Helminth communities of the invasive Podarcis muralis and the native P. tauricus were investigated in southern Ukraine based on newly collected material and historical data. A total of nine P. muralis and 20 P. tauricus specimens were examined. Two helminth species were recorded in each lizard host. In P. muralis, the nematode Spauligodon saxicolae and cystacanths of the acanthocephalan Centrorhynchus globocaudatus were found, while S. saxicolae and the cestode Oochoristica tuberculata were found in P. tauricus. Historical data from 116 P. tauricus collected between 1951 and 1990 revealed a total of nine helminth taxa, most of which occurred at low prevalence. The occurrence of S. saxicolae in both host species suggests that invasive and native lacertids in southern Ukraine may share part of the same local parasite pool. However, larger spatially replicated studies are required to evaluate parasite exchange and transmission dynamics.

Using an integrative taxonomic approach, we describe two new species of Monopisthocotyla, Mymarothecioides leporini n. sp. and Mymarothecioides paranaensis n. sp., parasitising the gills of anostomid fishes from the Jaguaribe River and Paraná River basins, Brazil. These descriptions represent the first record of species of Mymarothecioides in hosts of the family Anostomidae. Mymarothecioides leporini n. sp. is distinguished by a male copulatory organ (MCO) with a spoon-shaped distal portion and a ventral bar with an ornamented anteromedial process. Mymarothecioides paranaensis n. sp. differs from its congeners by possessing a sclerotised, arcuate MCO with a rounded tip and a rectangular-shaped basal flap. Molecular analyses of Large Subunit ribosomal DNA (LSU rDNA) and Mitochondrial Region of Cytochrome C Oxidase subunit 1 (COI mtDNA) markers support the validity of both taxa, placing them as distinct molecular operational taxonomic units (MOTUs). High genetic distances (17.8%–18.7% for COI) confirmed the separation between the two new species. Additionally, this study provides the first molecular characterisation for the genus. These findings expand the known geographical distribution and host range of Mymarothecioides, contributing to the knowledge of dactylogyrid diversity in Neotropical freshwater systems.

Cestode larvae of Anthobothrium sp. were collected from the caecum and stomach of the common squid Loligo vulgaris Lamarck, 1798 (Cephalopoda: Loliginidae) in Tunisian waters (Bay of Bizerte and Gulf of Tunis), with the highest prevalence recorded in the Gulf of Tunis (52.94%). These specimens were morphologically characterised and compared to previously described Anthobothrium larvae from other hosts. Molecular analysis using 28S ribosomal DNA (rDNA), combined with phylogenetic reconstruction (maximum likelihood and pairwise distances), revealed that the sequences cluster with adult specimens from several elasmobranch species. These definitive hosts include Carcharhinus obscurus and Carcharhinus limbatus, which are common in Tunisian waters, thereby providing new insights into the potential life cycle of this parasite. Loligo vulgaris represents a new host record for Anthobothrium sp. larvae and appears to be its preferred cephalopod host in the Mediterranean. Finally, a comprehensive checklist of metacestodes recorded in L. vulgaris is provided.

The limestone soil of the Yucatán Peninsula is highly permeable, allowing fluvial waters to filter into the aquifer, resulting in the absence of rivers on the surface and the formation of underground reservoirs that, on some occasions, open to the surface, forming the so-called cenotes (or sinkholes). Information about the freshwater fish parasite diversity of cenotes in the Yucatán Peninsula is scarce. Only 50 cenotes of the approximately 9,000 occurring in the peninsula have been sampled to assess the fish parasite fauna. Available information predates the molecular era and is based on morphological assessments solely. Here, specimens of 7 fish species were sampled in 15 localities distributed along an area known as the ‘Ring of Cenotes’, a depression associated with the Chicxulub crater formed by the impact of a meteorite. Trematode metacercariae were collected, sorted by morphotype, and sequenced for the partial 28S rRNA and/or COI mtDNA genes. Twelve trematode metacercariae were identified, seven to species level and five to genus or family level, since they did not match any known sequenced species available in the BLAST search. Metacercariae corresponded to three families; Diplostomidae was the most diverse with eight taxa. The cichlid Mayaheros urophthalmus harboured the greatest number of taxa, with nine. Three species of Clinostomum were identified molecularly in what previous findings considered a single species on morphological grounds. The importance of continually expanding the genetic library of larval trematodes and establishing links between adults and larval forms to fully assess and understand trematode diversity is discussed.

