Parasite最新文献

Parasites are known for their ability to induce a variety of changes in their respective hosts, including morphological characteristics and trophic interactions. For many host-parasite relationships, however, these aspects are yet to be explored. We assessed the occurrence of acanthocephalans and microsporidians in a population of the isopod Asellus aquaticus from a stream in western Germany over several months. We aimed to contrast the trophic positions of Acanthocephala-infected, Microsporidia-infected and uninfected isopods by assessing the stable isotope ratios for nitrogen (δ¹⁵N) and carbon (δ¹³C). We found acanthocephalans of the genus Acanthocephalus as well as five different microsporidian species, three of which are novel isolates. Prevalences were generally low among the 538 tested isopods (1.3% in September to 4.0% in January for acanthocephalans, and 0.7% in January to 12.3% in November for microsporidians), with a strong peak of microsporidian infections in November. The stable isotope analysis revealed temporal shifts in both δ¹³C and δ¹⁵N values, probably corresponding to dietary changes. Isopods infected with the microsporidian isolate EFB02 were enriched in ¹⁵N compared to uninfected ones, suggesting possible infection-associated physiological or metabolic changes. Acanthocephalan-infected isopods resembled uninfected ones in the two autumn samplings, but showed elevated δ¹⁵N values in September and January. This pattern may reflect active development of cystacanths in September and January, possibly linked to higher nutrient demands. Our findings emphasize the ecological importance of parasite infections in freshwater detritivores and underscore the need to consider the environmental and temporal context in host-parasite trophic studies.

Differentiating between two diphyllobothriid tapeworms Dibothriocephalus dendriticus and Dibothriocephalus ditremus is complicated due to their morphological plasticity, intraspecific variability and a wide range of common hosts. The aim of this study was to develop a species-specific PCR-based method for single-step discrimination between D. dendriticus and D. ditremus. Intraspecific variation and interspecific differences were analysed in subunits/spacers of nuclear rRNA genes and protein-coding genes of mitochondrial DNA. In addition, the specificity of primers designed for the amplification of microsatellite loci in D. dendriticus was tested on D. ditremus DNA. Due to high identity within the rRNA gene in these species, no suitable DNA regions could be identified for the design of the species-specific primers. A higher level of interspecific differences was detected in the mitochondrial cox1 and cob genes, in which regions containing species-specific mutations were chosen for the design of D. dendriticus- and D. ditremus-specific primers. However, their specificity was not confirmed, as the D. dendriticus-specific primers also annealed to D. ditremus DNA and vice versa. Of the 15 primer pairs designed for the amplification of microsatellite loci in D. dendriticus, 13 primer pairs also annealed to D. ditremus DNA. Only two primer pairs, which amplify the Dd_8 and Dd_33 loci have been proven to be D. dendriticus-specific. The effectiveness and high reproducibility of the Dd_8 primers were validated on ~3,500 D. dendriticus and D. ditremus plerocercoids from Iceland and Norway. These primers are recommended for future molecular differentiation between both Dibothriocephalus species.

Indoleamine 2, 3-dioxygenase (IDO) is a potent immunoenzyme found in dendritic cells (DCs). Research has demonstrated that Trichinella spiralis induces IDO expression in the host immune response through its excretory-secretory (ES) antigens. However, the role of IDO in the immune response to T. spiralis remains unclear. To examine the effects of T. spiralis ES antigens on IDO expression in DCs in vitro, assessments were conducted using qRT-PCR, Western blotting (WB), flow cytometry, and siRNA transfer. The findings indicated that ES antigen stimulation upregulated IDO expression in DCs in vitro. Furthermore, ES antigen significantly enhanced the expression of the proinflammatory cytokines TNF-α and IFN-γ, along with the anti-inflammatory cytokine IL-10, downstream of IDO in DCs. Flow cytometry analysis confirmed that surface molecules CD40, MHC-II, CD80, and CD86 on DCs were upregulated following stimulation with ES antigen and lipopolysaccharide (LPS). Compared to the ES antigen alone, siRNA620 effectively inhibited IDO levels, demonstrating a statistically significant reduction. Continuous stimulation of DCs by ES antigens may lead to immune tolerance through the activation of IDO-mediated inflammation-associated factors. These results suggest that IDO expression in DCs plays a crucial role in T. spiralis infection.

