Parasite最新文献

Acanthocephalans of the genus Rhadinorhynchus parasitize various marine fishes worldwide. However, the true diversity of Rhadinorhynchus is still unclear. In this study, we found an example of phenotypic variation in trunk spines of the poorly known rhadinorhynchid species R. cololabis Laurs & McCauley, 1964. According to the number and distribution of trunk spines, the present specimens of R. cololabis can be divided into two distinct morphotypes, which may erroneously be recognized as distinct taxa in the absence of molecular data. However, the Assemble Species by Automatic Partitioning (ASAP) and Bayesian inference (BI) analyses based on different nuclear and mitochondrial sequence data, all confirm that the two distinct morphotypes are conspecific, and do not represent two separate genetic lineages. Our ASAP and BI results of cox1 data also suggest that is R. villalobosi Martínez-Flores et al., 2025 is a synonym of R. trachinoti Grano-Maldonado et al., 2025, and challenge the validity of R. dorsoventrospinosus Amin et al., 2011, and R. hiansi Soota & Bhattacharya, 1981. The present findings also indicate that the number and distribution of trunk spines vary markedly in some species of Rhadinorhynchus, and care must be taken when differentiating Rhadinorhynchus species based on this feature. Additionally, the complete mitogenome of R. cololabis is presented for the first time, which has only 13,567 bp, and displays a very high level of similarity with the mitogenome of R. laterospinosus in both nucleotide sequences (94.6%) and amino acid sequences of 12 protein-coding genes (93.8%). However, comparative mitogenomics support R. cololabis and R. laterospinosus representing two separate taxa.

Canine monocytic ehrlichiosis (CME) is a globally prevalent disease with zoonotic potential primarily caused by the obligate intracellular bacterium Ehrlichia canis, transmitted by the ticks Rhipicephalus spp. to vertebrate hosts. In dogs, CME affects immune system cells, leading to subclinical infection or acute and chronic disease forms that impact multiple organs and potentially result in death if diagnosis is delayed. Diagnosis of canine ehrlichiosis is complex, typically involving cytology, polymerase chain reaction), and serological assays such as the indirect immunofluorescence antibody test (IFAT), considered the gold standard, and enzyme-linked immunosorbent assay (ELISA). Herein, we introduce EhrlichiaCHECK Ab ELISA, a novel rapid indirect ELISA for detecting anti-E. canis antibodies in canine serum or plasma samples. The assay's performance was validated using 112 canine samples (61 negative, 51 positive). Compared to IFAT, the ELISA exhibited high sensitivity (96.1%, 95% confidence interval [CI]: 85.4%-99.3%) and specificity (95.1%, 95% CI: 85.4%-98.7%). Furthermore, in comparison to the widely used commercial INgezim Ehrlichia ELISA (Gold Standard Diagnostics), EhrlichiaCHECK Ab ELISA demonstrated 98.0% agreement and enhanced specificity attributed to a more specific antigen, corroborated by bioinformatics analysis. The assay also demonstrated accuracy, with low percentage values of intra- and inter-assay coefficients of variation. In conclusion, our data suggest that the newly developed assay is a valuable tool for diagnosing E. canis infections in dogs.

Cryptosporidium spp. are zoonotic protozoan parasites that cause diarrheal disease worldwide. Rodents can harbor diverse Cryptosporidium spp. and facilitate their transmission to the environment and other hosts, including humans. However, data on Cryptosporidium infection in wild rodents in the Poyang Lake region, China's largest freshwater lake, remain scarce. Here, we investigated Cryptosporidium spp. in 273 wild rodents collected from seven sites adjacent to villages around Poyang Lake between 2022 and 2024. The rodents were identified by cytochrome c oxidase subunit I (COI) gene sequencing as Apodemus agrarius (n = 148) and Rattus losea (n = 125). Nested PCR targeting the small subunit ribosomal RNA (SSU rRNA) gene revealed an overall Cryptosporidium spp. infection rate of 16.5% (45/273, 95% CI: 12.3-21.9%), with 20.3% (30/148, 95% CI: 14.2-27.8%) in A. agrarius and 12.0% (15/125, 95% CI: 6.9-19.0%) in R. losea. Sequence and phylogenetic analyses identified seven Cryptosporidium species/genotypes: C. apodemi, C. canis, C. muris, C. suis, C. ubiquitum, rat genotype II, and rat genotype III. Notably, the detection of four zoonotic species (C. canis, C. muris, C. suis, and C. ubiquitum) highlights the potential risk of zoonotic transmission of Cryptosporidium spp. from wild rodents to humans in this region. These findings underscore the need for systematic surveillance and control of Cryptosporidium spp. in wild rodent communities around Poyang Lake.