The structure of the praesoma in the acanthocephalan Arhythmorhynchus teres Van Cleave, 1920 at the middle acanthella I stage has been examined by light and transmission electron microscopy methods. Acanthocephalan specimens were retrieved from naturally infected intermediate hosts, Bulychevia ochotensis (Brandt, 1851) (Amphipoda, Talitridae). In the studied acanthellae, the primordia of the proboscis receptacle, proboscis, circular muscles, proboscis retractor, and cerebral ganglion are clearly differentiated in the praesoma. The tegument contained giant nuclei arranged into annular rows oriented transversely to the longitudinal axis of the body. At the anterior pole of the acanthellae, three apical nuclei were present; they were densely grouped and considerably smaller than the giant nuclei. The proboscis primordium consisted of vertical cytoplasmic strands (hook primordia) that, together with the basal cytoplasm of the anterior pole tegument, formed an outgrowth protruding into the acanthella’s body cavity. Thus, similar to the other members of the class Palaeacanthocephala, the proboscis of acanthocephalan A. teres is initially formed in an inverted state. Two layers of muscles surround the proboscis: the proboscis retractor and a layer of circular musculature that closely surrounds the developing proboscis, forming a muscular sheath. Six nuclei are found in certain areas of the cytoplasm of the circular muscles. The tubular proboscis retractor surrounds the proboscis together with the primordium of circular musculature, extends around the cerebral ganglion, and attaches to the base of the proboscis receptacle. Four nuclei at the apex of the inverted proboscis were located in the cytoplasm of the hook primordia, while another two nuclei were in the cytoplasm of the circular musculature primordium.

A new nematode population of the genus Ficophagus was recovered from figs of Ficus amplissima from ICAR-Indian Agricultural Research Institute, New Delhi, India. It is described herein as Ficophagus siddiqii n. sp., distinguished among all known species of the genus by its slender, cylindrical female body and presence of four faint lateral incisures at mid-body, with the outermost pair being the most prominent; a short post-uterine sac (PUS; 5.0–10 μm), a secretory-excretory pore situated near the lips, amoeboid sperm, and three pairs of subventral papillae on the male tail. Conoid tail in both sexes; the male tail tip broadly rounded without mucro and female tail tip pointed or spike-like projection. Gubernaculum absent, rose-thorn-shaped spicules with relatively high condylus – rounded to truncate. This species is also distinguished by its biogeography and host plant, as it is collected from Ficus amplissima. Further, it is characterised by molecular sequences of 18S SSU, 28S D2–D3, Cytochrome c Oxidase Subunit I (COI), and Internal Transcribed Spacer (ITS). Molecular comparisons of the Indian population of Ficophagus siddiqii n. sp. with other Ficophagus species using D2–D3, SSU, COI, and ITS sequences revealed a clear separation of Ficophagus siddiqii n. sp. from other Ficophagus species.

Trichinella spiralis (T. spiralis) infection induces oxidative stress, inflammation, and increased larval burden. Albendazole (ABZ) remains the standard treatment; however, adjunct therapies may enhance host protection. Thus, this study aimed to comparatively evaluate, for the first time, the individual therapeutic and antioxidant effects of resveratrol (RSV) and sulforaphane (SFN) relative to standard ABZ therapy against trichinellosis, along with the associated biochemical and histopathological changes in mice. Mice were divided into five main groups: (I): Non-infected, non-treated; (II): Infected, non-treated; (III): Infected mice treated with ABZ; (IV): Infected mice treated with RSV; and (V): Infected mice treated with SFN. Drug efficacy was evaluated through parasitological, biochemical, and histopathological analyses. Infection resulted in a significant rise in larval burden, oxidative stress, and pro-inflammatory cytokines, with disruption of antioxidant defences. ABZ produced the greatest reduction in larval load. Both RSV and SFN significantly reduced oxidative stress and inflammatory cytokines compared to ABZ alone. RSV exerted a more pronounced effect on sirtuin enzyme isoform 1 (SIRT1) expression. SFN showed stronger activation of antioxidant defense mechanisms and increased solute carrier family 7-member 11 (SLC7A11) expression. In conclusion, RSV and SFN effectively mitigate T. spiralis-induced oxidative stress and inflammation and may represent promising candidate agents for future adjunct therapy with ABZ in the management of trichinellosis, pending evaluation in combination.

