First species record of Strigea falconis Szidat, 1928 (Trematoda, Strigeidae) from gyrfalcon Falco rusticolus in Iceland-pros and cons of a complex life cycle.

Strigea falconis is a common parasite of birds of prey and owls widely distributed in the Holarctic. We aimed to characterise S. falconis from Iceland via integrative taxonomic approach and to contribute to the understanding of its circulation in the Holarctic. We recovered adult S. falconis from two gyrfalcons (Falco rusticolus) collected in 2011 and 2012 in Iceland (Reykjanes Peninsula, Westfjords) and characterised them by morphological and molecular genetic (D2 of rDNA, cox1, ND1 of the mDNA) methods. We provide the first species record of S. falconis in Iceland which to the best of our knowledge is its northernmost distributional range. The presence of S. falconis in Iceland is surprising, as there are no suitable intermediate hosts allowing completion of its life cycle. Gyrfalcons are fully sedentary in Iceland; thus, the only plausible explanation is that they acquired their infection by preying upon migratory birds arriving from Europe. Our data indicate that the most likely candidates are Anseriformes and Charadriiformes. Also, we corroborate the wide geographical distribution of S. falconis, as we found a high degree of similarity between our haplotypes and sequences of mesocercariae from frogs in France and of a metacercaria from Turdus naumanni in Japan, and adults from Buteo buteo and Circus aeruginosus from the Czech Republic. The case of Strigea falconis shows the advantages of a complex life cycle and also depicts its pitfalls when a parasite is introduced to a new area with no suitable intermediate hosts. In Iceland, gyrfalcons are apparently dead-end hosts for S. falconis.

Wood mouse (Apodemus sylvaticus L.) as intermediate host for Mesocestoides canislagopodis (Rudolphi, 1810) (Krabbe 1865) in Iceland.

Mesocestoides canislagopodis is a common parasite of the arctic fox (Vulpes lagopus) in Iceland. In the past, household dogs (Canis familiaris) and cats (Felis catus) were also reported in Iceland to be infected. Recently, scolices of a non-maturing Mesocestoides sp. were detected in the intestines of the gyrfalcon (Falco rusticolus), and tetrathyridia were isolated in the body cavity of rock ptarmigan (Lagopus muta) and subsequently described. All stages were confirmed, using both morphological and molecular methods, to belong to the same species, M. canislagopodis. In the present study, post-mortem examination of wood mice (Apodemus sylvaticus), sampled in autumn 2014 on a farm in Northeast Iceland, revealed the presence of tetrathyridia in the peritoneal cavity and in the liver. Most tetrathyridia in the peritoneal cavity were free, but some were encapsulated in a thin connective tissue stroma and loosely attached to the inner organs. They appear as whitish, heart-shaped, flattened, unsegmented bodies with a slightly pointed posterior end. In the liver, tetrathyridia were seen as pale-tanned nodules embedded in the parenchyma. Comparative molecular analysis, both at the generic level (D1 domain LSU ribosomal DNA), and at the specific level (cytochrome c oxidase subunit I (cox1) and 12S mitochondrial DNA), revealed that the tetrathyridia belonged to M. canislagopodis. A. sylvaticus represents a new second intermediate host record in Iceland, and the first description of a rodent as intermediate host for this species, thus participating in the life cycle of the parasite.

Prey-mimetism in cercariae of Apatemon (Digenea, Strigeidae) in freshwater in northern latitudes.

