First record of Troglotrema acutum (Trematoda, Troglotrematidae) in European polecats Mustela putorius from Luxembourg.

We report the first record of the trematode Troglotrema acutum in skulls of European polecats (Mustela putorius) from Luxembourg. Thirty-one road-killed polecats from the northern and eastern parts of the country were examined. We found the trematode in three polecats from the administrative districts of Clervaux and Vianden in the northeast of the country. The parasites were detected in the frontal sinuses of one juvenile male as well as one adult of each sex. The animals were infected with six, nine and 13 adult trematodes, respectively, and we recovered 24 trematode eggs from one polecat. While the two adult hosts showed the lesions and deformations of the skull that are typical of T. acutum infections in polecats, the skull of the juvenile was not deformed. The prevalence of 9.7% reported here was lower than the values reported from Central European studies. Our findings indicate that the distribution range of T. acutum in western Central Europe extends to the Ardennes low mountain range.

Molecular identification of morphologically similar microcercous cercariae of two trematode families, Paragonimidae and Troglotrematidae, concurrently found in the same snail species of the subfamily Triculinae.

Microcercous cercariae possess a very short tail and are produced by digenean species of several families including medically important species, such as members of the genera Paragonimus Braun, 1899, Nanophyetus Chapin, 1927 and Troglotrema Odhner, 1914. During our survey of cercariae of Paragonimus spp. in Vietnam, we found microcercous cercariae from ten (0.29%) out of 3,400 snails of Triculinae gen. sp. 2. They were morphologically and molecularly analysed for species identification. The molecular analysis, based on ITS2 sequences, revealed two distinct species: four specimens were identical to Paragonimus proliferus Hsia et Chen, 1964 (Paragonimidae Dollfus, 1939), and the other six specimens were closest to members of the family Troglotrematidae Odhner, 1914 and were temporarily named Troglotrematidae gen. sp. Morphologically, cercariae of the two species found in this study are similar to each other in their gross characteristics but can be distinguished from one another by subtle morphological details. The cercaria of P. proliferus has an I-shaped excretory bladder and does not have mucous gland cells. In contrast, that of Troglotrematidae gen. sp. has a Y-shaped excretory bladder and mucous gland cells. Besides, the redia of P. proliferus is elongate with a short intestine and contains 5-6 cercariae whereas that of Troglotrematidae gen. sp. is more round with a longer intestine and harbours 3-4 cercariae. Our results have shown the importance of the shape of the excretory bladder and the presence/absence of mucous gland cells of the cercaria as well as the shape and size of the redia, and its intestinal length as valuable taxonomic characters of intramolluscan trematode larvae. In addition, the finding of similar microcercous cercariae of different species in the same snail species suggests that careful attention to morphological details is required in the differentiation of Paragonimus cercariae and those of closely related species.

Digeneans of northern fur seals Callorhinus ursinus (Pinnipedia: Otariidae) from five subpopulations on St. Paul Island, Alaska.

A parasitological survey of 651 northern fur seals Callorhinus ursinus L. from five subpopulations was conducted on St. Paul Island, Alaska, during July-August 2012-2014. Digenean trematodes were found in 210 of 651 fur seals with a total prevalence of 32.3%. Intensity of infection varied from 1 to 1540 parasites with mean intensity 18.4 ± 111.1 SD and median intensity of 2 specimens per host. Significant differences in prevalence and intensity of infection in northern fur seals between separate rookeries was not observed (Mann-Whitney test; p > 0.05). Four species of digeneans belonging to the families Heterophyidae (Apophallus zalophi Price, 1932, Phocitrema fusiforme Goto and Ozaki, 1930, and Galactosomum ubelakeri (Dailey, 1969)) and Troglotrematidae (Nanophyetus salmincola (Chapin, 1926)) were found. Nanophyetus salmincola is reported from C. ursinus for the first time. We obtained partial 28S rDNA sequences for all digenean species and conducted molecular phylogenetic analysis to demonstrate their phylogenetic relationships.

Genetic divergence of human pathogens Nanophyetus spp. (Trematoda: Troglotrematidae) on the opposite sides of the Pacific Rim.

Human and animal nanophyetiasis is caused by intestinal flukes belonging to the genus Nanophyetus distributed on both North American and Eurasian coasts of Northern Pacific. In spite of the wide geographical distribution and medical and veterinary importance of these flukes, the intra-generic taxonomy of Nanophyetus spp. remains unresolved. The two most widely distributed nominal species, Nanophyetus salmincola and Nanophyetus schikhobalowi, both parasitizing humans and carnivorous mammals, were described from North America and eastern Eurasia, respectively. However, due to their high morphological similarity their interrelationships remained unclear and taxonomic status unstable. In this study, we explored genetic diversity of Nanophyetus spp. from the Southern Russian Far East in comparison with that of samples from North America based on the sequence variation of the nuclear ribosomal gene family (18S, internal transcribed spacers, ITS1-5·8S-ITS2 and 28S). High levels of genetic divergence in each rDNA region (nucleotide substitutions, indels, alterations in the secondary structures of the ITS1 and ITS2 transcripts) as well as results of phylogenetic analysis provided strong support for the status of N. salmincola and N. schikhobalowi as independent species.

