International journal for parasitology最新文献

{"title":"Comparative genomics analysis reveals sequence characteristics potentially related to host preference in Cryptosporidium xiaoi","authors":"Jiayu Li ,&nbsp;Yingying Fan ,&nbsp;Na Li,&nbsp;Yaqiong Guo,&nbsp;Weijian Wang,&nbsp;Kangli Feng,&nbsp;Wei He,&nbsp;Falei Li,&nbsp;Jianbo Huang,&nbsp;Yanhua Xu,&nbsp;Lihua Xiao,&nbsp;Yaoyu Feng","doi":"10.1016/j.ijpara.2024.03.004","DOIUrl":"10.1016/j.ijpara.2024.03.004","url":null,"abstract":"<div><p><em>Cryptosporidium</em> spp. are important diarrhea-associated pathogens in humans and livestock. Among the known species, <em>Cryptosporidium xiaoi</em>, which causes cryptosporidiosis in sheep and goats, was previously recognized as a genotype of the bovine-specific <em>Cryptosporidium bovis</em> based on their high sequence identity in the ssrRNA gene. However, the lack of genomic data has limited characterization of the genetic differences between the two closely related species. In this study, we sequenced the genomes of two <em>C. xiaoi</em> isolates and performed comparative genomic analysis to identify the sequence uniqueness of this ovine-adapted species compared with other <em>Cryptosporidium</em> spp. Our results showed that <em>C. xiaoi</em> is genetically related to <em>C. bovis</em> as shown by their 95.8% genomic identity and similar gene content. Consistent with this, both <em>C. xiaoi</em> and <em>C. bovis</em> appear to have fewer genes encoding mitochondrial metabolic enzymes and invasion-related protein families. However, they appear to possess several species-specific genes. Further analysis indicates that the sequence differences between these two <em>Cryptosporidium</em> spp. are mainly in 24 highly polymorphic genes, half of which are located in the subtelomeric regions. Some of these subtelomeric genes encode secretory proteins that have undergone positive selection. In addition, the genomes of two <em>C. xiaoi</em> isolates, identified as subtypes XXIIIf and XXIIIh, share 99.9% nucleotide sequence identity, with six highly divergent genes encoding putative secretory proteins. Therefore, these species-specific genes and sequence polymorphism in subtelomeric genes probably contribute to the different host preference of <em>C. xiaoi</em> and <em>C. bovis</em>.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 7","pages":"Pages 379-390"},"PeriodicalIF":4.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140140223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The unusual kinetics of lactate dehydrogenase of Schistosoma mansoni and their role in the rapid metabolic switch after penetration of the mammalian host","authors":"Michiel L. Bexkens ,&nbsp;Olivier M.F. Martin ,&nbsp;Jos M. van den Heuvel ,&nbsp;Marion G.J. Schmitz ,&nbsp;Bas Teusink ,&nbsp;Barbara M. Bakker ,&nbsp;Jaap J. van Hellemond ,&nbsp;Jurgen R. Haanstra ,&nbsp;Malcolm D. Walkinshaw ,&nbsp;Aloysius G.M. Tielens","doi":"10.1016/j.ijpara.2024.03.005","DOIUrl":"10.1016/j.ijpara.2024.03.005","url":null,"abstract":"<div><p>Lactate dehydrogenase (LDH) from <em>Schistosoma mansoni</em> has peculiar properties for a eukaryotic LDH<em>.</em> Schistosomal LDH (SmLDH) isolated from schistosomes, and the recombinantly expressed protein, are strongly inhibited by ATP, which is neutralized by fructose-1,6-bisphosphate (FBP). In the conserved FBP/anion binding site we identified two residues in SmLDH (Val187 and Tyr190) that differ from the conserved residues in LDHs of other eukaryotes, but are identical to conserved residues in FBP-sensitive prokaryotic LDHs. Three-dimensional (3D) models were generated to compare the structure of SmLDH with other LDHs. These models indicated that residues Val187, and especially Tyr190, play a crucial role in the interaction of FBP with the anion pocket of SmLDH. These 3D models of SmLDH are also consistent with a competitive model of SmLDH inhibition in which ATP (inhibitor) and FBP (activator) compete for binding in a well-defined anion pocket. The model of bound ATP predicts a distortion of the nearby key catalytic residue His195, resulting in enzyme inhibition. To investigate a possible physiological role of this allosteric regulation of LDH in schistosomes we made a kinetic model in which the allosteric regulation of the glycolytic enzymes can be varied. The model showed that inhibition of LDH by ATP prevents fermentation to lactate in the free-living stages in water and ensures complete oxidation via the Krebs cycle of the endogenous glycogen reserves. This mechanism of allosteric inhibition by ATP prevents the untimely depletion of these glycogen reserves, the only fuel of the free-living cercariae. Neutralization by FBP of this ATP inhibition of LDH prevents accumulation of glycolytic intermediates when <em>S. mansoni</em> schistosomula are confronted with the sudden large increase in glucose availability upon penetration of the final host. It appears that the LDH of <em>S. mansoni</em> is special and well suited to deal with the variations in glucose availability the parasite encounters during its life cycle.