Urogenital schistosomiasis remains a significant public health problem among school-aged children in Tanzania despite ongoing preventive chemotherapy. This study determined the prevalence of laboratory-confirmed Schistosoma haematobium infection and assessed knowledge and behavioural factors associated with infection among primary school children in an urban district of Tanzania. A school-based cross-sectional analytical study was conducted among 384 children selected using a multistage sampling technique. Data were collected using a structured interviewer-administered questionnaire and laboratory examination of urine specimens by the standard urine filtration technique. Logistic regression analyses were performed to identify factors independently associated with laboratory-confirmed infection. The overall prevalence of S. haematobium infection was 11.2% (95% CI: 8.1–14.4), with 90.7% of infected children having light-intensity infections. Younger children aged 9–11 years were at significantly higher risk of infection than older children. Previous schistosomiasis diagnosis (adjusted odds ratio (AOR) = 4.15, 95% confidence interval (CI): 1.52–11.33; p = 0.005) and unemployment of the head of household (AOR = 5.92, 95% CI: 1.16–30.32; p = 0.033) were independently associated with infection. Overall, 45.3% of participants demonstrated good knowledge of urogenital schistosomiasis; however, infection persisted despite relatively high levels of awareness. Urogenital schistosomiasis remains endemic among primary school children in this urban setting, indicating ongoing transmission despite school-based control programmes. Strengthening integrated control strategies that combine preventive chemotherapy with health education, improved water, sanitation, and hygiene, and interventions that reduce exposure to contaminated freshwater is essential to accelerate progress towards schistosomiasis elimination.

We took advantage of rhinoceros translocations and entomological studies in the 1990s to elucidate some aspects of the biology of Stephanofilaria in Kenya, which remains largely undocumented. Blood samples from 88 black and 27 white rhinos were screened for microfilariae during routine haematology. Microfilariae matching S. dinniki were found in three individual black rhinos on single occasions and were not found in white rhinos; the parasite was not transmissible to tsetse or laboratory mice. Thousands of proboscides of 19 species of Stomoxyinae and other Diptera were dissected from Nairobi National Park and Solio Ranch to detect larval forms of filarial nematodes. Stephanofilaria was found in seven Stomoxys species at low prevalence (< 2%, mean of nine per fly), with a few similar parasites found in two Haematobosca species. Larval filaria were measured for basic landmarks and were described through light microscopy. This information now provides a foundation for more detailed studies of the life cycle of this parasite.

A new needle nematode, Longidorus parasabalanicus sp. nov. (Nematoda: Longidoridae), was collected from the rhizosphere of Astragalus spp. in mountainous areas of northern Iran. The species is characterised by a medium-sized body (female 4.0–4.8 mm; male 4.3–5.1 mm), lip region anteriorly flattened and laterally rounded, ca 12.5–14.5 μm wide, and separated from the body by a shallow depression, amphidial fovea pocket-shaped without basal lobes, moderate odontostyle (75.0–84.0 μm) and odontophore (50.0–58.0 μm), and guiding ring located at 27–33 μm from the anterior end. The pharyngeal bulb has the common arrangement of pharyngeal glands. Females have a vulva almost equatorial (V = 50–56%), short tail rounded to bluntly conoid, 41.0–47.0 μm long (c = 89.0–113.0, c′ = 0.9–1.2), with two pairs of caudal pores and a broadly rounded terminus with distinct radial lines in the hyaline region. Males are common, with spicules 68.0–80.0 μm long and eight to ten ventromedian supplements. All four juvenile stages are present, with the first-stage juvenile having a conoid tail, dorsoventrally curved with a rounded terminus. The polytomous codes for the new species are: A23-B2-C3(2)-D3-E1-F2-G1(2)-H12-I2-J1-K6. Morphologically, L. parasabalanicus sp. nov. is most similar to L. sabalanicus, and together with L. tabrizicus and L. paratabrizicus, belongs to a closely related species complex, from which it can be distinguished by a combination of subtle but consistent morphometric characters. Molecular phylogenetic analyses based on D2–D3 expansion segments of 28S rDNA, partial 18S rDNA, ITS1, and mitochondrial COI sequences support its recognition as a distinct lineage within the genus. Phylogenetic trees recover the new species in a well-supported clade with L. sabalanicus and other closely related species from Iran and the Mediterranean. This study provides comprehensive morphological, morphometric, and molecular data for delimiting the new species and contributes to understanding Longidorus diversity in Iran and adjacent regions.

