Search Results (136)

Some groups of Diphyllobothriid tapeworms can cause foodborne or waterborne taeniasis, yet their systematics and evolution remain poorly understood. Based on mitochondrial genome data, this study reconstructed the phylogenetic trees of 11 cestode orders using maximum likelihood and Bayesian methods, clarified the valid species of Spirometra, traced the evolutionary history of four key ecological traits, and estimated the divergence times of major groups. Phylogenetic analyses supported Diphyllobothriidea and Bothriocephalidea as distinct clades, with Diphyllobothriidea forming a sister group to Haplobothriidea. In addition, three novel types of mitochondrial gene arrangements were identified in tapeworms, and variations in these arrangement types appear to correspond to changes in proglottid morphology. Species validation has shown that the available Spirometra mitogenomes represent only four valid species. Phylogenetic analysis identified two genetic lineages within S. mansoni, and a comparison of their representative sequences showed that the differences mainly lie in 12 PCGs, 7 tRNAs, 2 rRNAs, and 2 mNCRs. Ancestral character reconstruction suggested that tapeworms likely originated from freshwater fish hosts, with gradual adaptation to terrestrial hosts representing the main pathway of diversification, whereas transitions to marine environments were independent evolutionary events occurring in only a few groups. Molecular clock analyses indicated that tapeworm diversification began in the mid-to-late Oligocene, with episodic species radiations in different groups closely linked to host diversification and climatic changes. Notably, most groups within the family Diphyllobothriidae radiated during the Pleistocene, whereas Spirometra radiated during the Pliocene, coinciding with the origin of human-specialized cestodes. This study clarifies the phylogenetic position of diphyllobothriid tapeworms, infers the evolutionary patterns of ancestral traits across different tapeworm groups, and provides a theoretical basis for elucidating the origin and species diversity of tapeworms, as well as for assessing the transmission risk of pathogenic species. Full article

Habitat alteration and biological invasions are two main drivers of biodiversity loss at the global scale. Eutrophication and invasive fish greatly disturb freshwater native communities. This is of particular conservation concern in the Iberian Peninsula (Portugal and Spain), where fish fauna display a high level of endemism. For this eco-region, there is a dearth of information on the interactions among water quality, physical condition and parasites of invasive fishes. Consequently, the aim of this study was to assess the effect of nutrient enrichment on health status and parasitological traits in the invasive mosquitofish Gambusia holbrooki inhabiting an Iberian river. Water (n = 18 replicates, three per site) and fish (n = 400 individuals, 33–34 ind. per site and year) samples were collected in September 2024 and 2025 along the River Bullaque (central Spain). Sampling effort was standardised among sites, with the following parameters consistent: seine and pond nets were used, deployed by wading; 10:00 solar time; 1.5 h duration; personnel (the same seven trained researchers); and weather/environmental conditions; ensuring methodological consistency and data comparability. Laboratory procedures were carried out near the sampling sites to minimise both fish stress and distortions to parasite communities. Morphological and parasitological parameters were compared between mesotrophic and eutrophic reaches (six sampling sites, three per reach). Body condition and health assessment index* were greater under eutrophic conditions. Fluctuating asymmetry (a measure of developmental instability) was significantly higher for eye diameter in the mesotrophic reach. Parasite taxonomic composition differed between reaches, with more digeneans and cestodes in the mesotrophic sites, whereas ciliates and monogeneans were more abundant in mosquitofish from the eutrophic reach. Parasite prevalence, abundance and index of life-cycle complexity (heteroxenous species) were lower in the eutrophic reach. These results strongly suggest that eutrophication can facilitate mosquitofish invasiveness. This is reflected in a variety of morphological and parasitological traits, such as better body condition, health status, developmental stability, parasite resistance and tolerance. Overall, these parameters indicate that mosquitofish is taking advantage of anthropogenic impacts to improve their level of establishment and subsequent spread throughout Iberian fresh waters. Full article

