Parasite最新文献

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.

The potential link between the infections and the development of Alzheimer's disease (AD) has led to speculations about the role of various pathogens in triggering amyloid-β (Aβ) overproduction, possibly leading to AD onset. The globally distributed dog roundworm Toxocara canis was suggested to be a suitable candidate due to neurotropism of the larvae and infection chronicity. This study investigated whether chronic T. canis infection induces AD-like pathology in mice and whether Aβ is toxic to T. canis. BALB/c and APP/PS1 transgenic mice, which overproduce Aβ, were infected with T. canis L3 larvae and monitored for larval burden, Aβ accumulation, and behavioral changes. In vitro tests of recombinant Aβ toxicity against the larvae were also performed. Despite the presence of T. canis larvae in the central nervous system 8 and 16 weeks post-infection, no significant increase in Aβ concentration or AD-related behavioral alterations were observed. Aβ was detected on the surface and within the intestines of T. canis larvae, but in vitro exposure to recombinant Aβ did not affect larval viability or morphology. Our findings suggest that T. canis infection does not trigger AD-like pathology in mice, and Aβ does not act as an antiparasitic agent. This challenges the emerging hypothesis that chronic neurotoxocarosis infections may contribute to AD development.

Visceral leishmaniasis, a life-threatening vector-borne illness that disproportionately affects children and elderly immunocompromised people, is a primary tropical neglected disease. No apoptotic partner proteins have yet been reported in Leishmania donovani, while their identification could contribute to knowledge on parasite cell death and the establishment of alternative therapeutics. We searched for mammalian Bcl-2 family protein orthologs and found one anti-apoptotic and two pro-apoptotic orthologs in L. donovani. A pro-death aquaporin protein, due to its characteristic BH3 domain known to interact with pro-apoptotic proteins in mammalian Bcl-2 family proteins, was also included in this study. Molecular docking and molecular dynamics simulations were conducted to assess protein-protein interactions between the identified apoptotic proteins and mimic mammalian intrinsic apoptotic pathways. The results showed that both pro-apoptotic proteins interacted with the hydrophobic pocket of the anti-apoptotic ortholog, forming a stable complex. This interaction may represent a critical event in an apoptotic pathway in L. donovani. To further characterise it, we used CRISPR-Cas9 approaches to target the identified proteins. Pure knocked population mutants, and episomal over-expressing mutant cells were exposed to apoptotic stimuli. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and quantitative expression profiling suggested that these proteins are involved in the parasite's apoptosis and could play a role in its survival.

Toxocariasis is a zoonotic parasitic disease that is widely prevalent in the world. Toxocara canis adults are parasitic in the small intestinal tract of canids, and the larvae migrate to the liver and lungs before reaching the final destination. Our previous experiments have confirmed that T. canis infection could affect the composition of host intestinal microbial flora. In this experiment, we further analyze the potential effects of T. canis infection on host liver and lung microbial flora. Utilizing 16s rRNA high-throughput sequencing, coupled with various bioinformatics analysis techniques, our study revealed that T. canis infection significantly elevated the abundance of certain opportunistic pathogens in the host's liver and lungs. This marked elevation contributes to the establishment of infection. Through cluster analysis, we found that the changes in the microbiota of the liver and lungs were independent of the microbial flora carried by T. canis adults. However, whether the changes are due to the migration of larvae remains to be explored. In short, T. canis infections have a significant impact on the abundance and diversity of flora in the host tissues, and the changes in microbiota abundance and diversity could further influence tissue homeostasis and immune responses, thus regulating the establishment of infection.

Understanding why Diptera, such as mosquitoes and sand flies, feed on humans is crucial in defining them as vectors of diseases such as malaria, dengue fever, Zika virus, and leishmaniasis. Determining their attraction to humans (anthropophily) helps in assessing the risk of disease transmission, designing effective vector control strategies, and monitoring the effectiveness of existing control measures. An important question is whether they are specifically attracted to humans in preference to other mammals or whether there is something else at play. In this paper, I propose that the idea that saying species are "anthropophilic" when they are preferentially attracted to humans is misleading and that such species are generalists that will opportunistically feed on a wide range of animals including humans when they are available. Other species are specialists that, under rare circumstances, accidently feed on humans. For these groups, I propose the names anthropportunists and anthroaccidentalists, respectively. The level of contact depends on a range of environmental factors and it is these that must be considered in evaluating potential vector importance and management. In this paper, I propose a review of the Leishmania identified in American sand flies and relate them to these two concepts and how it is linked to taxonomic groups, evolution, and ecology. There are records of Leishmania in 91 species, which is only 16.5% of American sand fly species. Of these infections, 56.7% are in the genera Lutzomyia, Nyssomyia, Pintomyia, and Psychodopygus, which are typically generalist anthropportunists. Of the species considered to be proven vectors, 77.4% belong to these four genera. As infections were detected by a variety of methods, further case-by-case field studies are required to evaluate the vectorial role of many of the sand fly species in which Leishmania have been found.