Search Results (1,267)

Dientamoeba fragilis is a protozoan of the human digestive tract, yet its transmission and pathogenic role remain poorly understood. This study aimed to evaluate its impact on the efficacy and safety of fecal microbiota transplantation (FMT) in treating recurrent Clostridioides difficile infection (rCDI). This longitudinal cohort study analyzed stool samples from FMT donors and recipients pre-treatment and at 2 and 8 weeks post-FMT. All samples were retrospectively tested using real-time PCR. Shotgun metagenomics was also performed on selected donor–recipient pairs to explore transmission. CDI cure rates, gastrointestinal adverse events (AEs), and serious adverse events (SAEs) were assessed prospectively. A total of 53 FMT were analyzed (179 samples), with 23 (43%) derived from D. fragilis-positive donor stool (4 of 10 donors, 40%). Four of 52 recipients (18.2%), initially negative and who received treatment from positive donors, tested positive post-FMT. Shotgun metagenomics could not definitely confirm transmission due to the lack of a good reference genome. No significant differences in efficacy, AE, or SAE were observed between FMT from D. fragilis-positive versus -negative donors, even in immunocompromised patients. No SAEs were attributed to FMT. D. fragilis may be transmitted via FMT without evidence of short-term clinical impact. Consequently, RT-PCR detection should be interpreted cautiously in the context of donor exclusion decisions. Full article

Bacteria use cholesterol-dependent cytolysins (CDCs) to damage eukaryotes. While well-studied in mammals, the mechanisms by which CDCs bind to and kill protozoans remain unclear. CDCs bind to the human pathogen Leishmania major but only kill in the absence of sphingolipids. The contribution of other leishmanial membrane components to CDC binding and cytotoxicity remains unknown. Here, we used genetic knockouts and inhibitors to determine the contribution of key membrane components to CDC binding and killing in L. major. We analyzed toxin binding and killing using flow cytometry and Western blotting. Loss of the virulence factor GP63 enhanced toxicity of perfringolysin O but not streptolysin O. Plasmenylethanolamine and lipophosphoglycan had minimal contributions to CDC binding and cytotoxicity. Removal of sterols protected cells from CDCs yet failed to reduce binding. We used CDCs defective in engaging glycans or cholesterol to confirm that CDCs deficient in sterol binding, but not glycan binding, could bind to L. major. Thus, in non-mammalian systems, CDCs may rely on glycans for binding, while using sterols for pore formation. This suggests that CDCs may not be sterol-specific probes in some non-mammalian systems. We conclude that early-branching eukaryotes use distinct mechanisms from mammals to limit CDC pore formation and killing. Full article

Background: Infections caused by the protozoan Trichomonas vaginalis affect millions of people worldwide and are responsible for one of the most common sexually transmitted diseases. Despite the efficacy of 5-nitroimidazoles like metronidazole, concerns regarding widespread resistance and the absence of viable alternatives for specific patient populations necessitate the development of structurally diverse pharmacological agents. In this study, we investigated the antiparasitic activity of 1,3-thiazolidin-4-one derivatives against T. vaginalis. Methods: Thiazolidines were synthesized via multicomponent reaction (MCR) using one-pot methodology and tested in vitro against the parasite and mammalian cell lines. Results: Seventy percent of the compounds showed more than 80% antiparasitic activity at 100 μM, with compounds 4a, 4b, and 4f exhibiting IC₅₀ ≤ 20 µM. None of the molecules exhibited cytotoxic against Vero CCL-81 and HeLa cells. Evaluation of the structure–activity relationship (SAR) indicates that the substituent at the nitrogen position of the heterocycle may be involved in the antiparasitic effect of these compounds. In silico studies also revealed that the three compounds possess adequate oral bioavailability and do not present mutagenic, tumorigenic or irritating risks. Finally, molecular docking predicted strong interactions of compounds 4a, 4b, and 4f with T. vaginalis enzymes lactate dehydrogenase and purine nucleoside phosphorylase; compound 4f also interacted with methionine Ƴ-lyase. Conclusions: These preliminary results suggest that 1,3-thiazolidin-4-ones are promising scaffolds for developing new trichomonacidal agents. Full article

