Parasite最新文献

Toxoplasma gondii infects almost all warm-blooded animals, including marine mammals. Toxoplasmosis has been reported in wild and captive marine mammals in North America; however, no viable T. gondii strains have been isolated from northern fur seals. In this study, reproduction and T. gondii infection status were investigated in 10 northern fur seals (Callorhinus ursinus), from tissues collected from 2012 to 2024 in China. Toxoplasma gondii infections were determined by the modified agglutination test (MAT), PCR, immunohistochemical (IHC) staining, and isolation of the parasite by bioassay in mice. MAT was performed using placenta or tissue exudates to detect anti-T. gondii IgG antibodies. Four of the 10 seals had anti-T. gondii antibodies; Toxoplasma gondii DNA was detected by PCR in placenta tissues of two of these four animals, and T. gondii antibody positive reactions were observed in four seals by IHC. A viable T. gondii strain, TgFurSealCHn1, was isolated from placenta of one seal by bioassay in mice. In all, five seals had signs of T. gondii infection, and three of them had fetal stillbirth. One stillborn fetus had T. gondii nucleic acid detected by PCR, indicating potential vertical transmission of the parasite. Multilocus genetic typing of the TgFurSealCHn1 isolate revealed ToxoDB #5 genotype, which had demonstrated avirulence in Swiss Webster outbred mice, and the ROP18/ROP5 type was 2/2. ToxoDB #5 is the dominant genotype of wild terrestrial and marine mammals in North America. This is the first report of a viable T. gondii strain isolated from northern fur seal placenta.

According to the classical Enemy Release Hypothesis, one reason for the success of invasive species is that they have escaped their predators and parasites during migration to newly invaded territories. In this context, the discovery of any parasite of an invasive species is of particular interest. Here, we report the results of genomic investigations performed on two invasive species of land flatworms (Geoplanidae) collected in Northern Ireland, Kontikia andersoni Jones, 1981, and Australoplana sanguinea (Moseley, 1877). We describe the mitogenomes and paralogous RNA genes of both species. Prey DNA was detected in both flatworm species, providing molecular evidence that their diet includes earthworms. Unexpectedly, we detected sequences assigned to the microsporidian genus Mitosporidium Haag et al., 2015, which, prior to this study, included a single species. Each land flatworm species harboured its own species of Mitosporidium. For nomenclatural reasons, we could not assign binomial names to these species; instead, we designate them as Mitosporidium sp. JL467 (in K. andersoni) and Mitosporidium sp. JL472 (in A. sanguinea). For each new Mitosporidium species, we describe the gene content of the mitogenome and the complete cluster of nuclear ribosomal RNA genes. In the absence of direct evidence of host-parasite relationships, we discuss the possible hosts of these Microsporidia, which could be the flatworms themselves or their prey; the most likely hypothesis is that they are parasites of land flatworms. Other Mitosporidium species should be sought for in native land flatworms from the Australasian region, where the two invasive flatworm species originated. Investigations on the possible pathogenic role of these parasites are needed.

This study reports the results of a nationwide parasitological survey that was conducted from 2019 to 2022 to investigate the potential introduction of monogenean parasites into India via the ornamental fish trade. A total of 619 individual exotic ornamental fish representing 27 teleost species from nine families were collected from the country's major aquaria markets and examined for monogeneans. To identify monogeneans at the species level, we employed a morphometric analysis of sclerotised structures (haptoral and reproductive hard parts), as well as a molecular analysis of nuclear 28S rRNA and ITS2 regions. Indian conditions for importing exotic ornamental fish species require a pre-quarantine certificate, quarantine treatment, and post-quarantine follow-up. Despite these restrictions, 26 monogenean species from 12 known genera were detected and identified in 17 of the 27 fishes examined. Dactylogyrus was represented by a maximum of nine species, followed by Gyrodactylus with five. Cyprinidae was the most parasitised fish family (13 species), followed by Cichlidae (three species) and Helostomatidae, Poeciliidae, and Serrasalmidae (two species each). The majority of co-transported parasite species originated from Asia (65.38%, n = 17), followed by South America (23.07%, n = 6), North and Central America (7.69%, n = 2), and Africa (3.5%, n = 1). Three fish species were identified as the first host records for monogenean parasites: Chindongo socolofi for Cichlidogyrus tilapiae Paperna, 1960, Metynnis hypsauchen for Mymarothecium sp., and Betta splendens for Heteronchocleidus sp. In general, exotic populations had fewer parasite species than in their native distribution ranges.

