International journal for parasitology最新文献

Fasciola hepatica (the liver fluke) is an important parasite of cattle and sheep globally. Current diagnostic tests are laboratory based, which involve costs for sample collection and time taken for results to be returned. This can discourage farmers from engaging with the industry message to test before treating. Treatment in the absence of a diagnosis can contribute to the development of resistance to anthelmintics. We have developed a lateral flow test (LFT) to detect antibodies to fluke in whole blood, which can be used on-farm to detect exposure in cattle and sheep within 10 min. LFT performance was evaluated though on-farm trials sampling 10 sheep on 24 farms, and where possible, up to 10 cattle. Results were compared to those obtained with an in-house antibody detection ELISA. Linear regression analysis showed a positive correlation between LFT and ELISA results. Bayesian analysis assuming no gold standard indicated that the LFT had a sensitivity (Se) of 77 % (95 % Credible Interval [CI] 61-91 %) and specificity (Sp) of 80 % (CI 70-89 %) in cattle and 67 % Se (CI 47-94 %) and 71 % Sp (CI 62-82 %) for sheep. Sub-setting for first season lambs gave 96 % Se (CI 85-100 %) and 74 % Sp (CI 65-84 %). A group interview with the farmers who participated in on-farm trials indicated they found the LFT easy to use and thought it would be a useful tool to guide treatment decisions. The LFT will enable farmers to better engage with fluke management on their farms and encourage appropriate use of anthelmintics.

Schistosomiasis is a neglected tropical disease affecting over 250 million people worldwide. Schistosoma parasites can survive in the human host for years due to their capability to evade and modulate host immune responses. Glycans and glycoproteins produced by schistosomes are thought to play an important role in shaping parasite-host interactions. In addition, N-linked glycans are vital post-translational protein modifications involved in fundamental cellular and developmental processes like protein folding and cell-cell interactions. In this study, we generated live Schistosoma mansoni adult worms with altered N-glycosylation using the α-mannosidase inhibitors kifunensine and swainsonine, compounds which restrict complex N-glycan processing thereby preventing complex N-glycan formation. We show that ex vivo cultured adult schistosomes display a stable N-glycosylation profile during two weeks of culture characterised by roughly one-third mannose and two-third complex glycans. Inhibition of α-mannosidases during culture resulted in a modified N-glycan profile over time: kifunensine-treated parasites were found to contain 76% mannose N-glycans, while swainsonine-treated parasites showed a strongly increased abundance of hybrid glycans and (fucosylated) mannose glycans. These observations are in line with the expected effect of the inhibitors on endoplasmic reticulum and Golgi α-mannosidases, respectively. Additionally, we examined the N-glycan composition of the worm tegument, a major parasitic structure found at the parasite-host interface. The tegument contained mainly complex N-glycans, often carrying the GalNAcβ1-4GlcNAc (LacdiNAc, LDN) motif, different from the rest of the schistosome body. Again, α-mannosidase inhibition changed the N-glycosylation profile of the tegument, similarly as observed for whole worms. No negative effects of any of the treatments on parasite motility or morphology were observed, indicating that the basic biology of the worms in culture was not affected by these N-glycosylation changes. Our results demonstrate the feasibility of creating a live glyco-remodelled parasite, setting the scene for studying functional parasite glycobiology and glycan-mediated effects in host-parasite interaction.

Cercariae of the zygocercous morphotype represent a fascinating and unique morphological and ecological adaptation among trematodes (Digenea). They are characterised by an unusual behaviour in which individuals join their tails to form rosette-like clusters consisting of several to hundreds of cercariae that actively move in the water by wagging their tails, resulting in a rolling motion. This aggregation behaviour is a textbook example of prey mimetism, a strategy in which a parasite resembles the prey of a predator (i.e., the next host in the life cycle) in its appearance and movements. In this article, we review all known reports of zygocercous cercariae, whose identity is largely unknown. A total of 16 putative species forming groups of 'rat-king' type cercariae (i.e., zygocercous) have been documented in freshwater and marine snails in 12 countries worldwide. Zygocercous cercariae occur in several unrelated groups of trematodes and have evolved independently several times, apparently as an effective ecological adaptation to increase the success of transmission of the cercariae to the next host, usually a fish. In addition, we report newly discovered zygocercous cercariae found in the non-pulmonate snail Microcolpia daudebartii acicularis (Férussac) (Caenogastropoda: Melanopsidae) from the Danube River in Slovakia. This is the first record of this type of cercaria in Europe in almost 150 years. Molecular data suggest that these cercariae belong to the recently resurrected genus Mesorchis Dietz, 1909 (Echinochasmidae), which includes species with 20 or 22 collar spines. Five taxa previously assigned to the genus Echinochasmus Dietz, 1909 (whose species generally have 24 collar spines) and for which molecular data are available are hereby transferred to Mesorchis as new combinations.

In this study, DNA was sequenced from adults of Patagifer Dietz, 1909 and Nephrostomum Dietz, 1909 (Digenea: Echinostomatidae) collected from avian definitive hosts in Nearctic, Neotropic, Palearctic and Afrotropic regions. Phylogenetic analyses of entire mitochondrial genomes, nuclear rDNA operons, and partial 28S, ITS2, cox1, and nad1 all indicate that Nephrostomum is synonymous with Patagifer, which is given priority, and that head-collar characters formerly used to separate these genera represent traits that vary among closely related congeneric species. Low interspecific divergence in partial 28S (0-0.41 %) in Patagifer has contributed to misidentifications, while mitochondrial markers provided greater resolution and revealed greater species diversity. Six species were included in the present study: P. ramosum, P. bilobus, P. vioscai, P. limai, an unidentified species known only from cercariae, and a new species with distinctive head collar morphology, from Theristicus caerulescens in Argentina. In both P. ramosum and P. bilobus, mitochondrial markers show intercontinental distributions that can be plausibly linked to historical transatlantic expansions of their Old-World avian hosts.

Some species of Anisakidae are known to cause human anisakidosis due to ingestion of seafood containing larvae L3. Although cartilaginous fishes are infrequently reported as hosts for anisakids, they could play a role in their transmission to definitive hosts. The occurrence and level of infestation by anisakids on 18 species of skates were analysed, based on a sample of 676 specimens. A total of 1692 worms were recorded; the morphologic and genetic analysis of mDNA cox2 gene, confirmed the presence of Anisakis pegreffii, A. berlandi and Phocanema cattani, whose presence and burdens varied among the species of skates examined. The models generated from prevalence and mean abundance data showed that both bathymetric distribution and length of skates influence the anisakid load in the host species studied. Phocanema cattani prevailed in coastal skates, whereas Anisakis spp. were more common at greater depths. Indeed, the molecular analysis showed that A. pegreffii was most frequent in skates species inhabiting coastal to middle shelf waters, while A. berlandi was relatively more common in skate species living in deeper waters. The knowledge of the epidemiology of anisakids in the Southwestern Atlantic is still incipient, particularly those studies employing molecular approaches. Despite this study being geographically limited and restricted to a closely related group of hosts, the observed patterns would be extensive to other latitudes and species. This would contribute to a more comprehensive understanding of the ecology of an emerging zoonoses, which have implications for human health and international trade; even more under a global warming scenario.