Although a yeast-based additive was initially employed as a performance enhancer, subsequent analysis revealed high aflatoxin B1 levels in the corn silage. Therefore, the objective of this study is to determine if the use of a yeast blend in the diet of Holstein calves that consumed feed naturally contaminated with high levels of aflatoxin can minimize the negative impacts of mycotoxins on animal health, contributing to improved performance. For this, we used 24 Holstein calves (6 months old) divided into two groups: Control (n = 12; no additive) and Treatment (n = 12; 5 g additive/animal/day). During the 100-day experiment, animals were weighed, feed intake was measured, blood samples were collected to assess health, and ruminal fluid was analyzed for ruminal fermentation. We observed greater weight gain and better feed efficiency in cattle that consumed the yeast-based additive compared to the control group. Yeast ingestion increased the concentration of propionic acid in the experimental environment, as well as increasing the protozoan count. Higher lymphocyte counts combined with higher levels of immunoglobulin G in the blood of females that consumed the additive were observed. Lower activity of enzymes that are biomarkers of liver damage, as well as markers of oxidative stress, was observed when animals consumed the yeast blend compared to the control group. Lower levels of ceruloplasmin (positive acute phase protein) and higher levels of transferrin (negative acute phase protein) are indicative of an anti-inflammatory response to the additive. The results preliminarily suggest that the consumption of the yeast blend is a nutritional tool capable of acting as a performance enhancer, even under challenging conditions, such as diets contaminated with aflatoxin at levels exceeding international limits. Full article

Introduction: Chagas disease, caused by the protozoan Trypanosoma cruzi, remains a major public health concern due to the limited effectiveness of current treatments, especially in the chronic stage. Objective: Here, we wanted to advance a library of 30 N,N′-disubstituted diamines as promising antichagasic agents and gain insight into the mechanism of action. Methods: The library was evaluated for activity against the T. cruzi amastigote stage and trypanocidal efficacy. In addition, selected compounds were tested as potential polyamine transport inhibitors, and a fluorescent analog was employed to investigate compound internalization. Results: Five compounds exhibited potent activity (pIC₅₀ > 6.0), particularly those with short aliphatic linkers (3–6 carbon atoms), suggesting a structure–activity relationship favouring shorter chains. Mechanistic studies showed that compound 3c strongly inhibited polyamine transport, a vital pathway in T. cruzi, though this was not a universal mechanism among active hits, indicating the potential for multiple targets. A fluorescent analog confirmed intracellular uptake in amastigotes but lacked antiparasitic activity, likely due to disrupted pharmacophoric features. Importantly, none of the compounds demonstrated trypanocidal activity in long-term assays, and some showed cytotoxicity, particularly in the benzyloxy-substituted series. Conclusions: These findings position N,N′-disubstituted diamines as a viable scaffold for Chagas disease drug discovery. However, further optimization is required to enhance selectivity, achieve trypanocidal effects, and better understand the underlying mechanisms of action. Full article

Trypanosoma cruzi is the protozoan parasite responsible for Chagas disease, a neglected tropical disease caused by trypanosomatids. Its success as pathogen relies on remarkable metabolic adaptability, stress tolerance, and complex interactions with mammalian hosts. Among the proteins contributing to these processes, nucleoside diphosphate kinases (NDPKs) and arginine kinase (AK) have emerged as central enzymes for parasite metabolism. NDPKs, beyond their canonical role in nucleotide homeostasis, are implicated in DNA repair and oxidative stress responses and are also secreted enzymes. AK, on the other hand, serves as a unique energy-buffering system absent in mammals, supporting parasite growth and adaptation to oxidative and metabolic stresses, including modulation of host immunity. Both enzymes display distinct subcellular localizations all along the parasite and through the life cycle, linking them to multiple roles important for parasite biology and survival. Recent studies have highlighted the impact of interfering these enzymes with several compounds on the viability of the organisms, suggesting new avenues to explore them as drug targets. This review provides a general overview of NDPKs and AK in T. cruzi, aiming to underline their relevance to a broader context of trypanosomatids. Their study not only broadens our understanding of parasite biology but also opens perspectives for applied research, including therapeutic alternatives for Chagas and related diseases. Full article