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 7","pages":"Pages 367-378"},"PeriodicalIF":4.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020751924000547/pdfft?md5=3b6f33cd36cc91d150139a0bc5a06cc9&pid=1-s2.0-S0020751924000547-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140140224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the role of individual foxes in environmental contamination with Echinococcus multilocularis through faecal samples","authors":"Abdou Malik Da Silva ,&nbsp;Eve Afonso ,&nbsp;Francis Raoul ,&nbsp;Patrick Giraudoux ,&nbsp;Marina Mergey ,&nbsp;Gérald Umhang ,&nbsp;Sandra Courquet ,&nbsp;Dominique Rieffel ,&nbsp;Laurence Millon ,&nbsp;Jenny Knapp","doi":"10.1016/j.ijpara.2024.03.003","DOIUrl":"10.1016/j.ijpara.2024.03.003","url":null,"abstract":"<div><p>Key parasite transmission parameters are difficult to obtain from elusive wild animals. For <em>Echinococcus multilocularis</em>, the causative agent of alveolar echinococcosis (AE), the red fox is responsible for most of the environmental contamination in Europe. The identification of individual spreaders of <em>E. multilocularis</em> environmental contamination is crucial to improving our understanding of the ecology of parasite transmission in areas of high endemicity and optimising the effectiveness of prevention and control measures in the field. Genetic faecal sampling appears to be a feasible method to gain information about the faecal deposition of individual animals. We conducted a 4 year faecal sampling study in a village that is highly endemic for <em>E. multilocularis,</em> to assess the feasibility of individual identification and sexing of foxes to describe individual infection patterns. Individual fox identification from faecal samples was performed by obtaining reliable genotypes from 14 microsatellites and one sex locus, coupled with the detection of <em>E. multilocularis</em> DNA, first using captive foxes and then by environmental sampling. From a collection of 386 fox stools collected between 2017 and 2020, tested for the presence of <em>E. multilocularis</em> DNA, 180 were selected and 124 samples were successfully genotyped (68.9%). In total, 45 unique individual foxes were identified and 26 associated with at least one sample which tested positive for <em>E. multilocularis</em> (<em>Em</em>(+)). Estimation of the population size showed the fox population to be between 29 and 34 individuals for a given year and 67 individuals over 4 years. One-third of infected individuals (9/26 <em>Em</em>(+) foxes) deposited 2/3 of the faeces which tested positive for <em>E. multilocularis</em> (36/60 <em>Em</em>(+) stools). Genetic investigation showed a significantly higher average number of multiple stools for females than males, suggesting that the two sexes potentially defecated unequally in the studied area. Three partially overlapping clusters of fox faeces were found, with one cluster concentrating 2/3 of the total <em>E. multilocularis</em>-positive faeces. Based on these findings, we estimated that 12.5 million <em>E. multilocularis</em> eggs were produced during the study period, emphasizing the high contamination level of the environment and the risk of exposure faced by the parasite hosts.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 7","pages":"Pages 321-332"},"PeriodicalIF":4.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020751924000535/pdfft?md5=0b1437fe049447413a183795b15df424&pid=1-s2.0-S0020751924000535-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140068344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parvatrema spp. (Digenea, Gymnophallidae) with parthenogenetic metacercariae: diversity, distribution and host specificity in the palaearctic","authors":"Kirill V. Galaktionov ,&nbsp;Anna Gonchar ,&nbsp;Daria Postanogova ,&nbsp;Aleksei Miroliubov ,&nbsp;Semen Yu. Bodrov","doi":"10.1016/j.ijpara.2024.02.002","DOIUrl":"10.1016/j.ijpara.2024.02.002","url":null,"abstract":"<div><p>There are several species of gymnophallid digeneans in the genus <em>Parvatrema</em> that are unique in developing metacercariae that reproduce by