A novel myxosporean species was identified. The species formed spherical to ellipsoidal pseudocysts within the alimentary tract wall of a yellowfin seabream Acanthopagrus latus fished in the East China Sea. Histological examination confirmed that pseudocysts were localized within the submucosal layer of the stomach wall. Round to ellipsoidal myxospores exhibited two posterior caudal appendages, consistent with the morphological characteristics of the genus Henneguya. The myxospore body measured 9.6 ± 0.5 (8.6-10.6) μm in length, 7.3 ± 0.4 (6.8-7.9) μm in width, and 6.0 ± 0.2 (5.5-6.4) μm in thickness. Two equal pyriform polar capsules were observed, measuring 3.5 ± 0.3 (2.9-4.4) μm × 1.9 ± 0.2 (1.4-2.2) μm. Pairwise comparison referring to small subunit ribosomal DNA sequence revealed a highest identity of 94.19% with Henneguya yokoyamai Li et al., 2012, supporting the classification of the specimens as a new species, Henneguya cystigena n. sp. Phylogenetic analyses demonstrated intermixed groupings of myxobolid species, highlighting persistent discrepancies between traditional morphological taxonomy and increasingly refined molecular phylogeny. To the best of our knowledge, this study represents the first description of a Henneguya species parasitizing a marine fish in the East China Sea near mainland China.

Blastocystis sp. is a zoonotic intestinal protozoan that is ubiquitous globally, residing in the gastrointestinal tracts of both humans and various animals. In the present study, a PCR-sequencing tool based on the SSU rRNA gene was employed to investigate the prevalence and subtypes of Blastocystis spp. in 204 fresh fecal samples collected from 20 captive wildlife species from a bird park in Henan Province, Central China. Overall, Blastocystis was present in 13.73% (28 out of 204) of the samples and 25% (5 out of 20) of the species. A total of four zoonotic subtypes of Blastocystis sp. were found: ST1, ST3, ST5, and ST27, with the latter being the most prevalent, accounting for 35.71% (10 out of 28) of the 5 species positive for Blastocystis sp. To the best of our knowledge, this is the first report of Blastocystis ST27 in birds in China, namely bar-headed goose (Anser indicus) and peafowl (Pavo muticus). The data suggest that captive wildlife, particularly those in bird parks, may frequently be infected with this zoonotic pathogen. Consequently, these animals may serve as potential reservoirs for zoonotic infections in humans.

Leishmaniases are vector-borne parasitic diseases that pose a threat to over 1 billion people worldwide. The parasites target cells of the reticulohistiocytic system, such as macrophages, where they replicate. The disease manifests in various forms, ranging from localized cutaneous leishmaniasis to life-threatening visceral forms, which are fatal in 95% of cases without treatment. Current treatments rely on the invasive administration of toxic and expensive drugs that are increasingly encountering resistance. Therefore, finding alternative treatments for this disease is imperative. This literature review focuses on recent advancements in alternative treatments and aims to present the various strategies designed to address current limitations, including cost, toxicity, off-target effects, administration routes, and the emergence of drug resistance. Starting with an overview of the existing approved treatments and their specific limitations, we categorize treatment development strategies into five key sections: (i) combination therapies using existing approved treatments to enhance efficacy and reduce resistance; (ii) nanoparticle formulations, which enable targeted delivery to infected organs and improved therapeutic efficiency; (iii) drug repositioning, a strategy that has already contributed to the approval of over half of current therapeutic compounds; (iv) immunomodulation, used in conjunction with standard chemotherapies to enhance treatment efficacy and lower relapse rates; and (v) ethnobotanicals, which have demonstrated promising in vitro results by combining low toxicity, immunomodulatory properties, and potent anti-parasitic effects. In summary, this review outlines current strategies in treatment development, emphasizing their advantages over conventional therapies while acknowledging their limitations.

A new species of the genus Cardiodectes Wilson, 1917 (Siphonostomatoida: Pennellidae), Cardiodectes tofaili n. sp., is described based on 13 adult females from ten specimens of the endemic lightfish Vinciguerria mabahiss (Stomiiformes: Phosichthyidae). These hosts were inadvertently captured by a remotely operated vehicle at depths of 454-645 m in the pelagic waters of the Saudi Arabian Red Sea. The new species is placed under the "rubosus" group, characterized by possession of a trunk without a discrete abdomen. It is distinguished from its 12 congeners within this group by having a short neck region with a distinct fourth pedigerous somite, and a trunk that is ca. 5 times longer than wide. Phylogenetic analysis based on concatenated 18S + 28S rDNA sequences supports the distinctiveness of the new species. This species is endemic to the Red Sea, representing the first recorded mesoparasite from the mesopelagic environment of the region. This discovery highlights the unique biodiversity of the Red Sea and underscores the importance of exploring mesopelagic ecosystems.

