Host Switching of Zoonotic Broad Fish Tapeworm (Dibothriocephalus latus) to Salmonids, Patagonia

Diphyllobothriosis is a reemerging zoonotic disease because of global trade and increased popularity of eating raw fish. We present molecular evidence of host switching of a human-infecting broad fish tapeworm, Dibothriocephalus latus, and use of salmonids as intermediate or paratenic hosts and thus a source of human infection in South AmericaFil: Kuchta, Roman. Academy of Sciences of the Czech Republic. Biology Centre. Institute of Parasitology; República ChecaFil: Radačovská, Alžbeta. Biology Centre of the Academy of Sciences of the Czech Republic; República ChecaFil: Bazsalovicsová, Eva. Slovak Academy of Sciences. Institute of Parasitology; EslovaquiaFil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Semenas, Liliana Graciela. Universidad Nacional del Comahue; ArgentinaFil: Arbetman, Marina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Scholz, Tomáš. Biology Centre of the Academy of Sciences of the Czech Republic; República Chec

Occurrence of Dibothriocephalus latus in European perch from Alpine lakes, an important focus of diphyllobothriosis in Europe

The broad fish tapeworm Dibothriocephalus latus (syn. Diphyllobothrium latum) is one of the most common causative agents of human diphyllobothriosis, a significant fish-borne parasitic zoonosis. In Europe, the occurrence of D. latus has been repeatedly reported in lakes of the Alps region, the Baltic region, Fennoscandia and Russia. Regular detection of D. latus plerocercoids in fish coming from different subalpine lakes linked with ongoing D. latus infection in humans indicates that Alpine region is a rather specific area from the medical, epidemiological and ecological point of view. Results from the examination of 688 European perch (Perca fluviatilis) from six subalpine lakes in Switzerland, France and northern Italy (Lakes Geneva, Neuchâtel, Biel, Como, Maggiore and Iseo) confirmed the ongoing occurrence of D. latus in the Alps region. The detected prevalence of D. latus in the studied Alpine lakes (2% in Lake Neuchâtel; 37.5% in Lake Biel; 6.4% in Lake Geneva; 22.8% in Lake Iseo [2018]; 12.8% in Lake Iseo [2017]; 15.2% in Lake Como; 16.7% in Lake Maggiore) was compared with previously published data. In addition, the importance of the Alpine lakes region and data on the epidemiology and ecology of D. latus related to subalpine lakes were discussed

Development of 14 microsatellite markers for zoonotic tapeworm dibothriocephalus dendriticus (Cestoda: Diphyllobothriidea)

Dibothriocephalus dendriticus is one of the causative agents of the fish-borne zoonosis diphyllobothriosis. Polymorphic microsatellite markers were originally developed for future genetic studies using microsatellite library screening and next-generation sequencing (NGS). Out of 128 microsatellite candidates selected after NGS analysis, 126 yielded PCR products of the expected size. A declared repetitive motif was confirmed in 92 loci by Sanger sequencing. The level of polymorphism was tested by fragment analysis. Statistical tests for observed and expected heterozygosities and deviations from Hardy–Weinberg equilibrium revealed 14 polymorphic microsatellite loci suitable for studies on the finer genetic structure of global populations of D. dendriticus

An examination of nervous system revealed unexpected immunoreactivity of both secretory apparatus and excretory canals in plerocercoids of two broad tapeworms (Cestoda: Diphyllobothriidea)

Dibothriocephalus ditremus and Dibothriocephalus latus are diphyllobothriidean tapeworms autochthonous to Europe. Their larval stages (plerocercoids) may seriously alter health of their intermediate fish hosts (D. ditremus) or cause intestinal diphyllobothriosis of the final human host (D. latus). Despite numerous data on the internal structure of broad tapeworms, many aspects of the morphology and physiology related to host–parasite co-existence remain unclear for these 2 species. The main objective of this work was to elucidate functional morphology of the frontal part (scolex) of plerocercoids, which is crucial for their establishment in fish tissues and for an early attachment in final hosts. The whole-mount specimens were labelled with different antibodies and examined by confocal microscope to capture their complex 3-dimensional microanatomy. Both species exhibited similar general pattern of immunofluorescent signal, although some differences were observed. In the nervous system, FMRF amide-like immunoreactivity (IR) occurred in the bi-lobed brain, 2 main nerve cords and surrounding nerve plexuses. Differences between the species were found in the structure of the brain commissures and the size of the sensilla. Synapsin IR examined in D. ditremus occurred mainly around FMRF amide-like IR brain lobes and main cords. The unexpected finding was an occurrence of FMRF amide-like IR in terminal reservoirs of secretory gland ducts and excretory canals, which has not been observed previously in any tapeworm species. This may indicate that secretory/excretory products, which play a key role in host–parasite relationships, are likely to contain FMRF amide-related peptide/s