Wood mice (Apodemus sylvaticus), yellow-necked mice (A. flavicollis) and voles (Microtus agrestis) from the British Isles and from the European mainland have been reported to carry a cestode referred to as Hymenolepis murissylvatici. However, based on the morphometrics of diagnostic characters, Prokopič (1967) showed that isolates of this species from wood mice were indistinguishable from a species parasitizing a range of birds, which he referred to as Variolepis crenata. Subsequently, Vaucher et al (2003) showed that this was not a valid conclusion. Here, we track the key nomenclature changes associated with isolates from rodents and birds. Following recent revisions of genera in the Hymenolepididae, including the reinstatement of Variolepis as a valid genus, and based on both published morphometric criteria and 28S rDNA sequencing, we conclude that synonymy of H. murissylvatici from rodents with V. crenata from birds is not safe. Instead, we propose that until molecular genetic analyses of isolates from woodpeckers, passerine birds, and rodents have been completed, reference to this species as Variolepis murissylvatici comb. nov. is currently more appropriate and justified by available information. We review studies recording V. murissylvatici in wild rodents, and experiments in which the host-parasite relationship of this cestode was explored in laboratory mice and identify directions for future exploration of the biology of this enigmatic species.

This study aimed to (1) assess the diversity of Gyrodactylus species infecting Day’s mystus, Mystus bleekeri (Siluriformes: Bagridae), in northern India; (2) provide genetic resources for two new species to support taxonomy, phylogeny, and diagnostics; and (3) compile an annotated checklist of Gyrodactylus species from Indian freshwater fishes. Between 2022 and 2025, two new species, Gyrodactylus octoacanthicus n. sp. and Gyrodactylus ascia n. sp., were recovered and described from the skin and gills of M. bleekeri. Species delimitation included the integration of morphometric analysis of sclerotised haptoral and reproductive structures with sequencing of the complete ITS rDNA region (ITS1–5.8S–ITS2) and partial 28S rDNA. Molecular comparisons showed substantial divergences from previously described species in two markers, ITS rDNA (19.12% in G. octoacanthicus n. sp.; 18.07% in G. ascia n. sp.) and 28S rDNA (16.83% in G. octoacanthicus n. sp.; 8.79% in G. ascia n. sp.), exceeding standard species-delineation thresholds. The newly compiled checklist included 17 taxonomically valid Indian species (including the two new species), of which sequence data are available for only seven, and eight nominal or undescribed species that were considered unavailable names due to non-compliance with the International Code of Zoological Nomenclature. The replacement names Gyrodactylus pandeyi nom. nov. and Gyrodactylus fossilisii nom. nov. were proposed for the junior homonyms, Gyrodactylus mizellei Dubey, Gupta & Agrawal, 1990 and Gyrodactylus gussevi Dubey, Gupta & Agrawal, 1990, respectively. These findings highlighted significant gaps in Indian gyrodactylid diversity and taxonomy and underscored the need for further integrative studies on parasite diagnostics, aquaculture-health management, and freshwater biodiversity conservation in India.

We report a new commensal relationship between oerstediid nemerteans and deep-sea ascidians. A total of six nemertean individuals were collected from the peribranchial cavities of several Styelidae ascidians attached to small rocks at bathyal depths (1,400–1,409 m) off northeastern Japan in the northwestern Pacific Ocean. Phylogenetic analyses based on combined mitochondrial cytochrome c oxidase subunit I (COI), 16S rRNA, histone H3, 18S rRNA, and 28S rRNA gene sequences placed this species within the ‘Clade Gononemertes’ of the hoplonemertean family Oerstediidae. Previous records of commensalism between nemerteans and deep-sea ascidians are restricted to the genus Culeolus (Pyuridae). The present finding therefore suggests that ascidian-host diversity may be greater in Oerstediidae than previously recognised.

