Parasitology Research最新文献

Global changes in the marine Arctic ecosystem affecting the demography of fish and seal populations may also alter their anisakid parasite populations size, potentially leading to genetic erosion in gene pools. Contracaecum osculatum sp. B, an Arctic member of the C. osculatum (s.l.) species complex, parasitizes Arctic and sub-Arctic seals and fish. This study aimed to compare parasite genetic diversity across the Nordic Seas over time, using historical specimens (1985-1986) and contemporary ones (2021-2022) obtained from seals and fish of the same regions. Parasites were first identified by sequence analysis of mtDNA cox2 and ITS rDNA, then genotyped at seven SSRs nuclear DNA loci, developed in the present study. The population genetic structure of C. osculatum sp. B revealed the existence of two parasite subpopulations, a pattern that appears to be mostly influenced by the population structure of the seal hosts in the area. High genetic polymorphism was observed in the parasite species, at both nuclear and mitochondrial level. In the contemporary parasite population gene pool, some rare haplotypes in mtDNA cox2 and rare alleles at SSRs-DNA loci appeared to be lost in comparison to the historical population; while, novel unique alleles and haplotypes simultaneously emerged. Overall, these findings would suggest the occurrence of an initial decline in parasite population size, followed by a period of demographic stability, and a population increase in recent years. Similar demographic patterns have been documented in the host populations over the same time scale. Genetic polymorphisms in anisakids across temporal scales may help unravel and monitor trophic-web dynamics in the Arctic marine ecosystem under global change.

Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus sensu lato (s.l.), remains a significant zoonotic parasitic infection worldwide. This study provides a preliminary investigation of the nuclear Hsp90 gene diversity within the E. granulosus s.l. complex to evaluate its potential use for species identification. Forty-nine DNA samples of the G1 genotype from human and animal CE cysts, two G3 genotype samples, one of Echinococcus ortleppi, four of Echinococcus canadensis (G7), and four samples of other Taenia species (Echinococcus multilocularis, Taenia hydatigena, Taenia pisiformis, and Taenia ovis) were analyzed. Four primer pairs were designed to amplify the Hsp90 gene, followed by PCR amplification, DNA sequencing, and phylogenetic analysis. Successful amplification and sequencing of nearly the entire Hsp90 gene revealed a single nucleotide polymorphism (SNP) at position 222 conserved across all genotypes. Notably, significant genetic variations were observed between E. ortleppi (G5 genotype) and E. canadensis (G7 genotype) compared to E. granulosus sensu stricto (G1 and G3 genotypes). Phylogenetic analysis confirmed clustering consistent with established taxonomic relationships, with G1 and G3 forming a cluster, and G5 and G7 forming a distinct group. The findings suggest that the nuclear Hsp90 gene could be used as an additional marker for species-level differentiation within the E. granulosus s.l. complex.

Anisakiasis is a foodborne zoonosis caused by ingesting raw seafood containing anisakid larvae. Its global incidence has increased with rising seafood consumption, highlighting the need for effective prevention methods. While freezing at -20 °C for 24 h is a standard preventive measure, it compromises seafood quality. Pulsed power (PP) technology, delivering high-voltage microsecond pulses, has emerged as a promising non-thermal alternative. Here, we evaluated PP inactivation efficacy using agar penetration and rabbit infection tests. Larvae treated with 10 pulses of 13 kV for 10 µs failed to penetrate agar (0/40), whereas 35/40 untreated larvae penetrated agar (p = 0.0202). In the rabbit model (four animals/group), PP-treated larvae caused no gastric wall penetration, and only three nonviable larvae were observed in the gastric lumen. Conversely, untreated larvae invaded the gastric mucosa (mean: ~ 21/50), lumen (~ 7.8/50), and peritoneal cavity (~ 2.3/50). Gastric wall penetration was significantly lower in the PP group than in the untreated group (p = 0.0211), with a relative risk of 0.006. These results objectively demonstrate complete inactivation of anisakid larvae after PP treatment. PP represents a promising alternative to freezing and holds potential for broader application, provided that compact devices are developed for practical use in seafood processing.