The Barbary partridge (Alectoris barbara), an endemic game bird in Algeria, has not been systematically investigated for parasitic infections despite its ecological, economic, and conservation importance. This study provides the first eco-epidemiological and histopathological assessment of Capillaria contorta infection in birds from a semi-captive breeding center in Zeralda, Algeria. Between 2021 and 2024, 1085 pooled fecal samples and 138 postmortem examinations were analyzed using standard parasitological and histopathological methods. C. contorta showed an aviary-level overall prevalence of 32.94% and was involved in 42.02% of parasite-related mortalities, underscoring its marked pathological significance. Aviary-level prevalence varied significantly across seasons and years (p < 0.05), with higher levels recorded during environmentally favorable periods. Mixed infections with helminths, protozoa, cestodes, and ectoparasites were recorded for the first time in this host species at the aviary level, highlighting complex parasite interactions. Morphological characteristics were consistent with C. contorta. Gross examination revealed marked thickening of the esophagus and crop. Histologically, the adult nematodes were embedded within hyperplastic epithelium, with characteristic bipolar-plugged eggs and associated epithelial tunnels, accompanied by chronic inflammation and granulomatous reactions. These findings demonstrate the clinical relevance of C. contorta and emphasize the need for strengthened surveillance and control programs to reduce infection pressure and prevent potential spillover to wild populations. Full article

Helminth infections remain a major constraint to livestock productivity, particularly in regions where domestic animals and wildlife share grazing habitats. This study investigated the molecular diversity and transmission dynamics of helminth communities in sheep (Ovis aries) and saiga antelope (Saiga tatarica) in West Kazakhstan. A total of 35 animals (20 sheep and 15 saiga) were examined, and helminths were identified using polymerase chain reaction targeting the ITS1 region of ribosomal DNA for nematodes and the mitochondrial cox1 gene for cestodes. Of the 20 analyzed samples, 80% were successfully identified at the molecular level. Detected species included Haemonchus contortus, Trichuris ovis, Chabertia ovina, Moniezia expansa, and Avitellina centripunctata. Phylogenetic analysis revealed that Chabertia ovina isolates from both hosts clustered within a single monophyletic clade, indicating high genetic similarity and supporting potential cross-species transmission. Mitochondrial markers provided higher resolution for cestode differentiation, whereas ITS1 was effective for nematode identification. The predominance of Chabertia ovina in saiga suggests ecological adaptation and efficient transmission within wild populations. These findings highlight the epidemiological significance of shared grazing ecosystems and underscore the need for integrated parasite control strategies that consider both livestock and wildlife reservoirs. Full article

The Eurasian lynx (Lynx lynx) is an apex predator and an important sentinel for trophically transmitted helminths acquired via predation on wild ungulates. On 2 March 2022, an adult male lynx that was road-killed in the Apuseni Mountains (Surducel hunting ground, Bihor County) was collected, frozen for biosafety, and a necropsy was performed. Taeniid cestodes were detected, with a total intestinal burden of nine adult specimens. Genetic analyses confirmed Taenia lynciscapreoli, and the obtained sequences were deposited in GenBank (PV843597, PV855065, PV844409). Phylogenetic inference based on cox1 assigned the Romanian isolate within the European cluster, distinct from the Chinese isolate, while showing genetic proximity to Taenia sp. (MW846305) that have been reported from a lynx in China. This study represents the first molecular identification of T. lynciscapreoli in the Eurasian lynx in Romania and, to our knowledge, the first record from Southeastern Europe. Full article