Cercariae, the free-living larval stages of trematodes, have adopted an amazing variety of transmission strategies. One of them is prey-mimetism, i.e. cercariae mimicking prey to attract motile hosts to be eaten. In a period between 2002 and 2019, we examined small planorbid snails, Bathyomphalus contortus, Gyraulus parvus and Planorbis planorbis from lakes in Finland and Iceland and from the Curonian Lagoon in Lithuania. Cercariae with conspicuously enlarged tails and unusual swimming behaviour, likely mimicking invertebrate prey, were detected and studied by the use of morphological and molecular (cox1, ITS1-5.8S-ITS2 and 28S rDNA) methods. Cercariae of two species belonging to the genus Apatemon (Strigeidae) were recognised. We consider Apatemon sp. 5 ex P. planorbis from the Curonian Lagoon identical to Cercaria globocaudata U. Szidat, 1940. Cercariae ex G. parvus from Iceland and ex B. contortus from Finland were conspecific, and we named them Apatemon sp. 6; these cercariae could not be associated with any known species. For the first time, we verified that cercariae of the Bulbocauda group belong to the genus Apatemon. We provide a mini-review on records of furcocercariae of the family Strigeidae with enlarged tails reported in freshwaters of the northern hemisphere and reveal that it is not only Apatemon but also Australapatemon and most likely Strigea which belong to the Bulbocauda group, rendering it a purely ecological assemblage. Understanding which invertebrate swimming behaviour these cercariae are mimicking will enhance our knowledge of the processes behind trematode transmission and will help to assess evolutionary pathways of host-finding strategies in trematodes.

Diversity of echinostomes (Digenea: Echinostomatidae) in their snail hosts at high latitudes.

The biodiversity of freshwater ecosystems globally still leaves much to be discovered, not least in the trematode parasite fauna they support. Echinostome trematode parasites have complex, multiple-host life-cycles, often involving migratory bird definitive hosts, thus leading to widespread distributions. Here, we examined the echinostome diversity in freshwater ecosystems at high latitude locations in Iceland, Finland, Ireland and Alaska (USA). We report 14 echinostome species identified morphologically and molecularly from analyses of nad1 and 28S rDNA sequence data. We found echinostomes parasitising snails of 11 species from the families Lymnaeidae, Planorbidae, Physidae and Valvatidae. The number of echinostome species in different hosts did not vary greatly and ranged from one to three species. Of these 14 trematode species, we discovered four species (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, and Echinostomatidae gen. sp.) as novel in Europe; we provide descriptions for the newly recorded species and those not previously associated with DNA sequences. Two species from Iceland (Neopetasiger islandicus and Echinoparyphium sp. 2) were recorded in both Iceland and North America. All species found in Ireland are new records for this country. Via an integrative taxonomic approach taken, both morphological and molecular data are provided for comparison with future studies to elucidate many of the unknown parasite life cycles and transmission routes. Our reports of species distributions spanning Europe and North America highlight the need for parasite biodiversity assessments across large geographical areas.

TITLE: Diversité des Échinostomes (Digenea, Echinostomatidae) chez leurs hôtes mollusques aux latitudes élevées. ABSTRACT: La biodiversité des écosystèmes d'eau douce à l'échelle mondiale laisse encore beaucoup à découvrir, notamment dans la faune parasitaire des trématodes qu'ils abritent. Les parasites trématodes Échinostomes ont des cycles de vie complexes à hôtes multiples impliquant souvent des oiseaux migrateurs comme hôtes définitifs, conduisant ainsi à des distributions étendues. Ici, nous avons examiné la diversité des échinostomes dans les écosystèmes d'eau douce à des latitudes élevées en Islande, Finlande, Irlande et en Alaska (États-Unis). Nous rapportons de séquences de nad1 et d'ADNr 28S morphologiquement et moléculairement à partir d'analyses de données de séquence d'ADNr nad1 et 28S. Nous avons trouvé des échinostomes parasitant les mollusques de 11 espèces des familles Lymnaeidae, Planorbidae, Physidae et Valvatidae. Le nombre d'espèces d'échinostomes dans différents hôtes ne variait pas beaucoup et allait d'une à trois espèces. Sur ces 14 espèces de trématodes, nous avons découvert quatre espèces (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, Echinostomatidae gen. sp.) comme nouvelles pour l'Europe; nous fournissons des descriptions pour les espèces nouvellement signalées et celles qui n'étaient pas précédemment associées à des séquences d'ADN. Deux espèces d'Islande (Neopetasiger islandicus et Echinoparyphium sp. 2) ont été signalées en Islande et en Amérique du Nord. Toutes les espèces trouvées en Irlande sont de nouveaux signalements pour ce pays. Grâce à une approche taxonomique intégrative, des données morphologiques et moléculaires sont fournies à des fins de comparaison avec des études futures afin d'élucider les nombreux cycles de vie et voies de transmission des parasites, qui sont inconnus. Nos données sur la répartition des espèces en Europe et en Amérique du Nord soulignent la nécessité d'évaluer la biodiversité des parasites dans de vastes zones géographiques.