Bat ectoparasites are an integral part of the wildlife and of host-parasite interactions in the Baja California Peninsula (BCP), Mexico, but the study of these ectoparasites is scarce in this area. In this study the ectoparasite faunal composition of the bat families Phyllostomidae and Vespertilionidae was determined and the first ectoparasitic checklist from BCP was developed. Thirteen bat species (Phyllostomidae, N = 1, Vespertilionidae, N = 12) from the northern and central region of the BCP were analysed. The checklist is presented in two tables, a parasite-host list and a host-parasite list. Twenty-three ectoparasite taxa were recorded, belonging to the five orders Ixodida (Argasidae), Mesostigmata (Macronyssidae, Spinturnicidae), Trombidiformes (Trombiculidae, Leeuwenhoekiidae, Myobiidae), Diptera (Nycteribiidae, Streblidae), and Hemiptera (Cimicidae), from nine bat species: Leptonycteris yerbabuenae, Antrozous pallidus, Corynorhinus townsendii, Eptesicus fuscus, Myotis californicus, M. ciliolabrum, M. evotis, M. vivesi and M. volans. Six taxa of Acari are new records for BCP and Mexico, i.e., Albeckia albecki, Acanthophthirius caudatus eptesicus, Acanthophthirius sp. 1, Acanthophthirius sp. 2, Trombiculidae Gen. sp. 1 and Steatonyssus occidentalis. Ectoparasites of Vespertilionidae likely share Nearctic affinities in relation with their hosts' distribution, as ectoparasites of Phyllostomidae do with Neotropical affinities. This study is pioneer in the construction of baseline data of bat ectoparasite diversity in the BCP; due to lack of information, it is necessary to continue the studies of ectoparasites for bat species of the families Emballonuridae, Molossidae, Mormoopidae, and Natalidae.

Among the Ixodid ticks, Hyalomma anatolicum is a well-known vector that transmits various pathogens to terrestrial and semi-terrestrial vertebrates including humans, and its population differ in ecology and vector competence. Expansion of this tick to new areas changes the genetic structure, and lead to affect the vector-pathogen interaction and disease outcomes. The present study was designed to infer the haplotype diversity, demographic dynamics, gene flow and genetic differentiation, and phylogeny of H. anatolicum from different countries based on the cytochrome oxidase I (COI) and 16S rDNA sequences. A total of 320 ticks were collected from cattle, buffaloes, and sheep in five districts of Khyber Pakhtunkhwa, Pakistan, morphologically identified as H. anatolicum, and subjected to genetic analysis. A total 85 and 138 sequences for COI and 16S rDNA, including 11 and 2 sequences generated in this study, respectively, were analyzed to assess haplotype network, population structure and divergence, demographic changes, and phylogenetic analysis. Analysis based on COI sequences yielded 29 haplotypes in which haplotype 1 and 15 were the predominant consisting of 35 and 20 sequences, respectively, from Pakistan, India, China, Bangladesh, Iraq, Saudi Arabia, Kazakhstan and Egypt. The 16S rRNA yielded 30 haplotypes in which haplotype 1 was predominant consisting of total 86 sequences from Pakistan, India, China, United Arab Emirates, Tajikistan, Kazakhstan, Turkey, Egypt, and Iraq. Complete haplotype network based on COI and 16S rRNA confirmed stellate structure, together with high haplotype diversity (COI 0.77899, 16S rRNA 0.60774) and low nucleotide diversity (COI 0.00445, 16S rRNA 0.00431), which support recent population expansion. Similarly, neutrality indices for the whole dataset, Tajima's D (COI - 2.36363^**, 16S rRNA - 2.54127^***), Fu and Li's D (COI - 5.72992, 16S rRNA - 6.31313^*), and Fu and Li's F (COI - 5.04435^*, 16S rRNA - 5.56085^*) were negative, indicating deviation from neutrality and recent population dispersal. In the phylogenetic tree based on the COI and 16S rDNA sequences, with exception of one sequence for a single haplotypes, which appeared independently, there is a single main clade that includes the largest number of sequences for all other haplotype. Based on COI and 16S rDNA sequences, the present study provided first detail information about the population genetics and haplotype networks of H. anatolicum.

Plasmodium vivax is a malaria parasite with a broad geographic distribution worldwide. The unique biological characteristics of P. vivax, such as early gametocytogenesis and its latent hypnozoite stage, make it more difficult to control compared to P. falciparum. Malaria remains a significant global health concern, particularly in regions with limited diagnostic infrastructure. This study aims to develop a computer-assisted method for characterizing and classifying malaria parasites using a machine learning approach based on light microscopic images of peripheral blood smears. One of the major challenges in malaria diagnostics is the inadequacy of current detection methods. To address this, the study introduces a convolutional neural network (CNN)-based pipeline for the automated detection and staging of malaria infections from Giemsa-stained blood smear images. The dataset used in this study was annotated into four classes: Ring Form, Trophozoite, Schizont, and Uninfected Red Blood Cells (RBCs), encompassing diverse staining qualities and morphological variations. The dataset was divided into training (70%), validation (15%), and testing (15%) subsets. The CNN achieved an overall classification accuracy of 92.4%, with precision, recall, and F1-scores exceeding 0.90 across all classes. Statistical metrics, including mean accuracy (92.4% ± 2.1%), precision (93.1% ± 1.8%), and recall (92.8% ± 1.9%), demonstrated the robustness of the model. Class-specific analysis revealed that the Schizont stage achieved the highest classification accuracy (94.7%), while the Ring Form stage showed slightly lower performance (91.2%), likely due to inherent morphological overlaps with early Trophozoite forms. Visualizations, including confusion matrices and class probability distribution overlays, provided detailed insights into the model's decision-making processes. The pipeline was further evaluated using cross-validation techniques, showing high reliability across various dataset splits. This approach offers scalability and adaptability, with the potential for deployment in real-world diagnostic workflows, particularly in resource-constrained settings.