parthenogenesis in the second intermediate host. Transmission of these digeneans takes place in coastal ecosystems of the North Pacific and North Atlantic seas. The first intermediate hosts are bivalves, the second ones are gastropods, and the definitive hosts are migratory birds. We integrated data accumulated over 25 years of research and differentiated a complex of five closely related species. They differ in the molluscan second intermediate hosts, distribution ranges, and life cycles patterns. The type I life cycle includes two generations of parthenogenetic metacercariae, followed by development of metacercariae which are invasive for the definitive host. In the type II life cycle, the number of generations of parthenogenetic metacercariae is unlimited, and they can also produce cercariae. These cercariae emerge into the environment and can infect new individuals of the second intermediate host. We conclude that the type I life cycle is a derived option that has evolved as a better fit to transmission in the unstable conditions in the intertidal zone. Another evolutionary trend in <em>Parvatrema</em> is transition from inhabiting the extrapallial space of the gastropod second intermediate host to endoparasitism in its mantle and internal organs. rDNA sequence analysis highlighted that <em>Parvatrema</em> spp. with parthenogenetic metacercariae form a monophyletic clade and suggested the Pacific origin of the group, with two transfers to the North Atlantic and colonisation of new second intermediate host species. Apparently the group formed in the late Pliocene-Pleistocene and diversified as a result of recurrent isolation in inshore refugia during glacial periods. We argue that parthenogenetic metacercariae in <em>Parvatrema</em> may serve as a model for early digenean evolution, demonstrating the first steps of adopting the molluscan first intermediate host and becoming tissue parasites.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 7","pages":"Pages 333-355"},"PeriodicalIF":4.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140059307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sympatry in a nightingale contact zone has no effect on host-specific blood parasite prevalence and lineage diversity","authors":"William Jones ,&nbsp;Radka Reifová ,&nbsp;Jiří Reif ,&nbsp;Petr Synek ,&nbsp;Michal Šíma ,&nbsp;Pavel Munclinger","doi":"10.1016/j.ijpara.2024.03.002","DOIUrl":"10.1016/j.ijpara.2024.03.002","url":null,"abstract":"<div><p>Parasites are a key driving force behind many ecological and evolutionary processes. Prevalence and diversity of parasites, as well as their effects on hosts, are not uniform across host species. As such, the potential parasite spillover between species can significantly influence outcomes of interspecific interactions. We screened two species of <em>Luscinia</em> nightingales for haemosporidian blood parasites (<em>Plasmodium, Leucocytozoon</em> and <em>Haemoproteus</em>) along an approximately 3000 km transect in Europe, incorporating areas of host distant allopatry, close allopatry and sympatry. We found significant differences in infection rates between the two host species, with common nightingales having much lower parasite prevalence than thrush nightingales (36.7% versus 83.8%). This disparity was mostly driven by <em>Haemoproteus</em> prevalence, which was significantly higher in thrush nightingales while common nightingales had a small, but significantly higher, <em>Plasmodium</em> prevalence. Furthermore, we found no effect of proximity to the contact zone on infection rate in either host species. Despite having lower infection prevalence, common nightingales were infected with a significantly higher diversity of parasite lineages than thrush nightingales, and lineage assemblages differed considerably between the two species, even in sympatry. This pattern was mostly driven by the large diversity of comparatively rare lineages, while the most abundant lineages were shared between the two host species. This suggests that, despite the close evolutionary relationships between the two nightingales, there are significant differences in parasite prevalence and diversity, regardless of the distance from the contact zone. This suggests that spillover of haemosporidian blood parasites is unlikely to contribute towards interspecific interactions in this system.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 7","pages":"Pages 357-366"},"PeriodicalIF":4.