Life-history trade-offs in a generalist digenean from cetaceans: the role of host specificity and environmental factors.

BACKGROUND: Adults and larvae of generalist parasites are exposed to diverse hosts and local environmental conditions throughout their life cycles, thus local adaptation is expected to occur through phenotypic plasticity and/or natural selection. We investigated how the combined effect of cryptic host specificity and local selective pressures could shape reproductive traits of a putative generalist parasite in the oceanic realm. METHODS: The LSU rDNA, ITS2 and the mt-COI of individuals of the digenean Pholeter gastrophilus (Kossack, 1910) Odhner, 1914 (Heterophyidae Leiper, 1909) from oceanic striped dolphins, Stenella coeruleoalba Meyen, and coastal bottlenose dolphins, Tursiops truncatus Montagu, in the western Mediterranean were used to elucidate whether worms were conspecific. Infection parameters were compared between both dolphin species. General Linear Mixed Models were used to analyse the influence of host species on four reproductive traits of P. gastrophilus: body size, maturity stage (non-gravid/gravid), egg size, and number of eggs in utero. AIC values were used to rank competing models, and p-values to assess the effect of specific predictors. RESULTS: Evidence indicated that worms collected from both dolphin species were conspecific. All worms collected were gravid and infection parameters did not differ between dolphin species. However, body size and egg size of individuals of P. gastrophilus were significantly larger in striped dolphins. The number of eggs in utero did not significantly differ between dolphin species but, for a given body size, worms in bottlenose dolphins harboured more eggs. A trade-off between egg size and egg number was found in worms from both dolphin species, with a higher slope in striped dolphins. CONCLUSIONS: Apparently, striped dolphin is a more suitable host for P. gastrophilus, but reproductive investment seems to be adapted to the habitat where the life-cycle develops. Worms from striped dolphins likely face the problem of finding intermediate hosts in the oceanic realm and apparently invest into offspring size to enhance the early survival of larvae and the potential to multiply asexually within the first intermediate host. The small-sized worms from bottlenose dolphins would be adapted to reproduce early because of higher adult mortality, generating smaller and numerous eggs in a coastal habitat where chances of transmission are presumably higher.

Dissections of fresh skulls confirm low prevalence of Troglotrema acutum (Trematoda: Troglotrematidae) in German badgers (Meles meles).

We examined 131 European badgers Meles meles (Linnaeus, 1758) from 67 localities in central Germany for the presence of the cranial trematode Troglotrema acutum, as previous studies based on museum skulls might have underestimated the prevalence of the parasite in this host. We detected the flatworm in only three individuals that originated from the Rhoen Mountains (Thurigina and Bavaria). While the cranium of one host individual showed the lesions and the sponge-like widening of certain regions of the skullcap that are typical of a T. acutum infection, the skulls of the two remaining badgers did not show any deformations. The three badgers were infected by eight, 20, and 49 T. acutum individuals, respectively. Eggs of the trematode parasite were detected in the paranasal sinuses of two badgers. While badgers infected with T. acutum may not show any surface bone lesions, the results of the present study do not contradict the conclusion that the badger is only an accidental host of T. acutum.

First report of Troglotrema acutum (Digenea, Troglotrematidae) in the Eurasian badger Meles meles in the Iberian Peninsula and presumptive lesions caused in the host.

A total of 109 badger Meles meles skulls from Catalonia (north-eastern Iberian Peninsula) were studied for helminths. The tremadode Troglotrema acutum is reported here for the first time in the Eurasian badger in the Iberian Peninsula and southern Europe. Three methodologies were used to detect this trematode: an examination for surface lesions, axial computed tomography and fresh skull dissection. The damage caused in the affected skulls is described, along with details regarding the use of computed tomography to detect hyperostosis, leakage in the sinus structure and bone surface erosion in the affected skulls.

Identification of African Paragonimidae by multivariate analysis of the eggs.

A study of metacercariae and adult Paragonimidae revealed the existence in West-Africa of four species, of which two are largely recorded in literature (Paragonimus africanus and Paragonimus uterobilateralis), one was suspected (Paragonimnus westermani-like) and one remained unrecorded in Africa (Euparagonimus sp). Among the two last ones, P. westermani-like was probably confused with P. africanus, and Euparagonimus sp. with P. uterobilateralis. P. westermani-like adult worms differed from P. africanus by the morphology of ovary, testes and the size of the metraterm eggs. Euparagonimus could be identified by a short excretory bladder in metacercariae. The discriminant functions established on eggs measurements (average, maximum and minimum length, average, maximum and minimum width) were able to separate the isolates into four groups. The largest eggs (97 x 59 microm) belonged to P. westermani-like, the medium sized eggs were ascribed to P. africanus (91 x 49 microm) and to Euparagonimus sp. (84 x 50 microm), and the smaller eggs (69 x 42 microm) were identified as P. uterobilateralis. Three Paragonimidae were identified in Cameroon: P. westermani-like, P. africanus and Euparagonimus sp. Additionally, P. uterobilateralis, P. westermani-like, and Euparagonimus sp. were found in the Congo, Gabon, and the Ivory Coast, respectively.