Transmission patterns of Fasciola hepatica to ruminants in Sweden

Transmission patterns of Fasciola hepatica were investigated on beef cattle (n = 3) and sheep (n = 3) farms in Sweden between 2011 and 2012. The dynamics of fluke infection, particularly estimated time of infection, were screened each grazing season by ELISA detection of antibodies in lambs (n = 94) and first grazing season calves (n = 61). Colostral transfer of F. hepatica antibodies from seropositive ewes was detected in sheep up to 11 weeks of age. In sheep, the estimated time of infection differed significantly between herds and years. Typical 'winter infection' was observed on two sheep farms in 2012, but the most prevalent transmission pattern was found to be 'summer infection', characterised by infection of animals in late summer by F. hepatica originating from overwintered and/or spring-excreted eggs. In contrast, beef calves were infected mainly in September-October ('summer infection'). Furthermore, lymnaeid and succineid snails were collected on the pastures used by these animals both in spring and in the autumn each year. In total, 1726, 588, 138, 130, 93 and 42 specimens of Galba truncatula, Lymnaea palustris, Lymnaea glabra, Lymnaea fuscus, Radix peregra and Succinea putris, respectively, were collected and identified. These were subsequently examined for the presence of F. hepatica DNA by species-specific PCR and the findings compared against mean monthly rainfall and temperature data for each farm. The main intermediate host of the liver fluke was G. truncatula, with a prevalence range of F. hepatica infection from 0% to 82%. Only 1 out of 42 terrestrial S. putris tested positive for F. hepatica, casting doubt on the role of this species in transmission of F. hepatica in Sweden. In conclusion, two main peak periods of infection were observed: May-June (from overwintered infected snails = 'winter infection') and August-September (from metacercariae developed and produced by snails during summer = 'summer infection'). The occurrence and frequency of 'winter infection' were dependent on local environmental factors such as snail habitat availability or grazing behaviour of animals, rather than on climatic factors

Results on search for the broad fish tapeworm Dibothriocephalus latus (Linnaeus, 1758), (syn. Diphyllobothrium latum) (Cestoda: Diphyllobothriidea), in the Danube River

Diphyllobothriosis is a fish-borne parasitic zoonosis caused by so-called “broad tapeworms” or “fish tapeworms” of different genera of the order Diphyllobothriidea. Dibothriocephalus l atus (Linnaeus 1758), (syn. Diphyllobothrium latum), is a medically important type species of the genus, whose occurrence in various European regions is either regular, e.g. in the Alpine lakes region, or occasional and sporadic, e. g. in the Danube River region. For the latter, data on the detection of D. latus plerocercoids in the second intermediate fish host (European perch Perca fluviatilis), as well as in definitive hosts (human and dog), in which infection was directly linked to the consumption of infected fish from the Danube, were published more than 50 years ago. In order to assess the current situation, we aimed to find out whether D. latus is present in the natural environment of the Danube River. In total, 700 perch from five sampling sites in the Slovak part of the Danube River were examined. Plerocercoids were not detected in any fish examined, which leads to the conclusion that D. latus is currently not present in the studied aquatic environment

First record of Cathaemasia hians (Trematoda: Cathaemasiidae) in a new bird host, the Eastern Imperial Eagle (Aquila heliaca)

An injured young individual of the Eastern Imperial Eagle (Aquila heliaca; Accipitridae) from the Protected Bird Area „Medzibodrožie” in the south-eastern Slovakia was subjected to the complete clinical examination at the Clinic for Birds and Exotic Animals of the University of Veterinary Medicine and Pharmacy. Adult trematodes were isolated from the pharynx of the eagle after oesophagoscopy. The morphological and molecular identification of the flukes confirmed a trematode Cathaemasia hians (Cathaemasiidae), the obligate parasite of black storks (Ciconia nigra) and white storks (Ciconia ciconia). This finding represents the first documented case of C. hians in new bird host species and indicates broader spectrum of definitive hosts of the fluke

Genetic interrelationships of North American populations of giant liver fluke Fascioloides magna

Abstract Background Population structure and genetic interrelationships of giant liver fluke Fascioloides magna from all enzootic North American regions were revealed in close relation with geographical distribution of its obligate definitive cervid hosts for the first time. Methods Variable fragments of the mitochondrial cytochrome c oxidase subunit I (cox1; 384 bp) and nicotinamide dehydrogenase subunit I (nad1; 405 bp) were applied as a tool. The concatenated data set of both cox1 and nad1 sequences (789 bp) contained 222 sequences that resulted in 50 haplotypes. Genetic data were analysed using Bayesian Inference (BI), Maximum Likelihood (ML) and Analysis of Molecular Variance (AMOVA). Results Phylogenetic analysis revealed two major clades of F. magna, which separated the parasite into western and eastern populations. Western populations included samples from Rocky Mountain trench (Alberta) and northern Pacific coast (British Columbia and Oregon), whereas, the eastern populations were represented by individuals from the Great Lakes region (Minnesota), Gulf coast, lower Mississippi, and southern Atlantic seaboard region (Mississippi, Louisiana, South Carolina, Georgia, Florida) and northern Quebec and Labrador. Haplotype network and results of AMOVA analysis confirmed explicit genetic separation of western and eastern populations of the parasite that suggests long term historical isolation of F. magna populations. Conclusion The genetic makeup of the parasite’s populations correlates with data on historical distribution of its hosts. Based on the mitochondrial data there are no signs of host specificity of F. magna adults towards any definitive host species; the detected haplotypes of giant liver fluke are shared amongst several host species in adjacent populations