The intestine is considered a habitat for both bacteria and parasites. In this study, many fecal bacterial isolates and the protozoan Blastocystis sp. were recovered from stool samples of individuals with gastrointestinal conditions. Isolated bacteria were tested for extracellular protease production, and the most potent producer was identified by 16SrDNA gene sequencing as P. aeruginosa FZM498. The enzyme was extracted and purified to electrophoretic homogeneity by the DEAE-Sepharose ion-exchanger and SDS-PAGE revealed a major band at 42.15 KDa. It exhibited maximal activity at 35 °C with thermostability at 60 °C (T_1/2 = 200.04 min). It was most active at pH 8.0 and stable at 5.0–9.5. Enzymatic activity was greatly stimulated in the presence of Fe²⁺ ions, but was repressed by Zn²⁺ and Hg²⁺ ions. Inhibition by PMSF, TLCK, aprotinin, benzamidine, and SBTI protease reagents suggests a serine protease family. The V_max and K_m dynamic constants against azocasein were 36.232 U/mL and 0.0072 mM, respectively. It exhibited the lowest K_m value against the synthetic substrate D-Val-Leu-Lys-pNA among all substrates, indicating a plasmin-like activity. Interestingly, when tested against Blastocystis sp., cysts appeared progressively shrunken, ruptured, and mycelial-like, indicating complete structural collapse with leakage of intracellular contents. The importance of this research is that it is the first study to test the anti-Blastocystis activity of an extracted bacterial serine protease from the gut. This could be a promising, eco-friendly, natural alternative as an anti-Blastocystis agent. The objective of this study was to isolate, purify, and biochemically characterize an extracellular serine protease produced by gut-associated bacteria, as well as to assess its in vitro anti-Blastocystis efficacy as a potential natural and ecologically friendly antiparasitic therapy. Full article

Thalassogenic diseases are human infections associated with exposure to marine environments. This review explores the occurrence of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. in seawater and shellfish and their implications for public health. Between 2015 and 2026, multiple studies reported the presence of these parasites in shellfish and seawater. Cryptosporidium spp. was found at average concentrations of 5.5 × 10¹ oocysts/g in shellfish and up to 3.7 × 10¹ oocysts/L in seawater. Giardia duodenalis reached 9.1 × 10¹ cysts/g in shellfish, close to the infectious dose, and 3.5 × 10¹ cysts/L in seawater. Blastocystis sp. showed prevalence rates of 33.82% in shellfish and 17.3% in seawater. These findings highlight a potential infection risk for bathers and seafood consumers, emphasizing the need to determine the specific species (or subtypes) involved and assess their viability to accurately evaluate public health implications. The persistence of these parasites in the environment needs improved monitoring. Future strategies should integrate next-generation sequencing (NGS) or use of various fecal indicators to enhance environmental surveillance and reduce health risks in coastal regions. Full article

Three-dimensional unmanned aerial vehicle (UAV) path planning presents a challenging optimization problem characterized by high dimensionality, strong nonlinearity, and multiple constraints. To address these complexities, this study proposes an Enhanced Protozoan Optimizer (EAPO) by refining the initialization, behavioral decision-making, environmental perception, and population diversity preservation mechanisms of the original Protozoan Optimizer. Specifically: Latin hypercube sampling enriches initial population diversity; a behavior adaptation mechanism based on historical success dynamically adjusts the exploration-exploitation balance; environmental structure modeling using perception fields enhances local exploitation capabilities; an adaptive hibernation-reconstruction strategy boosts global escape ability. Ablation experiment validates the effectiveness of each enhancement module, while exploration-exploitation analysis demonstrates EAPO maintains an optimal balance throughout the optimization process. Comprehensive evaluations using CEC2022 and CEC2020 benchmark datasets, ten real-world engineering design problems, and four drone path planning scenarios of varying scales and complexities further validate its excellent performance. Experimental results demonstrate that EAPO outperforms the baseline APO and twelve advanced optimizers in convergence accuracy, stability, and robustness. In UAV path planning applications, paths generated by EAPO satisfy all constraints and outperform APO-generated paths across multiple path quality evaluation metrics concerning safety, smoothness, and energy consumption. Compared to APO, EAPO achieved average fitness improvements of 14.0%, 4.5%, 8.7%, and 31.42% across the four maps, respectively, fully demonstrating its practical value and formidable capability in tackling complex engineering optimization problems. Full article