Surra is a vector-borne disease, caused by a flagellate protozoan, Trypanosoma evansi, infecting all domestic mammals, including herbivores and dogs, and, very rarely, humans. In Tunisia, it affects mainly dromedaries (Camelus dromedarius) in the southern part of the country, causing heavy economic losses due to high morbidity, abortions and mortality. Trypanosoma evansi is mainly transmitted by mechanical vectors (Stomoxyine flies and tabanids), but also vertically, orally (to carnivores) and iatrogenically. In the present paper, we review and discuss the studies published on surra in Tunisia and show that the antibody seroprevalence in Tunisian dromedaries varies between 22.2% and 37%. The review also highlights the absence of a comprehensive database containing the most relevant information on the occurrence of T. evansi in Tunisia. We also underscore the urgent need for data collection and analyses. These data should be related to different aspects: epidemiological data (spatial and temporal distribution) and entomological data (main vectors involved in the transmission and their activity dynamics).

Leucocytozoon species are cosmopolitan and prevalent avian parasites, with some infections being lethal, mainly due to the exo-erythrocytic development of the parasite in bird tissues. The patterns of exo-erythrocytic development in Leucocytozoon spp. infections in wild birds remain poorly studied. This study investigated the development of Leucocytozoon spp. tissue stages in tits (Paridae). Great tits (Parus major), Blue tits (Cyanistes caeruleus), and Coal tits (Periparus ater) were screened for infections using an integrative approach that consisted of microscopic analysis of thin blood smears, histological techniques, chromogenic in situ hybridization (CISH), PCR-based methods, and phylogenetic analysis. In total, 41 individuals were analyzed (eight naturally infected that were selected and euthanized, and 33 found dead in the wild and opportunistically sampled). Among the naturally infected birds, all individuals that were microscopically positive for Leucocytozoon species were also PCR-positive for these parasites. Co-infections with Plasmodium spp. and Haemoproteus spp. were commonly found, mainly among the opportunistically sampled birds. Two morphotypes were identified, Leucocytozoon majoris (Laveran, 1902) and Leucocytozoon fringillinarum Woodcock, 1910. Tissue stages were present in three birds sampled exclusively during the non-breeding season, two of them with meronts developing in the kidneys and liver, and one individual with a megalomeront in the heart. All the exo-erythrocytic stages were confirmed to be Leucocytozoon spp. by CISH using a Leucocytozoon genus-specific probe. Phylogenetic analysis placed parasite lineages with different morphotypes in separate clades. The developmental patterns of exo-erythrocytic stages of Leucocytozoon spp. in naturally infected passerines are poorly understood, requiring further research.

The red-eared slider, Trachemys scripta elegans (Wied, 1938), has been introduced worldwide, partly because of the exotic pet trade in the 1980s and 1990s. When T. s. elegans is released or escapes into natural environments, it often establishes new feral populations due to its tolerance for a variety of aquatic ecosystems. Therefore, it is now considered one of the most invasive species in the world because it can compete with native turtle species. In the present study, our objectives were to identify the potential for polystome spillover and spillback resulting from the introduction of the red-eared slider into new environments in North America. Fieldwork investigations were thus conducted mainly in aquatic habitats in Florida and North Carolina, United States, but also in Connecticut, Indiana, Kansas, Maine, Nebraska and New York. Using DNA barcoding based on cytochrome c oxidase I (COI) sequences, we surveyed the species diversity of polystome within American freshwater turtles. These included T. s. elegans but also Apalone ferox, Apalone spinifera, Chelydra serpentina, Chrysemys picta, Kinosternon baurii, Pseudemys spp., Sternotherus minor and Sternotherus odoratus. Genetic evidence confirmed that invasive populations of T. s. elegans in southern Europe have transmitted their own polystomes to native host species following spillover effects, and revealed here that T. s. elegans in non-indigenous habitats in the United States acts as a new reservoir of infection for native polystomes following spillback effects, thus increasing indigenous parasite transmission in the wild. Together, these findings raise further concern about the spread of non-native turtles and their impact on parasite transmission.

Leishmaniasis is one of the most important zoonotic diseases. Recently, Leishmania (Mundinia) martiniquensis, Leishmania (Mundinia) orientalis, and Leishmania (Mundinia) chancei have been reported as new human pathogens. Trypanosomatids, apart from Leishmania spp., such as Crithidia spp., are also occasionally capable of infecting humans. Here, a one-step multiplex qPCR assay for the simultaneous identification and quantification of L. martiniquensis and L. orientalis/L. chancei and detection and quantification of trypanosomatids was developed using ITS1 as the molecular target and human RNase P as the internal control gene. The assay was evaluated using 44 positive residual DNA samples from leishmaniasis patients and 25 negative DNA samples. Results revealed that the limits of detection (LOD) of the assay for L. martiniquensis, L. orientalis, and Crithidia sp. (CLA-KP1) were 1.699 (0.0255), 1.717 (0.0292), and 1.763 (0.0882) fg/reaction (parasite equivalents/reaction), respectively. The assay had high analytical specificity. The mean Cq values of the intra-assays and inter-assays differed by less than 1, indicating the reliability of the assay. Evaluation results revealed that the assay could identify L. martiniquensis and L. orientalis in clinical samples with 100% sensitivity and 100% specificity. In conclusion, the ITS1/human RNase P multiplex qPCR assay offers a rapid and reliable diagnostic tool for identifying and quantifying L. martiniquensis and L. orientalis/L. chancei and detecting and quantifying trypanosomatids in clinical samples within a single reaction. This assay provides an advancement in the diagnostic capabilities for leishmaniasis and trypanosomatid infections, potentially improving patient management and surveillance efforts.

