International journal for parasitology最新文献

{"title":"Host whole genome sequence data represent an untapped resource for characterising affiliated parasite diversity","authors":"Sarah Nichols,&nbsp;Andrea Estandía,&nbsp;Catherine M. Young,&nbsp;Lucy S. Knowles,&nbsp;Vaidas Palinauskas,&nbsp;Beth Okamura,&nbsp;Sonya M. Clegg","doi":"10.1016/j.ijpara.2025.104768","DOIUrl":"10.1016/j.ijpara.2025.104768","url":null,"abstract":"<div><div>Parasites are ubiquitous and exert varied ecological and evolutionary pressures on their hosts. Yet, characterising parasite diversity and distributions can be challenging and costly. Leveraging existing data to identify parasites is thus an attractive alternative. High-throughput sequencing (HTS) can generate whole genome sequence (WGS) data which are increasingly freely available in public repositories and represent an untapped resource for characterising parasites affiliated with hosts. In this study, we examine WGS data generated for the silvereye (<em>Zosterops lateralis</em>), to identify endogenous eukaryotic parasites that were inadvertently captured during host sequencing. We compared detection of parasite genera by this approach with detection via 18S metabarcoding. Mining WGS data for parasite DNA revealed the broadest range of genera. Results were verified by traditional microscopy of blood slides and conducting a targeted multiplex Polymerase Chain Reaction (PCR) for haemosporidian parasites. Detection of haemosporidians was largely consistent across microscopy, multiplex PCR and WGS data while 18S metabarcoding entirely failed to detect this group of parasites. Our results demonstrate that existing WGS datasets can be used to estimate endoparasite diversity and provide greater insights on diversity than metabarcoding whilst also avoiding the costs and challenges of direct sampling. We provide a framework outlining opportunities and constraints to consider when mining WGS data to identify parasite sequences. The framework particularly stresses the influences of sequencing depth, database completeness, and methodological biases. Our findings demonstrate how repurposing existing WGS data can provide a cost-effective and informative means of unravelling complex host-parasite interactions in future disease ecology studies.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104768"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145932802","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":"Functional characterization of secreted Schistosoma mansoni serpin SmSPI reveals factor XIIa inhibition as evidenced by biochemical and human plasma assays and supported by AI-assisted structural modeling","authors":"Lukáš Konečný,&nbsp;Kristýna Peterková,&nbsp;Ingrid Hrachovinová,&nbsp;Alex Loukas,&nbsp;Tomáš Macháček,&nbsp;Jan Dvořák,&nbsp;Lucie Jedličková","doi":"10.1016/j.ijpara.2026.104808","DOIUrl":"10.1016/j.ijpara.2026.104808","url":null,"abstract":"<div><div><em>Schistosoma mansoni</em> persists in host vasculature for years without inducing thrombosis or excessive inflammation, suggesting active interference with host serine proteases involved in hemostasis and immunity. To explore the mechanisms behind these evasion strategies, we investigated <em>S</em>. <em>mansoni</em> Serine Protease Inhibitor (serpin), SmSPI, previously described as a circulating antigen. Our gene expression profiling revealed SmSPI to be the most highly expressed parasite serpin in intravascular life stages, including adult worms and eggs. This indicates its constant accessibility to host proteolytic pathways at multiple host–parasite interfaces (in the bloodstream, liver, and intestine), which was confirmed by immunolocalization experiments. To identify potential host targets of SmSPI, we used ColabFold-based structural prediction to screen 34 candidate host serine proteases involved in immune-, digestive-, and hemostasis-related processes. The resulting <em>in silico</em> predictions were validated by enzymatic activity assays, which demonstrated that recombinant SmSPI effectively inhibited several host proteases, including cathepsin G, urokinase, and pancreatic elastase, with weaker inhibition observed against chymotrypsin. Importantly, the SmSPI also exhibited significant inhibition of Factor XIIa (FXIIa), a key initiator of the contact activation system in the intrinsic coagulation pathway. To confirm the functional relevance of this interaction, we performed activated partial thromboplastin time (aPTT)-based assays in human plasma. Plasma was preincubated with rSmSPI, which resulted in a significant prolongation of thrombin generation time. Furthermore, this effect was dependent on the concentration of FXII present in human plasma, confirming the specificity of this inhibition. These results establish SmSPI as a multifunctional host-interacting serpin with immunomodulatory and targeted anticoagulant properties. Notably, its ability to inhibit FXIIa identifies SmSPI as the first helminth-derived inhibitor of the contact activation system, making the protein a promising candidate for future anticoagulant therapies designed to limit thrombosis while preserving normal hemostasis.