Strongyloides stercoralis is a soil-transmitted helminth capable of lifelong persistence through autoinfection, placing individuals with latent infection at risk during immunosuppression. Although corticosteroids are recognized triggers for hyperinfection and dissemination, population-level data quantifying these risks remain limited. We conducted a multicentre retrospective cohort study using the TriNetX Global Collaborative Network. Adults with laboratory-confirmed latent Strongyloides infection (positive IgG serology) were included, while patients with active disease were excluded. Corticosteroid exposure was defined as receipt within 30 days of the index test. Propensity score matching compared outcomes between patients with latent infection who did and did not receive corticosteroids. Secondary analyses compared steroid-exposed patients with and without Strongyloides and evaluated prophylactic ivermectin among steroid-exposed seropositive patients. The primary outcome was 90-day mortality; secondary outcomes included sepsis, bacteraemia, and ICU admission. Cox proportional hazards models evaluated time-to-event outcomes. Among patients with latent infection, 494 received corticosteroids, and 1,501 did not. After matching, corticosteroid exposure was associated with increased 90-day mortality (9.4% vs. 4.7%; OR 2.10, 95% CI 1.19–3.72), sepsis (OR 2.05, 95% CI 1.17–3.58), bacteraemia (OR 2.13, 95% CI 1.41–3.23), and ICU admission (OR 2.85, 95% CI 2.03–3.98). In Cox models, corticosteroid exposure remained independently associated with higher hazards of 90-day mortality (HR 3.16, 95% CI 2.01–5.02) and sepsis (HR 3.01, 95% CI 1.72–5.23). Prophylactic ivermectin was associated with a lower risk of a composite outcome (12.9% vs. 27.1%; OR 0.40, 95% CI 0.18–0.89). These findings support enhanced screening and preventive strategies in at-risk patients.

Natural selection is expected to maintain a stable 1:1 sex ratio in randomly mating populations. However, obligate parasites, especially nematodes with complex host-migratory life cycles, often show pronounced departures from this equilibrium. Ascaris suum, a globally distributed nematode with an XX/XO sex-determination system, exhibits an obvious female-biased sex ratio in adults, making it an ideal model to investigate when and how sex-ratio bias arises. Progress has been limited because, at present, no practicable method exists to identify worm sex at stages other than adulthood. Here, we aimed to establish a valid approach designed to be applicable, in principle, for precise sex identification and sex-ratio estimation across all stages of A. suum. Using a chromosome-level A. suum genome assembled in our laboratory (CNP0003380), we identified single-copy sequences on autosomes and the X chromosome and selected 3C (Chr3) as an autosomal marker and 5X (Chr5X) as an X-linked marker. We developed a qPCR assay that infers sex or sex ratio from the 3C/5X copy-number ratio, with theoretical values of 1 for XX females and 2 for XO males. Validation with 30 adult females and 30 adult males yielded 3C/5X ratios of 1.009 ± 0.042 and 1.995 ± 0.054, respectively, with no significant deviation from theoretical expectations (p > 0.05). The relative abundance of X-bearing to O-bearing sperm measured by qPCR was 0.980 ± 0.093, compared with 1.081 ± 0.163 by flow cytometry. Although the mean values differed significantly between the two methods (paired Students t-test, t = −2.886, d.f. = 29, p = 0.0073), the qPCR-based estimates showed lower variability than those obtained by flow cytometry. These results indicate that this qPCR assay provides an accurate tool for sex identification and quantification of the relative abundance of X-bearing to O-bearing sperm in A. suum.