Transatlantic discovery of Notocotylus atlanticus (Digenea: Notocotylidae) based on life cycle data.

Digenean parasites feature a series of stages with a distinct appearance, reproduction mode, and lifestyle that together constitute their well-known, complex life cycle. Species descriptions of Digenea have always been based on one of these stages-the marita, or sexually reproducing adult in the final host. However, in some cases, data on the life cycle are essential for the differential diagnosis of closely related species. Here, we present the case of Notocotylus atlanticus, where different stages of its life cycle were discovered for the first time since the species description, and across the Atlantic. We used a material from a naturally infected intertidal marine snail, Ecrobia ventrosa, and several waterfowl species and also carried out infection experiments. For morphological studies, we employed light microscopy, SEM, and CLSM; molecular data obtained include sequences of ITS1 and 28S rRNA gene. We demonstrate that N. atlanticus adult worm morphology is barely sufficient to distinguish it from several other species. Cercariae morphology and identity of the first intermediate hosts provide crucial additional information. According to our preliminary phylogenetic reconstructions, two notocotylid lineages are associated with two major gastropod lineages-the Caenogastropoda and the Heterobranchia. The traditional character to identify notocotylid genera (structure of ventral organs) fails to explain the phylogeny and thus requires reassessment. Further reliable morphological, life cycle and molecular data on other species are likely to reveal more patterns in notocotylid systematics, host specificity, and evolution.

Ashworthius sidemi Schulz, 1933 and Haemonchus contortus (Rudolphi, 1803) in cervids in France: integrative approach for species identification.

Among gastro-intestinal nematodes, the blood-sucking worms belonging to the subfamily of Haemonchinae are considered to be of pathogenic and economic great importance, particularly in small ruminants. Haemonchus contortus, primary found in domestic ruminants and wild bovines (Mouflon, Chamois), is probably the most studied, but occurrence of Ashworthius sidemi has gradually increased over recent years, especially in Cervids and free roaming wild bovid as the European bison in eastern Europe, and some cases of co-infestation were recently observed on five Roe deer (Capreolus capreolus) and one Red deer (Cervus elaphus) in France. If the diagnosis is possible on the morphological features for adult worms for helminthologists, the identification on some stages (female, subadult, eggs and larvae) is difficult or impossible. Sequencing ND4 domain from the mitochondrial DNA of H. contortus and A. sidemi worms, we observed clearly two distinct clades, with an inter-specific divergence of 28.1%. Basing on this specific domain, a multiplex PCR-based method was developed: new primers were designed and used pooled in one mix PCR, producing amplicons of 454bp for H. contortus and 330bp for A. sidemi, allowing a trivial and an inexpensive taxonomic affiliation after migration. This multiplex PCR-based method was developed here to distinguish H. contortus and A. sidemi regardless their developmental stage, easy to use for highlighting co-infestation cases in both wild and domestic ruminants. It is a non-invasive approach appearing as a good diagnostic tool relevant to coprological cultures.

Occurrence of Mesocestoides canislagopodis (Rudolphi, 1810) (Krabbe, 1865) in mammals and birds in Iceland and its molecular discrimination within the Mesocestoides species complex.

The life cycle of Mesocestoides tapeworms (Cestoda: Cyclophyllidea: Mesocestoididae) requires three hosts. The first intermediate host is unknown but believed to be an arthropod. The second intermediate host is a vertebrate. The primary definitive host is a carnivore mammal, or a bird of prey, that eats the tetrathyridium-infected second intermediate host. One representative of the genus, Mesocestoides canislagopodis, has been reported from Iceland. It is common in the arctic fox (Vulpes lagopus) and has also been detected in domestic dogs (Canis familiaris) and cats (Felis domestica). Recently, scolices of a non-maturing Mesocestoides sp. have also been detected in gyrfalcon (Falco rusticolus) intestines, and tetrathyridia in the body cavity of rock ptarmigan (Lagopus muta). We examined the taxonomic relationship of Mesocestoides from arctic fox, gyrfalcon, and rock ptarmigan using molecular methods, both at the generic level (D1 domain LSU ribosomal DNA) and at the specific level (cytochrome c oxidase subunit I (COI) and 12S mitochondrial DNA). All stages belonged to Mesocestoides canislagopodis. Phylogenetic analysis of the combined 12S-COI at the specific level confirmed that M. canislagopodis forms a distinct clade, well separated from three other recognized representatives of the genus, M. litteratus, M. lineatus, and M. corti/vogae. This is the first molecular description of this species. The rock ptarmigan is a new second intermediate host record, and the gyrfalcon a new primary definitive host record. However, the adult stage seemed not to be able to mature in the gyrfalcon, and successful development is probably restricted to mammalian hosts.