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104808"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147271058","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":"Be afraid, be very afraid: how host cues determine attractiveness to parasite infectious stages and the resulting infection loads","authors":"J. Koprivnikar,&nbsp;L.M. Santos,&nbsp;P.T.J. Johnson","doi":"10.1016/j.ijpara.2026.104771","DOIUrl":"10.1016/j.ijpara.2026.104771","url":null,"abstract":"<div><div>The likelihood of infection is influenced by both innate and environmental factors, including host defences and contacts with infectious stages. Although theory predicts that motile parasites ought to select susceptible host species, few studies have considered parasite preference among individuals of a single host species. By experimentally manipulating the presence, activity, and susceptibility of tadpoles, we tested the importance of host cues (chemical and mechanical) and host resistance on intraspecific host choice by free-swimming trematode (flatworm) cercariae. Cercariae could ‘choose’ among four chambers with these combinations in a first set of trials but could not contact (and infect) hosts. In a second set of trials with the same tadpoles, cercariae were allowed to select and infect hosts, allowing us to analyze the relationship between initial parasite choice and subsequent infection establishment. Cercariae showed a trend for greater attraction to anesthetized tadpoles over negative controls (empty chambers), suggesting the use of chemical cues to locate hosts, but were most attracted to active (non-anesthetized) tadpoles, indicating an important role for host movement. Cercariae showed no preference for tadpoles subjected to an immunosuppressive treatment, despite their greater susceptibility to infection. Importantly, the initial number of cercariae that chose each tadpole in the first round positively predicted parasite load in the second round of exposures. Highly active hosts, which initially attracted the most cercariae, ultimately supported the highest infections, either because parasites made ‘good’ host choices, or, alternatively, prior host exposure (without actual infection) increased susceptibility.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104771"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145984741","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":"Treatment-refractory giardiasis is predominantly an imported infection from South Asia associated with Giardia sub-assemblage BIII: a five-year study from the Czech Republic","authors":"Aneta Perglerová,&nbsp;Ivana Zicklerová,&nbsp;František Stejskal,&nbsp;Filip Weisz,&nbsp;Milan Trojánek,&nbsp;Magdalena Uzlíková,&nbsp;Eva Nohýnková,&nbsp;Pavla Tůmová","doi":"10.1016/j.ijpara.2026.104821","DOIUrl":"10.1016/j.ijpara.2026.104821","url":null,"abstract":"<div><div>Giardiasis is a cosmopolitan parasitic infection caused by a protozoan pathogen <em>Giardia intestinalis</em>. A high number of failures complicates the metronidazole (MTZ) treatment. However, long-term studies characterising the parasites associated with MTZ treatment failures are lacking. This study was designed to map <em>Giardia</em> genotypes, clinical manifestations and geographical origin of giardiasis in a patient cohort from the Czech Republic. A multilocus genotyping was applied to 93 <em>Giardia</em> DNA isolates collected over five years in a tertiary care hospital diagnostic facility, and corresponding patient data, including the treatment outcomes, were evaluated. We found that treatment-refractory giardiasis (32.9% of infections) was always symptomatic, associated with South Asian origin and caused mainly by sub-assemblage BIII parasites. This study confirms the limited efficacy of MTZ treatment, especially in travellers returning from South Asia.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104821"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147456922","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":"Experimental infection of immunosuppressed mice demonstrates freeze tolerance of Trichinella chanchalensis","authors":"Cody J. Malone,&nbsp;Vladislav A. Lobanov,&nbsp;W. Brad Scandrett,&nbsp;Robyn Ostrander,&nbsp;Kelly Konecsni,&nbsp;Emily J. Jenkins","doi":"10.1016/j.ijpara.2026.104822","DOIUrl":"10.1016/j.ijpara.2026.104822","url":null,"abstract":"<div><div><em>Trichinella chanchalensis</em> (T13) remains poorly characterized, limiting understanding of its biology, freeze-tolerance, and zoonotic potential. One major challenge is that infective first-stage larvae can only be obtained from naturally exposed wildlife in northern North America, which often harbour co-infections with other <em>Trichinella</em> taxa. Therefore, we used next-generation sequencing (NGS) to identify naturally infected wolverines with high proportions of T13 larvae. We recovered larvae from muscle tissue previously frozen at −20 °C for up to 15 months and orally inoculated a total of 55 CD-1 and BALB/c mice, including immunocompetent and immunosuppressed groups, with doses of 21-581 larvae. Mouse carcasses were digested, and recovered larvae were genotyped using NGS. Establishment and recovery of <em>T. chanchalensis</em> larvae were consistently low, with only