The quantity and quality of laboratory-reared insects are pivotal for the success of any sterile male-release program. Optimizing larval mass-rearing methods to enhance both production and quality in Aedes mosquitoes is essential to meet the growing demand from FAO/IAEA Member States for the sterile insect technique (SIT) as a component of area-wide integrated pest management to control or suppress disease vectors. This study was designed to identify the most effective feeding regime and schedule that maximize pupae production with a single tilt/sorting event and to evaluate an alternative larval-rearing unit. The results demonstrated that ingredient particle size, mosquito strain and feeding regime significantly influenced insect production and quality, underscoring the critical need to account for these factors in mass-rearing operations. A daily feeding regime of 0.17, 0.33, 0.67, 0.67 and 0.5 mg per larva was identified as optimal for both species (Ae. aegypti and Ae. albopictus) achieving up to 80 ± 2.5% male pupae recovery rate when sorted 48 h after the onset of pupation. Production outcomes were not compromised with the exclusion of feeding on Days 2 and 3. Furthermore, under the conditions of this study, the Wolbaki rack (Model WBK-P0003-V2) was shown to be sufficient for mass-rearing Aedes mosquitoes. Finally, a 4-day feeding regime was implemented in a field program on Reunion island, yielding similar pupae recovery rates and contamination as the reference regime, a significant step toward improving cost-efficiency and scaling-up the program. These findings provide valuable information for refining standard operating procedures (SOPs) for mass-rearing, thereby enhancing the efficiency and scalability of SIT programs.

The epidemiology of Toxoplasma infection is known to vary geographically, but is also likely to vary over time, under the influence of many contributing factors. Monitoring is particularly useful in the context of preventing congenital toxoplasmosis. We took advantage of the French prenatal prevention programme to retrospectively assess changes between 2017 and 2023 in seroprevalence and incidence rates of Toxoplasma infection in pregnant women and the incidence of congenital infections. We conducted a longitudinal retrospective study including all pregnancies with known Toxoplasma status followed up at Lyon's public maternity hospitals between 2017 and 2023 (71,922 pregnancies). We used a multivariable logistic regression model to identify factors (age-group, WHO region of origin, population density of the area of residence and parity) associated with seropositivity. The seroprevalence of toxoplasmosis decreased consistently from 26.4% in 2017 to 22.1% in 2023 (p = 0.003), while maternal infection incidence remained stable at 1.3/1,000 pregnancies at risk. Notably, the seroprevalence showed a linear increase with age from 18.9% in women aged 25-29 years to 38.0% in women aged ≥40 years (p < 0.001). The seroprevalence was lower in pregnant women living in rural areas [adjusted seroprevalence ratio (aPR) = 0.87, 95% CI: 0.82-0.92] and higher in multiparous women (aPR = 1.08, 95% CI: 1.04-1.12). This study confirms the ongoing decline in toxoplasmosis seroprevalence while seroconversions remained stable, indicating a need for more tests in seronegative women in the future. These findings highlight the need for ongoing monitoring and refinement of congenital toxoplasmosis prevention strategies in high-income countries.

Schistosomiasis affects over 250 million people in 78 countries. Despite praziquantel as the primary treatment, concerns about resistance in schistosomes underscore the need for alternative therapies. The success of RNA interference (RNAi) in schistosomes shows promise for identifying potential drug targets to facilitate drug discovery. Meanwhile, double-stranded RNA (dsRNA) is commonly used in functional gene analysis via RNAi, with double-stranded green fluorescent protein (ds-GFP) widely employed as a control in schistosome-related studies. However, the potential for off-target effects of dsRNAs in various biological systems raises concerns about the reliability of conventional controls in schistosome RNAi experiments. Therefore, this study aims to evaluate the safety and suitability of ds-GFP as an RNAi negative control in Schistosoma japonicum. Our data indicate that ds-GFP is innocuous and exerts no discernible impact on the host's physiology and immune responses. Comprehensive evaluations conducted in mice showed no significant alterations in body and organ weights. While a splenic immune response was observed, histopathological examinations of multiple organs confirmed the absence of significant lesions following ds-GFP treatment. Additionally, S. japonicum morphology, reproductive capacity, and host responses to parasite eggs showed no significant variations. Taken together, these findings bolster the endorsement of ds-GFP as an appropriate negative control in S. japonicum RNAi experiments, offering reliable outcomes crucial for advancing research on schistosomiasis and related parasitic diseases.