Parasite最新文献

The spread of resistance to insecticides, such as pyrethroids, in Aedes vectors increases the risk of spread of arboviral diseases. In Gabon, the insecticide resistance profiles of Ae. aegypti and Ae. albopictus species remain poorly known. During a study to monitor the dynamics of Aedes populations in Franceville, in south-east Gabon, the resistance profiles of these two species to pyrethroids, organophosphates and carbamates were assessed. Susceptibility tests on adults and synergist tests with piperonyl butoxide (PBO) were carried out as per the World Health Organization protocol. The results showed that Ae. aegypti and Ae. albopictus were susceptible to permethrin, pirimiphos-methyl and bendiocarb. However, both species were resistant to deltamethrin (mortality: 67% for Ae. aegypti; 33% for Ae. albopictus). Exposure to a 5-fold dose of deltamethrin increased mortality to 100% and 91% for Ae. aegypti and Ae. albopictus, respectively. Resistance to alpha-cypermethrin was also recorded (mortality: 82% for Ae. aegypti; 64.6% for Ae. albopictus). Pre-exposure to PBO resulted in the restoration of susceptibility to deltamethrin and alpha-cypermethrin for Ae. aegypti, and a significant increase in mortality for Ae. albopictus. These data provide the first evidence of pyrethroid resistance in Aedes in Gabon and could help to establish more effective control measures against arbovirus vectors.

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.

Ticks are ectoparasites harboring complex microbial communities, typically dominated by nutritional symbionts that produce B vitamins and sometimes including pathogens affecting human and animal health. However, ticks also host a variety of commensal microbes whose diversity remains poorly documented. In this study, we isolated and identified culturable bacteria and fungi associated with various tick species from the genera Ixodes, Dermacentor, Amblyomma, and Ornithodoros, collected from their natural habitats or hosts in France and French Guiana. A total of 111 bacterial and 27 fungal isolates were obtained which were then identified using both molecular and morphological approaches. Substantial fungal diversity was observed in a few ticks, whereas culturable bacteria displayed a broader distribution and diversity across tick species. Interestingly, the diversity of culturable bacteria and fungi revealed a microbiome structure that reflected the ecological niches of the tick host, indicating habitat-specific microbial associations and a potential ecological role in tick biology. The isolation of common gut bacteria of other arthropods, as well as the isolation of a viable entomopathogenic fungus, underscores the potential influence of these microbes on tick biology.

Congenital toxoplasmosis is a fetal infection resulting from the transplacental transmission of Toxoplasma gondii in mothers who seroconvert during pregnancy. Neonatal diagnosis has recently been improved through the identification by L'Ollivier et al. (2012) and Peyclit et al. (2023) of a pathognomonic marker for congenital toxoplasmosis: the IgM triplet, corresponding to three high molecular weight bands of 75, 90, and 100 kDa, respectively found on the mother-child immunoblot pair profile. This is a new concept, as these three IgM bands reflect an immune response targeting proteins involved in vertical transmission of T. gondii. These proteins may be T. gondii secreted or non-secreted effectors implicated in host cell invasion, immune modulation, and parasite virulence. In this study, immunoproteomic techniques allowed us to identify thirty-two relevant protein spots on immunoblot, including four specifically associated with the IgM triplet. Protein identification by LC-MS/MS revealed several T. gondii proteins as strong candidates for the IgM triplet. Each of these proteins is, directly or indirectly, involved in cellular invasion and may also play a role in transplacental transmission of T. gondii. Identifying these proteins opens several avenues of therapeutic research that could improve the management of congenital toxoplasmosis.

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.

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.

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.