two larvae recovered from one BALB/c mouse in a pure infection and 2-913 larvae from immunosuppressed mice as mixed infections, despite good recovery of larvae of <em>T. nativa</em> and <em>Trichinella</em> T6. On repassaging in mice, only two <em>T. chanchalensis</em> larvae were recovered after the second passage. These results suggest poor adaptation of <em>T. chanchalensis</em> to laboratory mice, despite immunosuppression, and/or lower freeze-tolerance of <em>T. chanchalensis</em> compared to <em>T. nativa</em> and <em>Trichinella</em> T6. Differences in cold adaptation among northern <em>Trichinella</em> taxa likely reflect ecological and evolutionary pressures, with <em>T. nativa</em> considered the most freeze-tolerant, while T6 and <em>T. chanchalensis</em> exhibit comparatively lower tolerance. Understanding the biology and freeze-tolerance of <em>T. chanchalensis</em> is important for food safety and for developing One Health-informed surveillance to protect northern communities reliant on game meat.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104822"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147443515","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":"Identification of Chaetozone setosa (Cirratulidae) as the definitive host in the life cycle of Parvicapsula pseudobranchicola infecting Atlantic salmon (Salmo salar)","authors":"Ásthildur Erlingsdóttir,&nbsp;Árni Kristmundsson","doi":"10.1016/j.ijpara.2026.104799","DOIUrl":"10.1016/j.ijpara.2026.104799","url":null,"abstract":"<div><div><em>Parvicapsula pseudobranchicola</em> is a marine myxozoan parasite of high significance to Atlantic salmon (<em>Salmo salar</em>) aquaculture, particularly in northern regions such as Norway and Iceland, where outbreaks have been reported with increasing frequency and severity in recent years. In this study, we aim to resolve the life cycle of <em>P. pseudobranchicola</em> by screening benthic invertebrate communities in areas with known infection pressure in salmon farms as well as performing a transmission trial using post-smolt Atlantic salmon and polychaetes. Sediment samples were collected using a Van Veen grab sampler, covering a 0.025 m² area at each sample site. Polychaetes found were subjected to microscopic investigation, PCR, Sanger sequencing, histology and in situ hybridization. Fish were challenged with actinospores using two different methods. The polychaete <em>Chaetozone setosa</em> was identified as the definitive host of <em>P. pseudobranchicola</em>. Actinospores of morphotype saccimyxon, measuring 5–6 µm in diameter are described. Each spore contained three spherical polar capsules, approximately 0.7–1.0 µm in diameter. Four of the 20 challenged fish (20%) tested positive for parasite DNA in blood samples by PCR. By identifying and confirming the polychaete <em>Chaetozone setosa</em> as the definitive host of <em>Parvicapsula pseudobranchicola</em>, we resolve the sixth known marine myxozoan life cycle. These results provide immediate utility. Life cycle resolution enables targeted surveillance and site-specific risk zoning as mitigation for parvicapsulosis, that should reduce impact on fish welfare and losses from the disease.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104799"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146051970","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 miRNAome of the honey bee parasite, Varroa destructor, shows sex-specific expression of miRNA clusters across life stages","authors":"Rebecca C. McKee,&nbsp;James E. Damayo,&nbsp;Zoe E. Smeele,&nbsp;Antoine Felden,&nbsp;Philip J. Lester,&nbsp;Alyson Ashe,&nbsp;Emily J. Remnant","doi":"10.1016/j.ijpara.2026.104804","DOIUrl":"10.1016/j.ijpara.2026.104804","url":null,"abstract":"<div><div>The honey bee mite, <em>Varroa destructor</em>, is one of the biggest threats to the western honey bee, <em>Apis mellifera</em>. MicroRNAs (miRNAs) are important regulators of gene expression, playing roles in development, sex differentiation, and reproduction, yet little is known about their expression throughout the <em>Varroa</em> mite lifecycle. Here we identify the complete set of miRNAs in <em>V. destructor</em> throughout its lifecycle by sequencing the small RNAs of male and female mites. We identify 170 precursor miRNAs, including 88 novel miRNAs that appear specific to mites. miRNA expression varies significantly between life stages, revealing miRNAs specific to developmental stage and sex. Reproductive adult females (foundresses) show an expression pattern that is distinct from other adult females, with similarities to eggs and early juvenile stages, indicating a significant role for miRNA regulation in reproduction and early development. This expression is largely driven by three miRNA clusters (vde-miR-92, vde-miR-279/35, vde-miR-35/nov-7) containing 16 miRNAs that are significantly upregulated in foundress mites. Additionally, a cluster of three miRNAs from a novel miRNA family (vde-miR-nov-1) are significantly upregulated in all female life stages compared to males. The expression patterns of the vde-miR-nov-1 family suggest a potential role for miRNA regulation in sex differentiation and female development. Our results indicate that miRNA regulation has an important role in the biology and development of <em>V. destructor.