Biofilms are more than just structural microbial communities. They are dynamic chemical ecosystems that synthesize a range of extracellular compounds involved in functions that extend beyond biofilm architecture. From quorum-sensing molecules like acyl-homoserine lactones (AHLs) to short-chain fatty acids (SCFAs), phenazines, indoles, and reactive sulfur species (RSS), biofilm-derived metabolites can impact the physiology and behavior of microorganisms living in the same ecosystem, including other bacteria and protozoa. It has recently been demonstrated that such molecules may also modulate competition between microbes, promote cooperation, and impact motility, differentiation, or virulence of free-living and parasitic protozoa. This review aims to discuss biofilm compounds that mediate interspecies or interkingdom interactions and their involvement in regulating gut and environmental microbiomes functions, and host–pathogen relationships with special emphasis on protozoan activity and the infection outcome. This review will also address how this chemical dialog can be explored to identify new therapeutic interventions against microbial infections and parasitic diseases. Full article

Equine theileriosis, caused by the protozoan parasite Theileria equi, represents a significant economic threat to the equine industry. In Xinjiang, China, an endemic area for this disease, systematic research on the genetic diversity of T. equi has been notably lacking. The aim of this study was to obtain molecular epidemiological data pertaining to the parasite in selected regions of Xinjiang, China, and analyze the genetic characteristics (including 18S rRNA, EMA-1, and COI genes) and genotype distribution patterns of isolates from these regions, providing a scientific basis for developing targeted prevention and control strategies. Blood samples were collected from 440 horses across four regions (Altay, Ili, Tacheng, and Urumqi) and subjected to PCR assays. Positive samples were sequenced for phylogenetic and haplotype network analyses, and genetic diversity indices were calculated. The overall infection rate of T. equi was 38.41% (169/440), with Tacheng having the highest prevalence (86.27%) and Altay the lowest (20.88%); these regional differences were statistically significant. Phylogenetic analysis identified two genotypes of the 18S rRNA gene: genotype E (predominant) and genotype A. All EMA-1 sequences clustered exclusively within genotype A. Notably, all COI gene sequences formed a monophyletic group, exhibiting closer genetic relationships to isolates from France and Senegal. This study presents the first comprehensive genotyping of T. equi in Xinjiang based on three target genes and constructs an associated haplotype network. The analysis identified 18S rRNA genotype E and EMA-1 genotype A as the predominant genotypes. Furthermore, the genetic diversity of T. equi was found to be higher in Urumqi than in the other regions studied. Full article

Pyrimethamine (PYR), a drug approved for the treatment of infections caused by protozoan parasites, is a multifunctional API based on 2,4-diaminopyrimidine scaffold. The present study aims toward the development of novel solid forms of PYR, by combining it with three isomeric aminobenzoic acids—2-aminobenzoic acid (2NH₂-BA), 3-aminobenzoic acid (3NH₂-BA), and 4-aminobenzoic acid (4NH₂-BA). Solution crystallization led to the formation of three new solvated salts of PYR (PYR/2NH₂-BA/EtOH/H₂O, PYR/3NH₂-BA/EtOH, and PYR/4NH₂-BA/EtOH/H₂O). The detailed physicochemical properties of the formed compounds were characterized by single-crystal X-ray diffraction (SC-XRD), FTIR, PXRD, thermogravimetry (TG), and differential scanning calorimetry (DSC). Additionally, the pre-crystallization solutions of PYR with 2NH₂-BA, 3NH₂-BA, and 4NH₂-BA were studied by electrospray ionization mass spectrometry technique (ESI-MS), which enabled the observation of peaks corresponding to noncovalently bonded molecules, providing insight into their specific aggregation in a solution/gas phase environment. We identified different non-covalent aggregates, including self-aggregates of aminobenzoic acids and PYR/aminobenzoic acid associates of different stoichiometries. Full article