Parasitic infection by endoparasites is heterogeneous within a population. Such heterogeneity in parasitic status among individuals depends in particular on differences in their susceptibility to infection and in the habitats and resources used by the individuals. While several studies have aimed to identify individual factors and, mostly at large spatial scales, environmental factors that influence endoparasitism in wild populations, we aim in this study to investigate the influence of habitat quality (vegetation type, resource availability) on parasite burden within a population of roe deer living in a heterogeneous forest. We collected 1,469 fecal samples to measure the parasite burden on 952 roe deer captured between 1996 and 2020 in Chizé (France), a study site stratified into two contrasting sectors in terms of vegetation structure and resource quality. We quantified the effect of the sector on parasitism after considering the possible influences of age, sex, body mass and Julian date. The prevalence of parasitism was higher in individuals living in the poorer sector, but the intensity of the parasite burden was not influenced by the sector. These results suggest that within a host population, parasite infection risk would not be the same everywhere, probably due to differences in resource availability, vegetation species and density of host, showing the need to study parasitism at fine scales.

To examine the prevalence of E. bieneusi and Blastocystis sp. in foxes in China, this study analyzed the prevalence and distribution of genotypes or subtypes. A total of 352 fresh fecal samples were collected from foxes across five provinces in northern China and analyzed using PCR. The overall prevalences of E. bieneusi and Blastocystis sp. were 48.3% and 2.0%, respectively; the highest prevalences were found in Shandong Province, with 87.1% and 5.4%, respectively. The prevalence rates were influenced by several factors; a breeding scale value <1,500 was related to higher prevalences. Multivariate analysis showed that the region and breeding scale were the main risk factors for E. bieneusi. Eleven genotypes of E. bieneusi were identified, all of which are classified within Group 1. This includes five previously characterized genotypes and six novel genotypes. Among these, CHN-F1 was the predominant genotype, accounting for 67.7% of cases. Blastocystis sp. was detected with only one subtype (ST3), which represents the first report of this genotype in foxes. The identification of E. bieneusi in foxes and the first detection of the ST3 subtypes of Blastocystis sp. contribute to a more comprehensive understanding of the epidemiology of these microeukaryotes. These findings suggest a potential pathway for the transmission of microeukaryotes from fox farms to human populations, underscoring the importance of monitoring the public health risks.

Schistosomiasis is a neglected tropical disease that causes a significant global burden. The aim of this study was to report the latest estimates of the global, regional, and national schistosomiasis disease burden and forecast changes in schistosomiasis-related disease burden. This work was based on the 2021 Global Burden of Disease (GBD) study. We analyzed the schistosomiasis data by sex, age in years, and Socio-Demographic Index (SDI) region and country, using Age-Standardized Rates (ASR) for comparisons among different groups. The Estimated Annual Percent Changes (EAPC) analysis was used to evaluate the temporal trend of the disease burden, and the Differential Autoregressive Integrated Moving Average (ARIMA) and Exponential Smoothing (ES) models were used to predict the disease burden from 2022 to 2046. In the GBD 2021 study, it was reported that compared to 1990, the number of deaths has decreased by 74,350, the prevalence number has increased by 1,482,260, and Disability-Adjusted Life Years (DALYs) have decreased by 1,770,436. Additionally, the age-standardized mortality rate (ASMR) has decreased by 0.31 per 100,000 people, with an EAPC of -0.353 (95% CI: -0.361 to -0.344). Similarly, the age-standardized DALYs rate (ASDR) has decreased by 15.45 per 100,000 people (EAPC: -1.56, 95% CI: -1.78 to -1.34), and the age-standardized prevalence rate (ASPR) has decreased by 559.64 per 100,000 people (EAPC: -0.63, 95% CI: -0.95 to -0.31). The regions and countries with the highest disease burden are mostly concentrated in Africa. Despite a general decline in global schistosomiasis burden indicators, the burden of disease has actually increased in high SDI areas. The ARIMA and ES models forecast results show that female mortality and ASMR will decline in the next 25 years, while male mortality and ASMR will remain stable, and other disease indicators will continue to decline. The global schistosomiasis burden has significantly decreased over the past 30 years, but it remains high in African regions and countries, as well as low-SDI areas. Effective cooperation among countries should be strengthened to improve the disease burden in high-burden areas and countries.

The aim of this study was to clarify the taxonomic identification of a hemoflagellate and assess the effect of trypanosome infection on Larimichthys crocea. Giemsa staining showed the presence of three morphotypes of trypomastigotes. The trypanosomes had the following morphological characteristics: a slender body with a long flagellum at the front; body size 12.30-30.90 × 1.13-2.33 μm; elongated oval nucleus situated in the median region; kinetoplast small, oval, located at the posterior end. The parasite had significant morphological differences from Trypanosoma epinepheli Su, Feng, Jiang, Guo, Liu & Xu, 2014 and Trypanosoma carassii (Mitrofanov) Doflein, 1901. The 18S rDNA sequences of the trypanosome from L. crocea had the highest homology (98.4%) with T. carassii. Phylogenetic analysis indicated that the parasite clustered with freshwater fish trypanosomes. Based on the differences in morphological characteristics and molecular data, it is considered a new species, Trypanosoma larimichthysi n. sp. Trypanosome infection had no effect on the growth of L. crocea, but significantly increased the concentration of blood urea nitrogen (BUN), and induced pathological changes in the gills, liver, spleen and kidney. The pro-inflammatory immune genes, including TNF-α, IFN-γ, IL-1β, CXCL8 and iNOS, were significantly upregulated in the L. crocea infected with trypanosomes. These results suggest that the trypanosome has negative impacts on host health.