This paper presents an analysis of helminth diversity in green frogs of the Pelophylax esculentus complex from twelve provinces of the Middle Volga region (European Russia). The study relies on the occurrence dataset recently published in GBIF in the form of a Darwin Core archive. The database contains current information on helminth occurrences in these anurans, comprising records from our long-term helminthological survey conducted in 1997–2025. Our database includes 13,634 helminth occurrence records for three Pelophylax species residing in the Middle Volga region. Each helminth occurrence record is linked to georeferenced data. A total of 43 parasite species are documented in the dataset, including 29 species of trematodes, one cestode, 11 nematodes, and two acanthocephalans. The greatest helminth diversity was recorded in Pelophylax ridibundus (42 species), which is the most widespread and abundant amphibian species in European Russia. The helminth fauna is less diverse in Pelophylax lessonae (32 species) and their hybrid, Pelophylax esculentus (25). Most helminth species found in green frogs within the studied area belong to the Palearctic faunal complex (29 species). Five helminth species each have European and Holarctic distributions, while four species are cosmopolitan. Of the 43 species of helminths found, three (Alaria alata, Spirometra erinacei, Ascarops strongylina) are of medical and veterinary importance as causative agents of parasitic zoonoses, posing a threat to domestic animals and humans. Full article

Anostomidae is one of the most diverse families within the order Characiformes and is widely distributed across the river basins of the Neotropical region. Anostomids are known to host a rich diversity of metazoan parasites, including ectoparasites, such as monopisthocotylans, and endoparasites, such as nematodes, cestodes, and digeneans. The present study aims to develop an inventory of metazoan parasites recorded in fish of the Anostomidae family. A bibliographic review of metazoan parasite species in anostomids was conducted, using searches in different databases. This bibliographic review was complemented with information from books and book chapters on ictioparasitology. The data were compiled until January 2025. Based on the review, 191 taxa (126 are described at the species level and 65 were identified only to the genus level or higher taxonomic categories) of metazoan parasites associated with anostomid fishes were found. Monopisthocotyla and Nematoda were the taxonomic groups with the most parasitic associations at the species level, with 31 and 30 species, respectively. This study presents a comprehensive and updated inventory of metazoan parasites associated with fish from the family Anostomidae, covering over 170 years of research (1850–2025). This survey highlights the importance of anostomids as hosts for a rich parasitic fauna. Full article

Scavenger Receptors (SRs) comprise a structurally diverse group of pattern recognition receptors (PRRs) involved in sensing non-self (microbial-associated molecular patterns) or altered-self ligands. CD5 and CD6 are class I SRs (SR-I) preferentially expressed by lymphoid cells and characterized by the presence of several tandem scavenger receptor cysteine-rich (SRCR) domain repeats. Both receptors interact with diverse microbial structures, including tegumental antigens from Echinococcus granulosus sensu lato (s.l.), the cestode parasite responsible for cystic echinococcosis (CE). This is notable as very few PRRs are currently known to detect parasitic helminths and because the infusion of recombinant soluble CD5 and CD6 proteins has shown prophylactic effects in murine secondary CE. Herein, the role of CD5 and CD6 in early immune responses to E. granulosus s.l. tegumental antigens (PSEx) was analyzed using CD5 (Cd5^−/−) and CD6 (Cd6^−/−)-deficient mice. Peritoneal B cells and macrophages from wild-type mice displayed specific and dose-dependent PSEx binding, which was impaired in those from Cd5^−/− and Cd6^−/− mice, supporting direct and/or indirect roles in parasite recognition. Additionally, in vivo exposure of peritoneal exudate cells (PECs) from Cd5^−/− and Cd6^−/− mice to PSEx showed altered activation profiles, including changes in CD80/CD86 expression, impaired early production of natural polyreactive antibodies, and cytokine shift from a Th1/Th17 to a Th2 profile. These findings strongly support the involvement of CD5 and CD6 receptors in the early immune recognition of E. granulosus s.l. antigens by PECs and influence immune responses critical for host resistance, highlighting their relevance in host–parasite interactions. Full article