</em> Characterising the downstream impacts of miRNAome expression will enable a better understanding of mite development and reproductive processes. The identification of novel, <em>Varroa-</em>specific miRNAs may provide targets for future control methods.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104804"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146179340","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":"Aims and scope and Editorial board","authors":"","doi":"10.1016/S0020-7519(26)00160-8","DOIUrl":"10.1016/S0020-7519(26)00160-8","url":null,"abstract":"","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 8","pages":"Article 104929"},"PeriodicalIF":3.3,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148660438","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":"Cryptic Biomphalaria spp. diversity, spatial population structure and contrasting schistosome infection patterns in the Lake Albert region.","authors":"Julius Tumusiime, Casim Umba Tolo, Grace Kagoro-Rugunda, Daisy Namirembe, Cyril Hammoud, Christian Albrecht, Tine Huyse","doi":"10.1016/j.ijpara.2026.104927","DOIUrl":"10.1016/j.ijpara.2026.104927","url":null,"abstract":"<p><p>Biomphalaria snails are intermediate hosts of Schistosoma mansoni, and their distribution predicts where intestinal schistosomiasis may occur. Here, we investigated the genetic diversity and distribution patterns of Biomphalaria spp. in the Lake Albert region and assessed their role in the transmission of schistosomes. Snails (n = 6869) were screened for schistosome infections using cercariae shedding and molecular techniques. In total, 29,670 Biomphalaria snails were collected, 90% of which were in the upland sites. For a subset of snails (n = 184) we sequenced a partial cytochrome c oxidase subunit one (COX1) fragment for phylogeographic analyses. Biomphalaria sudanica, Biomphalaria pfeifferi and Biomphalaria stanleyi were identified, with the former two species having haplotypes shared at the lake and upland sites. We also report the presence of a cryptic lineage, tentatively named B. cf. pfeifferi, awaiting further description. Molecular assays revealed higher overall prevalence of S. mansoni (1.9%) and S. rodhaini (1.12%) among Biomphalaria spp. (n = 1619) than inferred from cercarial shedding (0.66%). However, S. mansoni occurred exclusively at lake and nearby stream sites and was hosted predominantly by B. sudanica (24.7%, 22/89) and B. pfeifferi (5.4%; 5/147), while S. rodhaini, hosted mainly by B. cf. pfeifferi, was widely distribution in upland sites allopatric to S. mansoni. The wet season (October and November) had the highest S. mansoni prevalence. We argue that the lack of S. mansoni in upland sites reflects a more nuanced situation than simply the absence of suitable host snails, and suggest taxonomic revision of the B. pfeifferi complex.</p>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":" ","pages":"104927"},"PeriodicalIF":3.3,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148584383","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":"Good parasites make bad hosts: why is hyperparasitism uncommon among metazoan parasites.","authors":"Juan T Timi, Robert Poulin","doi":"10.1016/j.ijpara.2026.104926","DOIUrl":"10.1016/j.ijpara.2026.104926","url":null,"abstract":"<p><p>Hyperparasitism, in which a parasite exploits another parasite, represents a logical extension of parasite diversity and complexity within ecological networks. While common and ecologically significant in microbial systems, hyperparasitism among metazoan parasites appears comparatively rare. This discrepancy is intriguing given the high diversity and frequent co-occurrence of parasites within hosts. Here, we compile and review published cases of hyperparasitism involving metazoan parasites to assess their taxonomic distribution and ecological characteristics. We identify a wide range of hyperparasitic strategies, including opportunistic associations and highly specialized interactions. However, many published cases appear to be accidental or rare, suggesting that true hyperparasitism is even less frequent than reported. We argue that the relative rarity of hyperparasitism among metazoan parasites results from a combination of ecological and evolutionary constraints, including low encounter probabilities, dependence on multiple hosts, parasite aggregation, limited trophic accessibility, structural simplicity of parasite bodies, the presence of dual immune barriers imposed by both host and parasite, and, especially, energetic scaling constraints. Together, these factors restrict the conditions under which hyperparasitism can evolve and persist. Therefore, despite the vast diversity of parasites, their suitability as hosts is limited, and thus they rarely serve as hosts for other metazoan parasites. In this context, \"good parasites\" may indeed make \"bad hosts.\"</p>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":" ","pages":"104926"},"PeriodicalIF":3.3,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148455806","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}