The pindani, Chindongo socolofi (Cichliformes, Cichlidae) is a popular freshwater ornamental fish from Lake Malawi in Africa. Although identifying parasites associated with the global ornamental fish trade is critical for developing biosecurity practices, little is known about the parasite fauna of C. socolofi. Therefore, this study sought to determine what monogenean parasites C. socolofi harbours in India. Adult specimens of this host species were collected from various aquarium shops across the country between 2020 and 2022, and their gills were subjected to parasitological examination. Monogeneans were detected in five host specimens (22.7%) with low mean intensities (6.2 ± 3.8). They were identified as Cichlidogyrus tilapiae (Monogenea: Dactylogyridae) based on the presence of the following morphometric characteristics: two pairs of anchors, two auricles on the dorsal bar, a V-shaped ventral bar, and an accessory piece with a folded rim and a bent bifurcated tip. The morphological identification was confirmed by the sequence analysis of the specimen's 18S-ITS1 gene regions and 28S rRNA genes to C. tilapiae from Paratilapia polleni (Cichliformes, Cichlidae) in Madagascar. This article is the first report on a species of Cichlidogyrus in India, found in aquarium shops, contributing to the growing list of known freshwater monogeneans that are being distributed globally via the ornamental fish trade. Additionally, it adds a new host species (C. socolofi) and geographic location (India, within aquarium trade) to the existing knowledge of C. tilapiae, a widespread and often co-introduced tropical fish parasite.

Reverse vaccinology is a time- and cost-effective approach to identify potential vaccinable antigens for further in vivo experimental validation. Despite its wide application to multiple organisms, the use of in silico vaccine development tools to parasitic nematodes has been limited. Herein, we have used the rodent hookworm Nippostrongylus brasiliensis as a mouse model for the human hookworm Necator americanus to identify potential vaccine candidates against the latter. Our strategy combined advanced bioinformatic evaluations with knowledge-based criteria. A cumulative rating of antigenic properties was performed resulting in a global prioritization scoring for an updated N. brasiliensis proteome of 22,796 proteins assigned. Evaluation criteria included homology to the human counterpart N. americanus, absence of mammalian homologs, cellular location by computational predictors, as well as mass spectrometry data, proteolytic activity of the evaluated protein within the parasite, presence of conserved domains, predicted humoral epitopes, and MHC class II epitope population coverage. To assign one global score representing these characteristics, cumulative scoring was performed. This analysis provided a group of 56 potential candidates, including 11 proteins associated with parasite survival and establishment. Remarkably, the second highest score was assigned to an aspartic protease homologous of the N. americanus vaccine-candidate Na-APR-1, which supports the relevance of this approach. Allergenicity and toxicity of the selected molecules were also predicted to anticipate side effects of future candidates. This comprehensive approach provides valuable insights for the rational design of new vaccines against N. americanus, the results of which, however, must be validated in vivo.

Species of Seuratascaris Sprent, 1985 are a rarely reported group of ascaridoid nematodes, parasitising various frogs and toads. In the present study, a new subspecies of Seuratascaris, S. physalis bazhaiensis n. subsp. was described using integrated taxonomic methods, based on specimens collected from Odorrana graminea (Anura: Ranidae) in Guangxi Zhuang Autonomous Region, China. Results of the Assemble Species by Automatic Partitioning (ASAP) and Bayesian inference based on the mitochondrial cox1, cox2 and rrnS data all supported S. physalis bazhaiensis representing a distinct taxon from the nominate subspecies S. physalis physalis. Supplementary morphometric and genetic data of S. phy. physalis are presented based on newly collected material from Odorrana tiannanensis (Anura: Ranidae) and Rhacophorus sp. (Anura: Rhacophoridae) in Yunnan Province, China. A key to species of Seuratascaris is provided. The complete mitochondrial genome of S. physalis bazhaiensis was sequenced and annotated, and represents the first mitogenomic data for the genus Seuratascaris. This mitogenome has only 13,628 bp (including 12 protein-coding genes, 22 tRNA genes, 2 ribosomal RNAs, and only 1 non-coding region), and is the smallest of the reported ascaridoid mitogenomes so far.