The host-parasite relationship is affected by various biological, ecological, and anthropogenic factors. Some of them, such as host sex, are well studied. On the other hand, the effect of genetic differences, such as the presence of supernumerary or B chromosomes (Bs), has received little attention. We investigated the independent and interactive effects of host sex and B chromosome presence on intestinal nematode abundance in 294 yellow-necked mice (Apodemus flavicollis) from 18 localities in Serbia. Nine nematode species were identified. Because parasite numbers showed high inter-individual variability, we used a Monte Carlo randomisation method to test differences in mean abundance without assuming a specific statistical distribution. Host sex had a limited influence on infection patterns. In line with existing theoretical frameworks, a significant male-biased abundance was detected, but only for Aonchotheca annulosa, whereas no overall sex bias was found for total nematode burden. B chromosome carriers were found to have a significantly higher abundance of Syphacia frederici. A significant interaction between sex and Bs was detected for total intestinal nematodes and Syphacia stroma, with females carrying Bs harbouring the highest parasite loads. The results, indicating that Bs can shape helminth infrapopulation structure and that their effects may be sex-dependent, were discussed. The absence of consistent male-biased parasitism further suggests that sex effects are parasite-specific rather than universal. Our study highlights the importance of considering cryptic genomic variation in host–parasite research and demonstrates the value of Monte Carlo methods for analysing overdispersed helminth abundance data in wildlife hosts.

Echinostomes are a globally distributed group of digeneans with complex life cycles. In South America, many species are known only from definitive hosts, and in Argentina, most larval stages and adult records remain unlinked. Formal morphological descriptions and molecular data are essential for identifying larval stages; however, molecular reference sequences of larval digeneans remain scarce. We present an integrated morphological and molecular characterisation of echinostome cercariae from Biomphalaria aff. straminea collected between January 2017 and February 2018 in a rice field from Corrientes Province, Argentina, based on partial DNA sequences of the nuclear 28S rRNA (28S) gene and the mitochondrial marker nad1 gene. Eighty-three snails (2.12%) of the 3,913 sampled were infected with three echinostomatid morphotypes: Cercaria Echinostoma sp. 20 (1.63%); Cercaria Echinostomatidae gen. sp. 21 (0.25%); and Cercaria Drepanocephalus sp. (0.23%). Available Echinostomatidae sequences in GenBank were aligned with newly generated sequences from echinostomatid cercariae. Phylogenetic analyses showed that Echinostoma sp. 20 represents a distinct lineage that does not group with other Echinostoma sequences in GenBank; Echinostomatidae gen. sp. 21 does not cluster with Echinostoma and likely belongs to a genus related to Patagifer, although its position differs between the 28S and nad1 trees and it shows morphological differences; and Drepanocephalus sp. clusters with D. spathans from Mexico with low genetic divergence (<4.6%), although additional sequence data are needed to clarify species boundaries. This study provides the first molecular identification of Drepanocephalus and Echinostoma species in freshwater snails from Argentina, expanding the molecular dataset for Drepanocephalus in South America.

Anuran amphibians play essential ecological roles and are considered important bioindicators. This is especially true during the larval stage, when tadpoles exhibit high sensitivity to parasitic infections, including trematode metacercariae. These infections can profoundly affect the physiology and morphology of juvenile hosts, potentially compromising tissues involved in osmoregulation, locomotion, and development. We analysed naturally infected tadpoles, performing parasitological screening and histopathological evaluation. Through field collection, euthanasia, histological processing, and microscopic analysis of the tissues, our results revealed that the presence of metacercariae is directly associated with progressive tissue damage. In the kidneys, after the establishment of the parasite in a previously healthy renal tubule, we observed alterations ranging from mild changes, such as a slight reduction in glomerular density in individuals with low infection intensity, to severe damage in highly infected individuals. In the tail musculature, the metacercariae were encapsulated between muscle bundles, forming cysts delimited by fibrous capsules, accompanied by alterations in the organisation of muscle fibres, disruption of connective tissue, and the presence of inflammatory infiltrate. Capsules surrounding the parasites were composed of both host tissues and parasite-derived structures. Their formation was frequently associated with necrotic areas and functional impairment. These findings demonstrate that trematode infection exerts progressive effects on the structure and morphology of renal and muscular tissues in tadpoles, with the severity of tissue damage increasing according to parasite infection intensity. Such alterations may compromise host tissue integrity and represent an important pathological consequence of natural trematode infections during the larval stage.