On the Helminth Fauna of the Muskrat (Ondatra zibethicus (Linnaeus, 1766)) in the Barnim District of Brandenburg State/Germany

The muskrat is a neozoon species that has occupied many countries of continental North Europe after its introduction from north America as fur animals. Due to its burrowing activity it damages river and canal banks and structures of flood control. For this reason, the eradication of this alien species is recommended. Muskrats are also of parasitological interest since they can act as suitable intermediate hosts for Echinococcus multilocularis. On the other hand, little is known on the other helminths that infect muskrats. A total of 130 muskrats of different age groups trapped in different habitats in the Barnim district of the Brandenburg state by a professional hunter were examined for parasites and seven trematodes (Echinostoma sp., Notocotylus noyeri, Plagiorchis elegans, Plagiorchis arvicolae, Psilosostoma simillimum, P. spiculigerum, Opisthorchis felineus and four larval cestode species (Hydatigera taeniaeformis, Taenia martis, Taenia polyacantha, Taenia crassiceps) were detected. Larval stages of E. multilocularis were not found. O. felineus was found for the first time in muskrats in Germany. All the named parasites were present in Europe prior to the introduction of muskrats. With a prevalence of 48.9%, Strobilocercus fasciolaris, the larval stage of the cat tapeworm, H. taeniaeformis, was the most frequent parasite found in adult muskrats.

Studies on gastrointestinal helminth of three Lacertid Lizard species, Podarcis muralis, Podarcis siculus and Ophisops elegans (Sauria: Lacertidae) from Bursa, North-Western Turkey

SummaryA total of 80 specimens of three species of lacertid Podarcis muralis (39), Podarcis siculus (18) and Ophisops elegans (23) from Bursa were examined for helminths. One species of Digenea, Plagiorchis elegans, 1 species of Cestoda, Mesocestoides sp. (tetrathyridium); and 3 species of Nematoda, Skrjabinodon medinae, Spauligodon saxicolae and Skrjabinelazia hoffmanni were found. The helminths reported in this study are generalist helminths that infect a number of lizards.

The First Record of Parthenitae and Cercariae of Plagiorchis Multiglandularis (Trematoda, Plagiorchiidae) in Lymnaea Stagnalis in Ukraine

Parthenitae and cercariae of Plagiorchis. multiglandularis Semenov, 1927 are recorded in Lymnaea stagnalis (Linnaeus, 1758) for the fi rst time in Ukraine; their morphological characteristics are specifi ed. Diagnostic characters of P. multiglandularis parthenitae and cercariae found in Ukrainian Polissia are compared with those from other regions. To confi rm the validity of the species, a comparison of the morphometric data of this trematode larvae with the cercariae of Plagiorchis elegans (Rudolphi, 1802) Braun, 1902, found in molluscs L. stagnalis, L. ralustris and L. corvuses, was performed. It was determined that P. multiglandularis cercariae diff er from those of P. elegans in size and position of the penetration glands.

Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans

ABSTRACTNeorickettsiaspp. are bacterial endosymbionts of parasitic flukes (Digenea) that also have the potential to infect and cause disease (e.g., Sennetsu fever) in the vertebrate hosts of the fluke. One of the largest gaps in our knowledge ofNeorickettsiabiology is the very limited information available regarding the localization of the bacterial endosymbiont within its digenean host. In this study, we used indirect immunofluorescence microscopy to visualizeNeorickettsiasp. within several life cycle stages of the digeneanPlagiorchis elegans. Individual sporocysts, cercariae, metacercariae, and adults ofP. elegansnaturally infected withNeorickettsiasp. were obtained from our laboratory-maintained life cycle, embedded, sectioned, and prepared for indirect immunofluorescence microscopy using anti-Neorickettsiaristiciihorse serum as the primary antibody.Neorickettsiasp. was found within the tegument of sporocysts, throughout cercarial embryos (germ balls) and fully formed cercariae (within the sporocysts), throughout metacercariae, and within the tegument, parenchyma, vitellaria, uteri, testes, cirrus sacs, and eggs of adults. Interestingly,Neorickettsiasp. was not found within the ovarian tissue. This suggests that vertical transmission ofNeorickettsiawithin adult digeneans occurs via the incorporation of infected vitelline cells into the egg rather than direct infection of the ooplasm of the oocyte, as has been described for other bacterial endosymbionts of invertebrates (e.g.,RickettsiaandWolbachia).

A molecular and ecological analysis of the trematodePlagiorchis elegansin the wood mouseApodemus sylvaticusfrom a periaquatic ecosystem in the UK

The prevalence of the digeneanPlagiorchissp. was investigated in a natural wood mouse population (Apodemus sylvaticus) in a periaquatic environment. Classical identification was complemented with the use of molecular differentiation to determine prevalence and verify species identity. Use of the complete ITS1-5.8S rDNA-ITS2 and partial 28S rDNA gene sequences have confirmed that the species reported at this location wasPlagiorchis elegansand notPlagiorchis murisas reported previously. This underlines the difficulties in identification of these morphologically similar parasites.Plagiorchis elegansis typically a gastrointestinal parasite of avian species but has also been reported from small mammal populations. Although the occurrence of this digenean inA. sylvaticusin the UK is rare, in the area immediately surrounding Malham Tarn, Yorkshire, it had a high prevalence (23%) and a mean worm burden of 26.6 ± 61.5. The distribution ofP. elegansfollowed a typically overdispersed pattern and both mouse age-group and sex were determined to be two main factors associated with prevalence. Male mice harboured the majority of worms, carrying 688 of 717 recovered during the study, and had a higher prevalence of 32.4% in comparison to only 8.7% in the small intestine of female mice. A higher prevalence of 43% was also observed in adult mice compared to 14% for young adults. No infection was observed in juvenile mice. These significant differences are likely to be due to differences in the foraging behaviour between the sexes and age cohorts of wood mice.

One snail – three Digenea species, different strategies in host-parasite interaction

The mostly lab-based studies on snail-trematode interactions should be complemented by research on naturally invaded hosts. In this mini-review, three different ways of snail exploitation by Digenea larvae are presented. Morphological, physiological and behavioral changes caused by three parasites in the same naturally infected host – Lymnaea stagnalis – differ in species-dependent fashion. The impact of a snail-trematode interaction depends on parasite virulence (i.e. parasite induced lost of fitness of the host). The pathogenicity varies with the survival strategy of the invader. Sporocyst-born Plagiorchis elegans, which uses the same Lymnaea stagnalis individual as a first but also as a second intermediate host, does not disturb host processes as strongly as redia-born Echinoparyphium aconiatum. The third parasite species – Diplostomum pseudospathaceum, also sporocyst-born – is more virulent than P. elegans, but it can modify and relax host exploitation to overwinter in the snail. The data presented demonstrate that successful use of first intermediate host can be arranged in different ways.