capensis taken in fisheries off Peru between 1985 and 2000. Seven subsamples were defined according to the varying field sampling protocols. Forty-two dolphins showed at least 2 types of injuries or diseases affecting 1 or more organs. The majority (5 of 7) of traumas encountered were diagnosed as caused by violent, fisheries-related interactions, and the skin in 20.4 % of specimens (n = 54) showed healed scars from such interactions. Prevalences of malformations and traumas of crania (n = 103) were 2.9 and 1.9%, respectively. Lytic cranial lesions were present in 31.1% of dolphins (n = 103) and accounted for 84.2% of all bone injuries. Skull damage diagnostic for Crassicauda sp. infestation was encountered in 26.5% of dolphins (n = 98) and did not differ among sex and age classes. Crassicauda sp. and tooth infections were responsible for, respectively, 78.8 and 6.1% of the lytic lesions. Adult dolphins showed a high prevalence of worn and broken teeth (35%, n = 20) as well as damaged alveoli (20%, n = 70). Prevalence of 'paired teeth', a congenital condition, was 9.4% (n = 32). Lesions of the head, body and appendages were present in 10 dolphins and included traumas, deformations (e.g. scoliokyphosis and brachygnathia) and chronic mastitis. Ovarian cysts suggestive of follicular cysts were observed in 1 of 24 females. Chronic orchitis affected 1 of 78 males. Of 12 dolphins 2 had vesicular lesions of the penis. Prevalence of cutaneous lesions, abnormalities and scars ranged between 1.8% (n = 56) and 48.2% (n = 27).