Leishmaniasis is a vector-borne disease endemic in more than 99 countries and manifests primarily as cutaneous, mucocutaneous, or visceral forms. This study aimed to assess the impact of Leishmania RNA virus 2 (LRV2) on immune responses and disease pathology in mice infected with Leishmania tropica. BALB/c mice were inoculated subcutaneously in the right hind footpad with L. tropica either lacking or carrying LRV2 (LRV2- and LRV2 + groups, respectively) and monitored for 24 weeks. Footpad and liver tissues were collected post-sacrifice, and parasite presence was determined using microscopy, culture, and molecular methods. Biomarkers of inflammation (IL-6, TNF-α, and TGF-β1), oxidative stress (iNOS and eNOS), and apoptosis (Caspase 3) were analyzed by immunohistochemistry and qPCR. Leukocyte infiltration was observed in footpad lesions of both LRV2- and LRV2 + groups; however, lesion sizes did not differ significantly between them. In footpad tissues, TNF-α, TGF-β1, eNOS, and Caspase 3 expression levels were significantly higher in both experimental groups compared to controls. In liver tissues, IL-6 and eNOS expression was significantly elevated in both experimental groups relative to controls, while TNF-α expression was notably higher in the LRV2 + group. Furthermore, both footpad and liver tissues from LRV2 + mice showed increased eNOS and iNOS expression compared to LRV2- mice. Overall, these findings indicate that the presence of LRV2 does not significantly influence inflammatory cytokine production or apoptosis in footpad and liver tissues, but it markedly enhances oxidative stress in both.

Clestobothrium crassiceps (Rudolphi, 1819) Lühe, 1899 is the type species of the genus Clestobothrium Lühe, 1899, originally described from Merluccius merluccius (Linnaeus, 1758) in the Mediterranean Sea. Despite its apparently wide host and geographic ranges, this species remains poorly understood due to the lack of detailed morphological, genetic and epidemiological data. In the present study, newly collected materials of C. crassiceps from M. merluccius off Barcelona, Spain (NW Mediterranean) were used to provide the first complete description from its type-host and locality. An integrative approach was applied, combining traditional morphological techniques with confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), molecular, histological and epidemiological data. Confocal microscopy revealed key diagnostic features of the female reproductive system (i.e. vagina, Mehli's gland, uterus tube), while SEM analysis showed, for the first time, different distribution patterns of microtriches along the scolex and strobila. Histological observations showed the attachment mode of the scolex to intestinal folds, causing mild epithelial alterations such as attenuation of the intestinal epithelium. Prevalence and intensity of infestation with C. crassiceps were higher in larger fish, suggesting a role for dietary shifts and potential paratenic hosts in transmission. Phylogenetic analysis based on newly generated 28S and cox1 sequences confirmed the monophyly of the genus Clestobothrium and highlighted an intraspecific variation comparable to the genetic divergence observed between congeners C. splendidum and C. cristinae. Based on these results, a morphological reexamination of paratypes of both species was conducted, proposing C. cristinae as a junior synonym of C. splendidum.

We evaluated the effects of climatic factors, host and parasite species richness, and their phylogenetic and functional diversity on the nestedness and modularity of mammal-flea interaction networks from four biogeographic realms. We also tested for the associations between pure structural network dissimilarity (i.e., dissimilarity between host-sharing-by-fleas networks, Dh, or dissimilarity between flea-sharing-by-hosts networks, Df) and environmental dissimilarity, and host and flea compositional, phylogenetic, and functional dissimilarities. We asked whether (a) the relative effects of these factors differ between biogeographic realms and (b) the network structure is more strongly driven by environmental, geographic, host-associated, or flea-associated factors. The climatic drivers of nestedness and modularity differed between realms. The networks in different realms responded to different factors, with the directions of some of these effects being opposite. Among interactor-associated factors, host species richness was most often detected as an important driver of nestedness, whereas flea species richness mainly affected modularity. Dh was mostly explained by host-associated and, to a lesser extent, flea-associated dissimilarity. No effect of host-associated dissimilarity on Df was detected, but it was linked with flea-associated dissimilarity in two of the four realms. Environmental dissimilarity weakly affected Dh and did not affect Df. We conclude that between-realm differences in the drivers of network structure resulted from an interplay of ecological and historical factors, whereas between-interactor differences in their effects on the network structure arose due to the asymmetry in host-flea relationships.