Parasitism affects nearly half of all animal species and strongly influences ecosystem dynamics. Despite their sentinel value, parasitic infections in cetaceans remain understudied. This study assessed the diversity, prevalence, and burden of gastrointestinal and pulmonary parasites in seventy-five stranded cetaceans from six species along the central and northern Portuguese coastline. Coprological methods included Mini-FLOTAC^®, Willis-flotation, natural sedimentation, modified Ziehl–Neelsen staining, direct immunofluorescence, and adapted spontaneous sedimentation. Overall, 61.3% of samples tested positive for at least one parasitic taxon, with 22.7% showing coinfections. Anisakidae and Ascaridida were the most prevalent (36%), followed by Pseudaliidae larvae (5.3%), unidentified trematode eggs (8.0%), Odhneriella spp. (5.3%), Nasitrema spp. (2.7%), Zalophotrema spp. (2.7%), and Synthesium spp. (1.3%). Nematode eggs exhibited the highest mean burden, with anisakids reaching 4862 eggs per gram of feces (EPG), whereas trematodes showed a markedly lower burden, exemplified by Zalophotrema spp. with 90 EPG. All samples assessed were negative for Cryptosporidium spp. and Giardia spp. Unidentified ovoid structures were present in 76% of samples. Macroscopic sedimentation revealed anisakid larvae, one cestode, over fifty Ogmogaster antarctica specimens, and six marine arthropods. These findings provide baseline data for cetacean parasitology and support future integrative research for conservation and ecosystem health. Full article

In this study, the ultrastructural characteristics of the mature spermatozoon of the cestode Gerbillitaenia psammomi, a parasite of the fat sand rat (Psammomys obesus) in the south of Tunisia, were examined by means of transmission electron microscopy. The spermatozoon is of Levron et al.’s type VI. This type of sperm cell is mainly characterized by the presence of a single axoneme of the 9 + ‘1’ pattern typical of the trepaxonematan Platyhelminthes, crest-like bodies, a periaxonemal sheath, twisted cortical microtubules, and a spiraled nucleus. The spermatozoon of G. psammomi possesses two crest-like bodies of different length. The results obtained in the present study suggest certain similarities with the remaining analyzed catenotaeniids; namely, Catenotaenia pusilla, Skrjabinotaenia (Meggittina) gerbilli, and Spasskijela lobata. The results are compared and discussed according to several characteristics found in the catenotaeniids and other studied cestodes, particularly those of the order Cyclophyllidea. Full article

The golden jackal (Canis aureus) is a highly adaptable wild carnivore whose expanding range in Kazakhstan increases contact with livestock, wildlife, and human-modified environments. Despite its potential epidemiological importance, data on helminth infections in jackals from southern Kazakhstan remain limited. In this study, 13 golden jackals collected from four regions of southern Kazakhstan were examined by necropsy of internal organs and coprological analysis. Helminths were identified using morphological methods and molecular genetic analysis of mitochondrial (cox1) and ribosomal (NC13/NC2) markers. Five helminth species were detected, including the nematodes Toxascaris leonina and Toxocara canis, and the cestodes Taenia multiceps, Taenia krabbei, and Mesocestoides sp. Molecular phylogenetic analyses confirmed species-level identification of nematodes and cestodes and showed clear clustering with reference sequences. Overall, 46% of examined jackals were infected with at least one helminth species. The presence of taeniid cestodes and zoonotic nematodes highlights the role of golden jackals as definitive hosts in parasite transmission cycles involving wildlife, livestock, and humans. These findings provide new molecular and epizootological data on helminths of golden jackals in southern Kazakhstan and contribute to understanding their epidemiological significance. Full article

Emerging evidence suggests that certain cestodes, including Taenia solium, may actively modulate the host’s hormonal and immune environment to facilitate their survival. This study aimed to determine whether patients diagnosed with neurocysticercosis (NCC) exhibit immunoendocrine alterations associated with infection. A clinical study was conducted in Honduras, enrolling 11 adult NCC patients (9 female, 2 male) and 11 age- and sex-matched healthy controls. Serum concentrations of seven hormones and two cytokines were evaluated. Compared to controls, NCC patients showed significantly elevated levels of 17β-Estradiol (E2), Progesterone (P4), Androstenedione (A4), Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), Interleukin-6 (IL-6), and Interleukin-10 (IL-10). Conversely, Free testosterone (FT) and Dihydrotestosterone (DHT) levels were significantly reduced. These findings support the hypothesis that T. solium may manipulate host immunoendocrine pathways to promote its establishment and persistence within the central nervous system. Full article

