Parasite最新文献

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.

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.

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.

Avian coccidiosis significantly impairs intestinal health in chickens and remains a major threat to the poultry industry worldwide. Frequent co-infections with three Eimeria species, i.e., Eimeria tenella, E. necatrix, and E. maxima, present challenges for effective vaccine development. Here, we first used two-dimensional gel electrophoresis and silver staining to identify 650 E. tenella sporozoite proteins and then detected 18 cross-reactive immunogens based on Western blotting and proteomic analysis. These immunogens were consistently recognized by hyperimmune sera raised against three Eimeria species of interest. Bioinformatics analysis revealed that these proteins encompass enzymes, motility-related proteins, nuclear factors, and translation machinery, with amino acid sequence identities ranging from 71.1%-98.8% with E. necatrix and 37.9%-87.5% with E. maxima homologues. Seven of these proteins show potential non-classical secretion, and four have transmembrane domains. Overall, these findings point to multiple cross-reactive immunogens as potential candidates for multivalent coccidiosis vaccines.

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.

Leucocytozoon species are common in countries with warm climates but are an often neglected blood parasite in poultry. Although Leucocytozoon macleani is less virulent than Leucocytozoon caulleryi, it can still negatively impact production performance. In Thailand, the available reports indicate a high prevalence of Leucocytozoon spp., but detailed morphological characteristics of the parasites remain insufficiently known. In this study, Giemsa-stained blood smears and extracted genomic (g) DNA were obtained from 60 domestic chickens (Gallus gallus domesticus). Blood smears were examined for the presence of Leucocytozoon species and their morphological characteristics were examined. A total of 60 gDNA samples were used for nested-PCR amplification of the cytochrome b gene of Leucocytozoon species, followed by sequencing and phylogenetic analysis. The microscopic and molecular examinations revealed prevalence of leucocytozoonosis in chickens of 85% and 90%, respectively. Sequence analysis indicated that several infected chickens harboured multiple Leucocytozoon lineages. Leucocytozoon macleani was morphologically identified in nine samples and could be linked to the lineages GALLUS17, GALLUS34, and the new lineages GALLUS63. The found gametocytes of L. macleani morphologically resembled those reported previously, but exhibited some distinct characteristics. Phylogenetically, the lineages of L. macleani isolated in this study grouped separately from some other L. macleani lineages deposited in GenBank. In conclusion, the prevalence of Leucocytozoon infection in chickens from Northeastern Thailand was high, with frequent co-infections by multiple lineages. Leucocytozoon macleani may exhibit cryptic specification. This study is the first report of L. macleani lineages described using MalAvi database nomenclature, alongside their morphological characteristics.

Trichomoniasis is a globally prevalent sexually transmitted disease; however, comprehensive data on its global prevalence and incidence are relatively limited. In this study, we systematically retrieved relevant articles from PubMed, Google Scholar, Scopus, Ovid-Medline, and Web of Science to analyze the prevalence of Trichomonas vaginalis and its association with various infection risk factors. Among 5,437 publications released between 1992 and 2023, 425 articles focusing on the epidemiology of T. vaginalis were identified. The results revealed a global prevalence rate of T. vaginalis of 8% (95% CI: 7%-10%), with country-specific rates ranging from 1% to 35%. The prevalence of T. vaginalis was significantly higher in the behavioral subgroups, including smoking, drug use, and not using condoms, compared to the non-infection group, with a pooled odds ratio (OR) of 1.67 (95% CI: 1.39-2.0). Furthermore, the prevalence of T. vaginalis was significantly higher in the group with other sexually transmitted infections (STIs), including HIV, HSV, and Chlamydia infection compared to the non-infection group, with a pooled OR of 2.01 (95% CI: 1.48-2.72). Finally, socioeconomic factors such as being unmarried, having a low income, and unstable employment were associated with an increased risk of T. vaginalis infection, with a pooled OR of 1.36 (95% CI: 1.10-1.66). This study has significant public health relevance for the prevention and control of trichomoniasis.