Chagas disease is caused by the protozoan Trypanosoma cruzi, and its current treatment is limited to the use of two nitroderivatives, benznidazole (Bz) and nifurtimox; however, their toxicity often leads to discontinuation, justifying the search for new therapeutic options. The biological activity of quinones has long shown efficacy towards pathogenic microorganisms. In our previous investigations, two naphthoquinones combining ortho- and para-quinoidal moieties exhibited remarkable trypanocidal activity and presented low toxicity to host cells. Here, these two active compounds were further assessed. On trypomastigotes and epimastigotes, brominated (NQ1) and chlorinated (NQ2) nor-beta-lapachone-derived 1,2,3-triazoles were more active than Bz, presenting IC₅₀/24 h values in the range of 0.8 to 3.1 µM. NQ1-treated epimastigotes showed a mitochondrial impairment and reactive oxygen species (ROS) production under electron microscopy and flow cytometry. The in vitro evaluation of both combinations of compounds with Bz indicated an additive interaction. In vivo, oral treatment with NQ1 reduced parasitemia in an acute model, with no evidence of toxicity. The treatment also led to a reduction in myocarditis, decreasing the PR interval in electrocardiographic analysis and reversing the sinus bradycardia caused by infection. These data suggest that T. cruzi mitochondrion are part of the NQ1 mechanism of action. In vivo, this compound presented moderate trypanocidal and promising anti-inflammatory activity. Its combination with Bz could enhance current therapeutic protocols and should be better explored in the future. Full article

Cryptosporidiosis is a globally important protozoan disease that causes severe gastrointestinal illness in immunocompromised humans and animals and has been associated with chronic wasting and death in reptiles. This study investigated the role of Cryptosporidium infection in wasting syndrome among captive leopard geckos from a commercial breeding facility in Chiang Mai, Thailand. Thirty-five geckos housed in twenty-three enclosures were observed for four months, with fecal samples collected over three consecutive days every two weeks and pooled for molecular analysis. Clinical evaluations included body weight (BW), tail diameter, and body condition score (BCS) to assess wasting. Nested PCR targeting the 18S rRNA gene and subsequent sequencing were performed. Cryptosporidium was detected in 51.43% of geckos and 52.17% of enclosures, while 20% exhibited wasting syndrome. BLAST (v. 2.17.0) and phylogenetic analyses identified C. varanii, which showed 100% identity with isolates from leopard geckos in Spain and from snakes in Thailand and China. Multivariable logistic regression demonstrated a significant association between Cryptosporidium infection and wasting syndrome (OR = 11.15, 95% CI: 1.78–69.98, p = 0.027), with persistent oocyst shedding observed. This study provides new insights into C. varanii infection among leopard gecko breeders in Thailand and highlights the potential for infected breeding stock to disseminate Cryptosporidium, underscoring the need for enhanced awareness, surveillance, and biosecurity measures across Thailand and the Asia-Pacific region. Full article

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, continues to be a significant global health issue, especially in Latin America, with increasing international prevalence due to migration. Despite advancements in diagnosis and treatment, it remains a neglected tropical disease characterized by significant morbidity and mortality, mainly influenced by the complex interaction between parasite diversity and host immune responses. Importantly, the remarkable genetic diversity of T. cruzi lineages also contributes to clinical heterogeneity, influencing immune evasion, therapeutic responses, and vaccine feasibility. This review analyzes the impact of immunogenetics on host–parasite interactions in Chagas disease and explores its implications for personalized therapy approaches. Recent research, particularly over the last decade, has indicated that processes including antigenic variation, extracellular vesicle-mediated regulation, and disruption of host signaling pathways facilitate parasite persistence. Host genetic variables significantly influence susceptibility, disease development, and treatment outcomes, including changes in Human Leukocyte Antigen (HLA) genes, cytokine gene polymorphisms, and immunogenetic determinants of cardiac pathology. These findings underscore the potential of immunogenetic markers as tools for prognosis and as targets for personalized therapies. However, there are still considerable research deficiencies. Inadequate comprehension of gene–environment interactions, lack of representation of varied populations, and inconsistencies in study design limit the use of immunogenetic findings in therapeutic settings. At present, the concept of personalized medicine in Chagas disease remains largely aspirational, better understood as a framework for precision public health or stratified interventions guided by host immunogenetic and parasite lineage data. Addressing these issues necessitates comprehensive genomic research, mechanistic investigations of host–parasite interactions, and clinical validation of genetic markers. This study emphasizes the necessity of incorporating immunogenetics into personalized patient management strategies based on existing evidence. This integration has the potential to improve diagnosis, enhance treatment efficacy, and inform preventive interventions, thereby advancing personalized therapy for Chagas disease. Full article