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140068345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unconventional features in the transcription and processing of spliceosomal small nuclear RNAs in the protozoan parasite Trichomonas vaginalis","authors":"Augusto Simoes-Barbosa,&nbsp;Jully Pinheiro","doi":"10.1016/j.ijpara.2024.03.001","DOIUrl":"10.1016/j.ijpara.2024.03.001","url":null,"abstract":"<div><p><em>Trichomonas vaginalis</em> is a medically important protozoan parasite, and a deep-branching, evolutionarily divergent unicellular eukaryote that has conserved several key features of eukaryotic gene expression. <em>Trichomonas vaginalis</em> possesses a metazoan/plant-like capping apparatus, mRNAs with a cap 1 structure and spliceosomes containing the five small nuclear RNAs (snRNAs). However, in contrast to metazoan and plant snRNAs, the structurally conserved <em>T. vaginalis</em> snRNAs were initially identified as lacking the canonical guanosine cap nucleotide. To explain this unusual condition, we sought to investigate transcriptional and processing features of the spliceosomal snRNAs in this protist. Here, we show that <em>T. vaginalis</em> spliceosomal snRNA genes mostly lack typical eukaryotic promoters. In contrast to other eukaryotes, the putative TATA box in the <em>T. vaginalis</em> U6 snRNA gene was found to be dispensable for transcription or RNA polymerase selectivity. Moreover, U6 transcription in <em>T. vaginalis</em> was virtually insensitive to tagetitoxin compared with other cellular transcripts produced by the same RNA polymerase III. Most important and unexpected, snRNA transcription in <em>T. vaginalis</em> appears to bypass capping as we show that these transcripts retain their original 5′-triphosphate groups. In conclusion, transcription and processing of spliceosomal snRNAs in <em>T. vaginalis</em> deviate considerably from the conventional rules of other eukaryotes.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 6","pages":"Pages 257-266"},"PeriodicalIF":4.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020751924000511/pdfft?md5=2a6e8d2f9a34cd0cc1e7460da5f9ff00&pid=1-s2.0-S0020751924000511-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140059279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gastropod invasions in anthropogenically impacted impoundments in South Africa: Tracing their origins and exploring field evidence of parasite spillback and amplification","authors":"James Omondi Outa,&nbsp;Parthi Bhika,&nbsp;Annemariè Avenant-Oldewage","doi":"10.1016/j.ijpara.2024.02.004","DOIUrl":"10.1016/j.ijpara.2024.02.004","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Invasive snails are associated with ecological problems in freshwater bodies worldwide. However, their impact on the transmission of digenean infections remain underreported. In the present study, 1708 specimens representing four snail species were sampled from four impoundments in the Limpopo River system in South Africa. &lt;em&gt;Gyraulus chinensis&lt;/em&gt; (Planorbidae), &lt;em&gt;Physella acuta&lt;/em&gt; (Physidae) and &lt;em&gt;Pseudosuccinea columella&lt;/em&gt; (Lymnaeidae), which are invasive, were found in all the sampling sites. In contrast, the native lymnaeid &lt;em&gt;Radix natalensis&lt;/em&gt; occurred at only one study site. Digeneans were observed only from &lt;em&gt;R&lt;/em&gt;. &lt;em&gt;natalensis&lt;/em&gt; (prevalence = 49%) and &lt;em&gt;Ps&lt;/em&gt;. &lt;em&gt;columella&lt;/em&gt; (prevalence = 23%). Morphological and genetic analyses revealed four digeneans: &lt;em&gt;Fasciola nyanzae&lt;/em&gt;, &lt;em&gt;Orientocreadium&lt;/em&gt; sp., &lt;em&gt;Petasiger&lt;/em&gt; sp. and &lt;em&gt;Patagifer vioscai&lt;/em&gt;. &lt;em&gt;Pseudosuccinea columella&lt;/em&gt; was infected by the four digeneans while &lt;em&gt;R&lt;/em&gt;. &lt;em&gt;natalensis&lt;/em&gt; harboured only &lt;em&gt;Orientocreadium&lt;/em&gt; sp. and &lt;em&gt;Petasiger&lt;/em&gt; sp. Partial sequences of &lt;em&gt;Orientocreadium&lt;/em&gt; sp. from the current study differed from congeners whose DNA data are available on GenBank, by p-distances of at least 1.84 and 2.2% for 28S and the internal transcribed spacer (ITS) rDNA, respectively. Phylogenetic analyses demonstrated that the present species is sister to &lt;em&gt;Orientocreadium batrachoides&lt;/em&gt;. Genetic and phylogenetic data based on 28S and ITS rDNA suggested that &lt;em&gt;Petasiger&lt;/em&gt; sp. from the present study and isolates of three unidentified &lt;em&gt;Petasiger&lt;/em&gt; spp. from Kenya, Hungary and Australia, were representatives of the same species. This is the first known report of &lt;em&gt;Orientocreadium&lt;/em&gt;, &lt;em&gt;Petasiger&lt;/em&gt; and &lt;em&gt;Patagifer&lt;/em&gt; from &lt;em&gt;Ps&lt;/em&gt;. &lt;em&gt;columella&lt;/em&gt;. The occurrence of &lt;em&gt;F&lt;/em&gt;. &lt;em&gt;nyanzae&lt;/em&gt; in &lt;em&gt;Ps&lt;/em&gt;. &lt;em&gt;columella&lt;/em&gt; indicates spillback from &lt;em&gt;R&lt;/em&gt;. &lt;em&gt;natalensis&lt;/em&gt;. These findings echo the concerns raised in previous studies about the potential role of &lt;em&gt;Ps&lt;/em&gt;. &lt;em&gt;columella&lt;/em&gt; in the amplification of digenean diseases in its introduced range. Phylogenetic analyses of partial sequences of the cytochrome &lt;em&gt;c&lt;/em&gt; oxidase subunit 1 mitochondrial gene (&lt;em&gt;cox&lt;/em&gt;1) showed multiple lineages of &lt;em&gt;Ps&lt;/em&gt;. &lt;em&gt;columella&lt;/em&gt; in North and South America. &lt;em&gt;Pseudosuccinea columella&lt;/em&gt; specimens from the present study belong to an invasive genotype that has spread globally and has been reported from Zimbabwe, Egypt, Portugal, Australia, Argentina, Colombia and New Mexico (USA). &lt;em&gt;Physella acuta&lt;/em&gt; from the current study had a stronger genetic relationship with isolates from Canada and Iceland, than with isolates from other parts of Africa, suggesting several invasion routes into Africa. This is the first known DNA characterisation of &lt;em&gt;G&lt;/em&gt;. &lt;em&gt;chinensis&lt;/em&gt; from Africa. Phylogenetic reconstruction indicated multiple exit events of &lt;","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 6","pages":"Pages 279-301"},"PeriodicalIF":4.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S002075192400050X/pdfft?md5=34b1f0e137f67f931d60f98b5a5ed96a&pid=1-s2.0-S002075192400050X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140059306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The oceanic pleuston community as a potentially crucial life-cycle pathway for pelagic fish-infecting parasitic worms","authors":"Clarisse Louvard ,&nbsp;Russell Q.-Y. Yong ,&nbsp;Scott C. Cutmore ,&nbsp;Thomas H. Cribb","doi":"10.1016/j.ijpara.2023.11.001","DOIUrl":"10.1016/j.ijpara.2023.11.001","url":null,"abstract":"<div><p>Pleustonic organisms form an important part of pelagic ecosystems by contributing to pelagic trophic chains and supporting connectivity between oceanic habitats. This study systematically analysed the trematode community harboured by pleustonic molluscs and cnidarians from offshore Queensland, Australia. Four mollusc and three cnidarian species were collected from beaches of North Stradbroke Island, Queensland. Two mollusc species and all three cnidarians harboured large numbers of hemiuroid metacercariae (Trematoda: Hemiuroidea). Eight taxa from four hemiuroid families (Accacoeliidae, Didymozoidae, Hemiuridae and Sclerodistomidae) were distinguished via molecular sequencing. Four of those taxa were identified to species. All trematode taxa except one didymozoid were shared by two or more host species; five species occurred in both gastropods and cnidarians. It is hypothesised that the life-cycles of these hemiuroids are highly plastic, involving multiple opportunistic pathways of metacercarial transmission to the definitive hosts. Transmission and the use of pleuston by hemiuroids likely varies with sea surface use and ontogenetic trophic shifts of apex predators. The small number of trematode species found in pleuston is consistent with significant ecological specificity, and the inference that other pelagic trematodes use alternative pathways of transmission that do not involve pleustonic organisms. Such pathways may involve i) pelagic hosts exclusively; ii) benthic or demersal hosts exclusively, consumed by apex predators during their dives; or iii) both benthic and pelagic hosts in transmission chains dependent on vertical migrations of prey. The influence of the connectivity of open-ocean ecosystems on parasite transmission is identified as an area in critical need of research.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 6","pages":"Pages 267-278"},"PeriodicalIF":4.