Parasite最新文献

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.

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.

The fluke Clinostomum complanatum, a parasite of piscivorous birds, but also reptiles and rarely mammals, has established several foci in the western Palaearctic regions. Previous studies pointed out the complicated taxonomy of the genus, but broader population genetic analysis of C. complanatum has not yet been carried out. The aim of this study was to determine the structure, intraspecific variability, and diversity of mitochondrial cox1 haplotypes of C. complanatum from different localities in Slovakia (Danube floodplain forests) and Italy (Emilia-Romagna and Tuscany), as well as to evaluate the interrelationships among populations from Europe, the Middle East, and North Africa. The genetic structure of C. complanatum from Slovakia and Italy was represented by a great number of haplotypes, showing stable populations with high intraspecific diversity. The haplotypes of samples from other localities (Romania, Turkey, Egypt, and Iran) showed possible gene flow among the populations from Central Europe down to the Mediterranean region, North Africa, and the Middle East. The genetic homogeneity of these samples can be linked to the distribution and migratory routes of the definitive hosts, aquatic piscivorous birds, mainly herons and cormorants, that spread parasite eggs among the continents.

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.

Culicoides biting midges (Diptera: Ceratopogonidae) have been reported as potential vectors for haemoparasites. Information about host-vector-parasite specificity is required to confirm their status. Here, molecular detection of haemosporidians, Leishmania, trypanosomatids, and filarial nematodes in biting midges was conducted to understand their potential role as vectors, and their host preference was determined. Wild-caught biting midges were collected from six different localities of Chiang Mai and Nakhon Si Thammarat provinces, Thailand. A total of 6,578 individual Culicoides (170 males, 6,408 females) comprising 15 species of six sub-genera and two groups were collected. Also, 738 parous females and 29 engorged females were examined for parasites and host blood meals, respectively. Culicoides arakawae, C. mahasarakhamense, C. peregrinus and C. innoxius in Chiang Mai province, and C. innoxius and C. peregrinus in Nakhon Si Thammarat province were the most dominant species. Leucocytozoon spp., Leucocytozoon caulleryi and Plasmodium juxtanucleare were identified in five Culicoides species including C. mahasarakhamense, C. arakawae, C. oxystoma, C. fulvus, and C. guttifer. This study is the first record of L. caulleryi in the biting midge C. arakawae in Thailand. Blood meal analysis revealed that Culicoides primarily fed on cattle (17/29, 58.6%), followed by chickens (10/29, 34.5%), and humans (2/29, 6.9%). Our findings confirmed the existence of several Culicoides species in Thailand, which might be potential vectors for transmission of haemosporidians (Leucocytozoon and Plasmodium). Information from host blood meal analyses underlined their preference for large mammals, followed by domestic chickens. More anthropophilic Culicoides species remain to be discovered.

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.

Vector control (VC) is one of the strategies employed to manage African trypanosomoses. This study aimed at assessing the effectiveness of a VC campaign against Glossina palpalis palpalis using tiny targets (TTs) impregnated with insecticide in an isolated, protected forest in Abidjan, Côte d'Ivoire, while considering ecological, genetic, and operational factors. Between January 2020 and September 2022, 2,712 TTs were deployed at 684 sites, covering a total area of 1.7 km². VC monitoring was conducted using Vavoua traps during 12 evaluation surveys, between June 2020 and March 2023. Five months after the initial TT deployment, tsetse fly density had decreased by 98.53%. Although tsetse density remained low due to TT redeployment and reinforcement, there was a significant increase a few months after the last redeployment. VC appeared to have minimal impact on the genetic structuring of G. p. palpalis. This suggested recruitment of local surviving tsetse flies all along the VC campaign due to a low probability of tsetse coming into contact with TTs, or to the evolution of behavioral or physiological resistance to control efforts. The genetic study revealed that one of the microsatellite markers used, the GPCAG locus, exhibited a selection signature possibly in response to VC. This could partly explain the challenges encountered in eliminating a seemingly isolated tsetse population thriving in a particularly favorable habitat.