Prevalence and intensity of Alaria alata (Goeze, 1792) in water frogs and brown frogs in natural conditions.

In the last 15 years, the mesocercariae of Alaria alata have frequently been reported in the wild boar during routine Trichinella inspections made compulsory for the trade of venison meat in Europe. If these studies have focused primarily on mesocercariae isolated from meat, few works have been done so far to understand the circulation of the parasite in natural conditions especially in the intermediate hosts. This study focuses on the second intermediate hosts of this parasite assessing the suitability of two amphibian groups-brown frogs and water frogs sensu lato-for mesocercarial infection on an area where A. alata has already been identified in water snails and wild boars. During this study, both groups showed to be suitable for mesocercarial infection, with high prevalence and parasite burdens. Prevalence was higher in the brown frog group (56.9 versus 11.54 % for water frogs) which would indicate that it is a preferential group for infection on the study area, though reasons for this remain to be investigated. No significant difference among prevalences was observed between tadpoles and frogs. This study, the first focusing on A. alata in these amphibians in Europe, provides further information on circulation of this parasite in natura.

Intermediate hosts of Protostrongylus pulmonalis (Frölich, 1802) and P. oryctolagi Babos, 1955 under natural conditions in France.

BACKGROUND: Protostrongylus oryctolagi and P. pulmonalis are causative agents of pulmonary protostrongyliasis in Lagomorphs in France. These nematodes need usually one intermediate host for its life cycle, a terrestrial snail. However, some studies, mainly in experimental conditions, have identified the species of snails acting as intermediate hosts. METHODS: In total, 3315 terrestrial snails and 307 slugs were collected in the field in South-Eastern France and analyzed to detect the presence of parasites. Identification of nematode parasites and snails were performed according to morphological and molecular approaches (D2 domain of the 28S rDNA for parasites; 18S and ITS-1 rDNA, COI and 16S mtDNA for snails). RESULTS: Eighteen snails were found positive for Protostrongylids larvae. Haplotypes of the larvae corresponding to sequences of P. oryctolagi and P. pulmonalis were detected. Morphological identification of molluscs based on shell characters revealed 4 different morphotypes, and molecular results confirm the membership of these gastropods to the Hygromiidae and revealed 4 different species: Candidula gigaxii, 2 species of Cernuella sp. and Xeropicta derbentina. All infested snails were collected in wine cultures. CONCLUSION: This study displays the first description of intermediate hosts of P. oryctolagi and the first report of X. derbentina as natural intermediate host of P. pulmonalis.

Development of 12 novel polymorphic microsatellite markers using a next generation sequencing approach for Spiculopteragia spiculoptera, a nematode parasite of deer.

Twelve novel polymorphic microsatellite markers were produced and characterized for Spiculopteragia spiculoptera (Nematoda, Trichostrongyloidae) a common parasite of abomasum of Roe and Red deer, using next generation sequencing approach, and two multiplexes PCR were developed with these markers. Polymorphism of each locus was tested in 40 individuals of this species from diverse wild populations of cervids, and was tested for crossed-amplification on four other species of nematodes, close to S. spiculoptera among the Trichostrongyloidea: 20 Spiculopteragia houdemeri, 34 Ostertagia leptospicularis, 16 Ashworthius sidemi, and 25 Trichostrongylus spp. Our new microsatellite markers seem to be specific to Spiculopteragia spiculoptera since no amplifications were obtained for the four other species. The number of alleles per locus ranged from 2 to 12, the average observed and expected heterozygosity per locus ranged from 0.025 to 0.641 and from 0.049 to 0.664, respectively. Four of the 12 microsatellite loci showed significant deviations from Hardy-Weinberg equilibrium (which two slightly significant). One locus pair showed significant linkage disequilibrium (Sspi4 vs. Sspi8). Neither evidence of scoring error due to stuttering nor evidence of large allele dropout was found at all of the 12 loci, but evidence of null alleles was indicated at three loci because of general excess of homozygotes for most allele size classes. These polymorphic loci will be useful markers to study population genetics structure of Spiculopteragia spiculoptera in order to understand transfer and to explain the relationships between deer populations.