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020751923002060/pdfft?md5=9b6490b903a1d47ffb35ccd1a359ea49&pid=1-s2.0-S0020751923002060-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136397311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First use of tissue exudate serology to identify Toxocara spp. infection in food animals","authors":"Sara R. Healy ,&nbsp;Eric R. Morgan ,&nbsp;Joaquin M. Prada ,&nbsp;Grégory Karadjian ,&nbsp;Aurélie Chevillot ,&nbsp;Martha Betson","doi":"10.1016/j.ijpara.2024.02.003","DOIUrl":"10.1016/j.ijpara.2024.02.003","url":null,"abstract":"<div><p><em>Toxocara canis</em> and <em>Toxocara cati</em> are globally distributed, zoonotic roundworm parasites. Human infection can have serious clinical consequences including blindness and brain disorders. In addition to ingesting environmental eggs, humans can become infected by eating infective larvae in raw or undercooked meat products. To date, no studies have assessed the prevalence of <em>Toxocara</em> spp. larvae in meat from animals consumed as food in the UK or assessed tissue exudates for the presence of anti-<em>Toxocara</em> antibodies. This study aimed to assess the potential risk to consumers eating meat products from animals infected with <em>Toxocara</em> spp. Tissue samples were obtained from 155 different food producing animals in the south, southwest and east of England, UK. Tissue samples (<em>n</em> = 226), either muscle or liver, were processed by artificial digestion followed by microscopic sediment evaluation for <em>Toxocara</em> spp. larvae, and tissue exudate samples (<em>n</em> = 141) were tested for the presence of anti-<em>Toxocara</em> antibodies using a commercial ELISA kit. A logistic regression model was used to compare anti-<em>Toxocara</em> antibody prevalence by host species, tissue type and source. While no larvae were found by microscopic examination after tissue digestion, the overall prevalence of anti-<em>Toxocara</em> antibodies in tissue exudates was 27.7%. By species, 35.3% of cattle (<em>n</em> = 34), 15.0% of sheep (<em>n</em> = 60), 54.6% of goats (<em>n</em> = 11) and 61.1% of pigs (<em>n</em> = 18) had anti-<em>Toxocara</em> antibodies. Logistic regression analysis found pigs were more likely to be positive for anti-<em>Toxocara</em> antibodies (odds ration (OR) = 2.89, <em>P</em> = 0.0786) compared with the other species sampled but only at a 10% significance level. The high prevalence of anti-<em>Toxocara</em> antibodies in tissue exudates suggests that exposure of food animals to this parasite is common in England. Tissue exudate serology on meat products within the human food chain could be applied in support of food safety and to identify practices that increase risks of foodborne transmission of zoonotic toxocariasis.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 6","pages":"Pages 303-310"},"PeriodicalIF":4.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020751924000481/pdfft?md5=b7808135a0002430b2ff5a3381312fee&pid=1-s2.0-S0020751924000481-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140065184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature-bounded development of Dirofilaria immitis larvae restricts the geographical distribution and seasonality of its transmission: case study and decision support system for canine heartworm management in Australia","authors":"Peter J. Atkinson ,&nbsp;Mark Stevenson ,&nbsp;Ryan O'Handley ,&nbsp;Torben Nielsen ,&nbsp;Charles G.B. Caraguel","doi":"10.1016/j.ijpara.2024.02.001","DOIUrl":"10.1016/j.ijpara.2024.02.001","url":null,"abstract":"<div><p><em>Dirofilaria immitis</em> is the causative agent of canine heartworm disease. We used the established heartworm development unit (HDU) principle to map the extrinsic incubation period (EIP) of <em>D. immitis</em> in Australia using historical weather data from 2013–2022. We found weather conditions suitable for EIP completion showed substantial seasonality and geographical variability. Whilst a considerable percentage of the Australian territory showed suitable weather conditions to always support EIP completion (17%), only 2.7% of the 2021 Australian human population lived in this region. Therefore, 97% of the population lived in an area that changed its EIP suitability within the study period. EIP completion is required prior to <em>D. immitis</em> transmission, meaning that infection risk of <em>D. immitis</em> is seasonal and location-dependent, being disrupted each year for most of the human population’s dogs. We developed an online, open access tool allowing us to visualise EIP completion across Australia historically and in near real-time. We aim to support veterinarians to make risk-based recommendations for dirofilariosis prevention by using the tool, available at <span>https://heartworm-mapping.adelaide.edu.au/shiny/</span><svg><path></path></svg>.</p></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"54 6","pages":"Pages 311-319"},"PeriodicalIF":4.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S002075192400047X/pdfft?md5=69d21169a4ae16642f3c3ed6a6323d45&pid=1-s2.0-S002075192400047X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140049408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}