Human and animal health is globally affected by a variety of parasitic helminths. The impact of co-infections and development of anthelmintic resistance requires improved diagnostic tools, especially for parasitic nematodes e.g., to identify resistant species or attribute pathological effects to individual species or particular species combinations. In horses, co-infection with cyathostomins is rather a rule than an exception with typically 5 to 15 species (out of more than 40 described) per individual host. In cyathostomins, reliable morphological species differentiation is currently limited to adults and requires highly specialized expertize while precise morphological identification of eggs and early stage larvae is impossible. The situation is further complicated by a questionable validity of some cyathostomins while others might actually represent cryptic species complexes. Several molecular methods using different target sequences were established to overcome these limitations. For adult worms, PCR followed by sequencing of mitochondrial genes or external or internal ribosomal RNA spacers is suitable to genetically confirm morphological identifications. The most commonly used method to differentiate eggs or larvae is the reverse-line-blot hybridization assay. However, both methods suffer from the fact that target sequences are not available for many species or even that GenBank® entries are unreliable regarding the cyathostomin species. Recent advances in proteomic tools for identification of metazoans including insects and nematodes of the genus Trichinella will be evaluated for suitability to diagnose cyathostomins. Future research should focus on the comparative analysis of morphological, molecular and proteomic data from the same cyathostomin specimen to optimize tools for species-specific identification.

Cyathostomins are important intestinal nematode parasites of equines and include 50 accepted species. Their taxonomy has been frequently revised and the presence of cryptic species suggested. Furthermore, usually molecular- and morphology-based phylogenetic analyses give divergent results. In this study, the nucleotide sequences of the nuclear second internal transcribed spacer (ITS-2) and the mitochondrial partial cytochrome c oxidase subunit I (COI) were determined for adults of six cyathostomin species (Coronocyclus coronatus, Coronocyclus labiatus, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus longibursatus, Cylicostephanus minutus) collected from different equine species within two geographic regions. Maximum likelihood trees were calculated for ITS-2, COI, and concatenated data. No obvious differentiation was observed between geographic regions or equine host species. As previously reported, Coronocyclus coronatus and Cylicostephanus calicatus revealed a close relationship. Cryptic species were detected in Cylicostephanus minutus and Cylicostephanus calicatus. Cylicocyclus nassatus and Coronocyclus labiatus showed diverse mitochondrial and nuclear haplotypes occurring in different combinations, while Cylicostephanus longibursatus was comparatively homogenous. In conclusion, a combined analysis of nuclear and mitochondrial haplotypes improved resolution of the phylogeny and should be applied to the remaining cyathostomin species and across additional equine host species and geographic regions.

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Rapid, cost-effective, efficient, and reliable helminth species identification is of considerable importance to understand host-parasite interactions, clinical disease, and drug resistance. Cyathostomins (Nematoda: Strongylidae) are considered to be the most important equine parasites, yet research on this group is hampered by the large number of 50 morphologically differentiated species, their occurrence in mixed infections with often more than 10 species and the difficulties associated with conventional identification methods. Here, MALDI-TOF MS, previously successfully applied to identify numerous organisms, is evaluated and compared with conventional and molecular genetic approaches. A simple and robust protocol for protein extraction and subsequent DNA isolation allowing molecular confirmation of proteomic findings is developed, showing that MALDI-TOF MS can discriminate adult stages of the two closely related cyathostomin species Cylicostephanus longibursatus and Cylicostephanus minutus. Intraspecific variability of proteomic profiles within morphospecies demonstrated an identification of morphospecies with an accuracy of close to 100%. In contrast, three genospecies within C. minutus and sex-specific profiles within both morphospecies could not be reliably discriminated using MALDI-TOF MS. In conclusion, MALDI-TOF MS complemented by the molecular protocol is a reliable and efficient approach for cyathostomin species identification.

In recent years, the protozoan parasite Toxoplasma gondii has increasingly been recognized in Arctic fauna, including beluga whales (Delphinapterus leucas) in the Eastern Beaufort Sea (EBS), Northwest Territories. We qualitatively assessed the risks of T. gondii to the health of EBS beluga because of their importance in livelihood of Arctic communities as well as their potential role as sentinels. This risk assessment used a standard framework including hazard identification, hazard characterization, exposure assessment, and risk characterization. We conclude that currently, the EBS beluga are at moderate risk of exposure to T. gondii, and low risk of developing disease associated with toxoplasmosis, based on the small amount of data available (only healthy, hunter-harvested animals have been examined). Although there was a high level of uncertainty due to limited published data and the challenges in determining prevalence and significance of disease in wild marine mammal populations, overall the EBS population was currently considered to be at a low risk for population level impacts of toxoplasmosis. Finally, we identify knowledge gaps that can guide future research, provide better evidence for future risk assessments, and Résumé : Au cours des dernières années, le parasite protozoaire Toxoplasma gondii a de plus en plus été reconnu dans la faune arctique, y compris chez les bélugas (Delphinapterus leucas) dans l'est de la mer de Beaufort (EMB), dans les Territoires du Nord-Ouest. Nous avons qualitativement évalué les risques de T. gondii pour la santé des bélugas dans l'EMB à cause de leur importance au niveau de la subsistance des communautés dans l'Arctique aussi bien que leur rôle potentiel comme sentinelles. Dans cette évaluation du risque, on a utilisé un cadre standard incluant l'identification des dangers, la caractérisation des dangers, l'évaluation de l'exposition et la caractérisation des risques. Nous concluons, fondé sur la faible quantité de données disponibles (seulement les animaux en bonne santé capturés par des chasseurs ont été examinés), qu'actuellement les bélugas de l'EMB sont à risque modéré d'exposition à T. gondii et à faible risque de développer une maladie associée à la toxoplasmose. Bien qu'il y ait un haut niveau d'incertitude en raison de la quantité limitée de données publiées et des défis quant à la détermination de la prévalence et de l'importance des maladies touchant les populations de mammifères marins sauvages, en général la population de l'EMB est considérée être à faible risque de subir des effets de toxoplasmose. Finalement, nous identifions les lacunes dans les connaissances qui peuvent guider les recherches futures, fournir de meilleures données pour l'évaluation des risques futurs et ultimement, mieux détecter et atténuer les risques changeants pour la santé des bélugas de l'Arctique, ainsi que les communautés qui dépendent de populations durables et saines pour la récolte. [Traduit par la Rédaction]Mots-clés : évaluation qualitative du risque, Toxoplasma gon...