Background: To correlate imaging features of alveolar echinococcosis (AE) with the antibodies to recombinant Em18 (rEm18AB) at diagnosis and evaluate initial imaging features associated with serologic response, this retrospective study used data from the prospective multicenter EchinoVISTA study (NCT02876146). Imaging and serology were performed at diagnosis and during follow-up. Univariate and multivariate analyses were used to evaluate imaging features associated with the rEm18AB index. Follow-up analyses evaluated the imaging features associated with serologic response (defined as a 50% reduction in the baseline value within 2 years) in non-operated patients treated with albendazole alone.

Results: From June 2012 to July 2016, 45 patients were included, with 8/45 (18%) having an rEm18AB index < 1. Maximum lesion size (76 mm [IQR = 57-93] vs. 36 mm [IQR = 26-51], p = 0.006), microcyst percentage (70% [IQR = 3-8] vs. 20% [IQR = 0.5-3.5], p = 0.004), and maximum standardized uptake value (SUV) on fluorodeoxyglucose positron emission tomography (5.1 [IQR = 4.4-6.2] vs. 2.6 [IQR = 2.4-3.9], p = 0.001) were associated with an rEm18AB index > 1. In patients treated with albendazole, serologic responders at 2 years had smaller lesions (5.3 [IQR = 3.8-72] vs. 3.5 [IQR = 2.7-3.7], p = 0.010) with less pedicle involvement, and lower initial rEm18AB index (2.98 ± 1.63 vs. 7.81 ± 3.95, p = 0.011).

Conclusion: Maximum lesion size, percentage of microcysts within the lesion, and maximum lesion SUV are significant imaging features of AE correlated with the rEm18AB index. Serologic response at 2 years occurs primarily in patients with small lesions and a low rEm18AB index.

Acanthamoeba spp. are free-living amoebae found in various water sources, including domestic tap water. These amoebae are known to cause Acanthamoeba keratitis, a severe corneal infection that can lead to vision loss. Although Acanthamoeba keratitis is commonly associated with water exposure, the environmental factors that enhance Acanthamoeba adhesion to corneal epithelial cells remain poorly understood. In this study, we examined the effects of domestic tap water on Acanthamoeba adhesion and found that exposure to tap water significantly increased the number of adherent trophozoites, potentially enhancing their cytopathic effects on corneal cells. We hypothesized that the calcium ions present in tap water may play a key role in regulating amoebal adhesion. To investigate this further, we analyzed the expression levels of several adhesion-related genes following exposure to different water conditions. Our findings suggest that tap water facilitates Acanthamoeba attachment and may contribute to disease progression. Understanding the role of calcium and other potential regulatory factors in adhesion may provide new insights into Acanthamoeba keratitis pathogenesis and aid in the development of preventive strategies.

The tropical bont tick, Amblyomma variegatum, is endemic in sub-Saharan and southern Africa, as well as several Caribbean islands. This tick is deleterious for the general health of ruminants and is the primary vector of Ehrlichia ruminantium, the causative agent of heartwater. Understanding the ecology and biology of A. variegatum is thus crucial to describe tick-host-bacteria interactions and thus develop effective control methods. To better understand vector competence, detailed functional characterization and precise isolation of tick organs is needed. All procedures described in this study were performed using a simple, high-quality binocular magnifying glass. Following this approach, we present descriptions and illustrations of the internal anatomy of A. variegatum at male, female (at various stages of engorgement), and nymph stages. This study focused on critical tissues associated with vector competence, including midguts, salivary glands, or ovaries, which were targeted and isolated. We identified morphological differences in the reproductive systems of both A. variegatum male and female ticks when compared with other tick species. We also provide numerous practical and technical aspects for obtaining organs suitable for detailed studies. The method presented here ensures organs of high quality, without degradation or contamination, as required for cellular or molecular studies on host-vector-pathogen interactions.