Identification of Chabertiidae (Nematoda, Strongylida) by PCR-RFLP based method: a new diagnostic tool for cross transmission investigation between domestic and wild ruminants in France.

We describe a PCR-RFLP-based method that allows reliable identification of four species of nematode parasites presenting similar infective third-stage larvae (L3) with a flagelliform tail and more than 16 intestinal cells, commonly observed in gastrointestinal tract of ruminants in France. Molecular analysis of the second internal transcribed spacer (ITS2) of ribosomal DNA, considered as a specific marker for Strongylida, revealed four robust monophyletic clades corresponding to species Chabertia ovina, Oesophagostomum sikae, Oesophagostomum radiatum and Oesophagostomum venulosum. One restriction enzyme (DdeI) was used to digest this domain, and we observed four different and clear digestion patterns according to these species (adults or larvae). Hence, this new method is a good tool easy to use for veterinary laboratories to characterize the different species, and allows considering possible cross transmission between domestic and wild ruminants, especially cervids often incriminated as potential reservoir of parasites for cattle. Moreover, thanks to this new tool, necroscopic analyses could be substituted by coprological methods, a non-invasive approach.

Protostrongylus pulmonalis (Frölich, 1802) and P. oryctolagi Babos, 1955 (Nematoda: Protostrongylidae), parasites of the lungs of European hare (Lepus europaeus L.) in France: morphological and molecular approaches.

Pulmonary protostrongyliasis of hare is a parasitic disease caused by nematodes belonging to the genus Protostrongylus (Nematoda, Protostrongylidae). During survey of wildlife disease in the South-East of France, pathologic examination of lungs from European hares found dead or hunter-killed between 2009 and 2012 was performed. Adult male worms were morphologically characterized and the identification confirmed by molecular biology (D2 domain of the 28S and ITS2 of rDNA). Two different species were identified: the first one, Protostrongylus pulmonalis, is identical with the haplotype previously deposited in GenBank. Based on morphological criteria of copulatory bursa of adult male worms (especially length of spicules and gubernaculum structure), we identified a second species found in France as Protostrongylus oryctolagi. This is the first report of P. oryctolagi in France from European hare and rabbit. P. oryctolagi was isolated from 248 hares and 3 rabbits in the South of France. P. pulmonalis was isolated from four hares found dead in the Northern France and from one hare in the South, which was co-parasitized by P. oryctolagi and P. pulmonalis. It's the first coinfection observed with these two species from a lung of hare in France.

Trichobilharzia mergi sp. nov. (Trematoda: Digenea: Schistosomatidae), a visceral schistosome of Mergus serrator (L.) (Aves: Anatidae).

Parasitological investigations on red-breasted mergansers (Mergus serrator L.) in Iceland revealed digenean flukes of the family Schistosomatidae. Adult worms were detected in blood vessels of the large intestine and eggs were deposited in the mucosa and surrounded by granulomatous reactions. Traditional morphological methods showed that the flukes have very slender filiform bodies, males are equipped with a short gynaecophoric canal and both suckers and spatulate ends are present on each sex. Among characteristics of the flukes which render them morphologically distinct from other Trichobilharzia species are: i) males-well developed vesicula seminalis (v.s.) consisting of a short v.s. externa and a significantly longer (approx. 3 times) v.s. interna, unusually well developed genital papilla and localization of the first testis a relatively long distance posterior to the gynaecophoric canal; ii) eggs-small and elongated with slightly rounded poles and a short terminal spine. DNA taxonomic techniques confirmed that a new species had been identified, Trichobilharzia mergi sp. n. The sequence data were deposited in GenBank under the accession numbers JX456151 to JX456172. Comparison of the results with our previously published data on characterization of DNA of cercariae isolated from freshwater lymnaeid snails showed that larval development of T. mergi is associated with Radix balthica L. (=Radix peregra Müller, 1774;=Radix ovata Draparnaud, 1805).