Taenia crassiceps is a cestode capable of causing severe and atypical cysticercosis in accidental intermediate hosts, including domestic dogs. Here we report a fatal disseminated T. crassiceps infection (cystiscercosis) in a 4-year-old castrated male German Shepherd from Poland that had been undergoing long-term prednisone therapy for Addison’s disease. The dog developed multiple soft subcutaneous nodules containing numerous asexually proliferating cysticerci. Necropsy revealed extensive dissemination of larvae throughout the subcutis and the thoracic and abdominal cavities, accompanied by serosanguineous effusions, necrosis, and chronic inflammatory lesions. Histological examination demonstrated cestode larvae with a scolex bearing two rows of hooks, consistent with T. crassiceps. Immunosuppression and endocrine alterations, including chronic glucocorticoid treatment and low levels of testosterone, likely promoted rapid asexual proliferation of larvae. A literature review shows that although dogs are definitive hosts of T. crassiceps, immunosuppressed individuals may also serve as accidental intermediate hosts. Early cytological evaluation of subcutaneous nodules may facilitate faster diagnosis and treatment decisions. Given the zoonotic potential of T. crassiceps and the increasing number of European cases, this parasitic infection should be considered in the differential diagnosis of subcutaneous nodules in immunosuppressed dogs. The presented case underscores its epidemiological relevance within the One Health framework. Full article

The wolf (Canis lupus) is an apex predator with high mobility and trophic plasticity, serving as a valuable indicator of helminth transmission at the wildlife–livestock interface. Given the ecological overlap between wolves and both wild and domestic ungulates in Romania, we aimed to identify and molecularly characterize cestodes from wolves’ small intestines. Between November 2022 and June 2025, small intestines from nine wolves were collected across four Romanian counties, frozen, and examined using classical parasitology (macroscopic and microscopic) and molecular methods (PCR amplification and Sanger sequencing of mitochondrial cox1, nad1, and 12S rRNA fragments). Taeniids were detected in three (33.33%) out of nine tested individuals. Genetic analyses confirmed the presence of Taenia krabbei and Taenia hydatigena—species not previously reported in wolves from Romania. This study provides the first molecular evidence of T. krabbei and T. hydatigena in wolves from Romania, and likely Eastern Europe, indicating active transmission and underscoring the need for broader surveillance of hosts to clarify their ecology and regional dynamics within a One Health context. Full article

The high incidence of anthropogenic impacts in the Mediterranean basin raises concerns on the health and quality of commercial fish species. This study aims to evaluate the health status of the European hake, Merluccius merluccius, from three areas of the Catalan coast (NW Mediterranean Sea) with different anthropogenic impacts (i.e., chemical pollution, litter, …) and assess if hake could serve as a sentinel species. We measured biomarkers of chemical exposure including B-esterases, antioxidant enzymes (GST, GR, GPx, CAT), biotransformation markers (EROD), lipid peroxidation, and macro-parasite assemblages. Hake showed, generally, a good health status across all areas with homogeneous patterns for most parameters. Tissue-specific differences included elevated gonadal cholinesterases and higher brain and hepatic carboxylesterase activities in the south, and increased hepatic EROD but lower lipid peroxidation in the central Barcelona area. Parasite assemblages were dominated by Digenea, Cestoda, and Nematoda, with higher cestode prevalence in both central and south zones. In summary, despite a greater prevalence of environmental pollution in the central region, there was a homogeneous pattern in hake health indicators throughout the three studied fishing zones. These results establish a baseline for hake health in Mediterranean waters and suggest that the species’ high mobility and wide depth range may limit its utility to detect local-scale pollution impacts, though it may serve as a regional-scale bioindicator. Full article