Anserobilharzia gen. n. (Digenea, Schistosomatidae) and redescription of A. brantae (Farr & Blankemeyer, 1956) comb. n. (syn. Trichobilharzia brantae), a parasite of geese (Anseriformes).

A new genus, Anserobilharzia, is proposed to accommodate Anserobilharzia brantae n. comb. (syn. Trichobilharzia bran- tae Farr & Blankemeyer, 1956), a species of avian schistosome thus far found exclusively in anserini geese (Anser, Branta, Chen) from Europe and North America, and Gyraulus snails. Recent collections and subsequent molecular analyses showed that A. brantae was distinct from Allobilharzia and Trichobilharzia and grouped basal to Trichobilharzia. Using nuclear 28S, ITS and mitochondrial cox1 as genetic yardsticks, samples of A. brantae from North America and Europe were each other's closest relative and distinct from Allobilharzia and Trichobilharzia. Anserobilharzia brantae was also distinct when compared morphologically with other species of closely related avian schistosomes. The following descrip- tion is based on males, females, eggs, and cercariae. The new genus is characterized by a) ovoid egg (72-145µm x 44- 89 µm) with spine, b) male with > 500 testes and caecal reunion anteriad to seminal vesicle, c) cercariae with 5+1 flame cells, and d) intermediate hosts are planorbid snails. The only confirmed species of snail host is Gyraulus parvus in North America. Based on presented data, we propose a new genus and new combination for A. brantae justified by morpholog- ical, host use, and molecular characteristics.

Characterization of two cryptic species, Culicoides stigma and C.parroti (Diptera: Ceratopogonidae), based on barcode regions and morphology.

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are insect vectors of economically important veterinary diseases such as African horse sickness, bluetongue, and Schmallenberg virus. The identification of Culicoides based on morphological features can be difficult. Three species of biting midges, Culicoides nubeculosus, C. stigma, and C. parroti have emerged in the laboratory from mud collected around watering troughs on a farm in northern France. Emerging Culicoides were characterized morphologically and molecularly using molecular markers. The closely related species C. stigma and C.parroti showed highly divergent sequences for both mitochondrial (cytochrome B and cytochrome oxidase I) and ribosomal DNA first internal transcribed spacer. A RFLP based on a single restriction using the same enzyme (HaeIII) for both cytochrome C oxidase I and cytochrome B is proposed to identify these species.

Air sac fluke Circumvitellatrema momota in a captive blue-crowned motmot (Momotus momota) in France.

Postmortem examination of a 4-mo-old captive-born blue-crowned motmot (Momotus momota) at the Montpellier Zoo in France revealed the presence of air sac flukes. Circumvitellatrema momota (Digenea: Cyclocoelidae) was suspected and confirmed by molecular genetic analysis. Digenean metacercariae were extracted from an invasive species of terrestrial snail, the conical periwinkle, Subulina striatella. Molecular genetic analysis determined that these metacercariae were also C. momota, confirming that all the stages of this parasite's life cycle were present and that birds were likely becoming infected by eating these infected snails. It is likely that this trematode was imported into the greenhouse with a wild-caught motmot. The conical periwinkle snail appears to have been imported into the zoo with the plants in 2007 when the greenhouse was built. Treatments, which have been disappointing, are discussed, as well as preventive measures to avoid dissemination of the parasite into other bird collections in Europe.

Detection of Planorbis planorbis and Anisus vortex as first intermediate hosts of Alaria alata (Goeze, 1792) in natural conditions in France: molecular evidence.

Alaria alata (Goeze, 1792), a trematode that parasitizes canids, usually needs two intermediate hosts to complete its life cycle: an aquatic freshwater snail and an amphibian. Although many studies have been undertaken on the wild boar's role as paratenic host, owing to the potential threat to human health, few have sought to identify the snails that act as first intermediate hosts in natural conditions. Adopting a molecular approach, with specific markers for a portion of the second internal transcribed spacer (ITS-2), we detected haplotypes of A. alata furcocercariae in two snail species (Planorbis planorbis and Anisus vortex), identified by molecular analysis (ribosomal 18S, mitochondrial 16S and COI). This study provides the first description of snails naturally emitting A. alata furcocercaria in Western Europe.

Morphological features of the nasal blood fluke Trichobilharzia regenti (Schistosomatidae, Digenea) from naturally infected hosts.

The first author detected the nasal bird schistosome Trichobilharzia regenti in Iceland in Anas platyrhynchos in Landmannalaugar in autumn of 2003. Since then, measurements and morphological studies have been performed on fresh worms (fragments) obtained in the area from naturally infected ducks, A. platyrhynchos and Aythya marila. In the present study, we compare our findings to the original description of T. regenti by Horák et al. (Parasite 5:349-357, 1998) that relies upon worms obtained by experimental infections of A. platyrhynchos f. domestica and Cairina moschata f. domestica ducklings. Fragments obtained from naturally infected birds are markedly larger than those obtained in the experimental infection. Also, indistinct sex-related size difference was confirmed; males were more abundant in the material than females. Previously unknown morphological features detected in the present study include, e.g. subterminal spines on the oral sucker directed to the oral opening, spine pattern on the apical part of acetabulum and long tegumental spines (up to 16 µm) in the gonad and tail regions of both sexes. In males, we evaluated for the first time the morphology of the cirrus sac enclosing ejaculatory duct, prostata and the entire prostatic region, the course of vas deferens and the position of genital papilla. In females, the posterior part of the reproductive system was studied for the first time. The presence of the Laurer's canal was confirmed and its course from the oviduct to the surface, where spermatozoa were noticed to leave the canal, was described.

Final hosts and variability of Trichobilharzia regenti under natural conditions.

In Europe, despite of intensive work on avian schistosomes in the past, only one representative of nasal schistosomes has been detected so far, Trichobilharzia regenti, a species that remained undescribed to the scientific community until 1998. Since then, however, T. regenti has gained a considerable attention, not only due to the induction of serious lesions concomitant with the migration of the schistosomulae through the central nervous system of their natural hosts (birds) but also due to their implication in cercarial dermatitis and their neurotrophic behaviour in mammals (mice, experimental) where the parasite migrate to the CNS. From 2001 to 2010, by a parasitic control of various potential final hosts (aquatic birds) living in natural condition in France and in Iceland, we detected T. regenti in six species: Anas platyrhynchos, Cygnus olor, Aythya fuligula, Aythya ferina, Mergus merganser and Anser anser. Although morphological features, mainly of eggs, showed some variations with the original description of the parasite, molecular analysis confirmed their membership to the T. regenti species. Nevertheless, specific molecular and morphological variations were especially observed for nasal parasite isolated from Anas clypeata. For this species, we discuss the possibility for this nasal schistosome to belong to a nasal Trichobilharzia species already described in Africa or even an undescribed nasal species.

Trichobilharzia spp. in natural conditions in Annecy Lake, France.

Annecy Lake is a well-known focus of human cercarial dermatitis in France. Identification of the parasites, however, was not performed in the past. Previous studies suspected two species, Trichobilharzia franki and Trichobilharzia regenti, based on the presence of parasites in mallards and/or morphological identification of snails emitting ocellate furcocercariae. Following a standardized molecular approach, we studied snails and furcocercariae and compared their haplotypes with those deposited in GenBank. The selected markers were the second internal transcribed spacer ITS-2 for the snails and ITS-2 and D2 domain of the ribosomal DNA for the parasites. Our results confirm the presence of T. franki and T. regenti and two probable new species that could be potential agents of cercarial dermatitis. All the snails emitting the ocellate furcocercariae belong to the same species identified as Radix peregra (=Radix ovata = Radix balthica). Parasite-host relationships between species of the genus Trichobilharzia and snails of the genus Radix do not seem to be as specific as supposed previously.