Search Results (657)

Background: Large language models (LLMs) are increasingly considered as adjuncts for differential diagnostic reasoning, yet their sensitivity to gender-attributed cues in the persona prompt—particularly for neglected tropical diseases (NTDs) and in non-English clinical settings—remains poorly characterised. Objective: The objective of this study was to compare the diagnostic accuracy of one proprietary and three open-weight LLMs for Chagas disease (CD) and visceral leishmaniasis (VL) under paired persona-prompt conditions in which the only manipulated variable was the linguistic gender of the simulated medical persona. Methods: This experimental, paired study evaluated ChatGPT-4o, LLaMA 3 70B, Meditron-70B, and Mixtral 8x7B across 12 cases per disease (n = 24) from real records at a Brazilian teaching hospital. The primary outcome was top-five diagnostic accuracy. A committee of five infectious-disease specialists assessed the biological plausibility of all differentials. Paired comparisons used Wilcoxon signed-rank tests; 95% confidence intervals were calculated using the Wilson-score method. Results: ChatGPT-4o achieved the highest accuracy (CD: 100% under both prompts; VL: 83.3–91.7%). LLaMA 3 70B and Mixtral 8x7B showed moderate performance (41.7–83.3%); the medically fine-tuned Meditron-70B exhibited paradoxically poor accuracy (16.7–25.0%) and the lowest committee-rated plausibility scores. A consistent small numerical trend favoured the female prompt across most model–disease combinations (differences of 0–16.7 percentage points), but no comparison reached statistical significance (all p > 0.05). Conclusions: Gender-attributed persona-prompt variation did not produce a systematic effect on LLM diagnostic accuracy for CD or VL. ChatGPT-4o outperformed the three evaluated open-weight alternatives, and medical-domain fine-tuning did not confer the expected advantage. Expert-validated assessment of hypothesis plausibility should complement target-disease accuracy in clinical LLM evaluation studies, particularly for NTDs. Full article

Background: Neglected diseases caused by protozoan parasites remain a major public health burden, particularly in low- and middle-income countries. Among the chemical motifs explored in antiparasitic drug discovery, guanidine-containing compounds have attracted considerable attention due to their strong cationic character, high capacity for hydrogen bonding, and versatility in interacting with biological targets. Methodology: This review summarizes advances reported in the last decade regarding guanidine derivatives with activity against pathogens associated with Chagas disease, human African trypanosomiasis, Leishmaniasis, tuberculosis, toxoplasmosis, dengue and schistosomiasis. Results: Evidence gathered from synthetic, natural, and drug-repurposing studies indicates that the guanidine, guanidine-containing and guanidine-related compounds contribute to modulating biological activity by changing electrostatic interactions, hydrogen-bonding networks, and physicochemical properties, with enzymes, nucleic acids, and membrane-associated targets essential for parasite survival. Across the analyzed studies, several emerging structure–activity relationship trends were identified, including the contribution of polycationic or dicationic architectures, the influence of halogenated or lipophilic substituents, and the dependence of biological activity on the complete molecular framework, including heterocyclic systems, macrocycles, peptide conjugates, hybrid scaffolds, and repurposed drugs. In addition to direct antiparasitic effects, certain guanidine-containing and guanidine-related compounds demonstrate immunomodulatory or host-protective properties, expanding the therapeutic relevance of this class. Despite promising in vitro results, protonation trapping, efflux pump susceptibility, and pharmacokinetic limitations such as poor oral absorption, high polarity, plasma protein binding and limited membrane permeability remain significant challenges for clinical translation. Nonetheless, the integration of medicinal chemistry, computational modeling, and biological screening continues to accelerate the identification of optimized scaffolds. Conclusions: Overall, guanidine-based compounds constitute a promising scaffold for the development of new therapeutic strategies targeting neglected parasitic diseases, and further structural optimization may enable the emergence of candidates with improved efficacy, selectivity, and drug-like properties. Full article

Different protozoan parasites are the causative agents of tropical diseases, including malaria, toxoplasmosis, leishmaniasis, and Chagas disease (CD), which, altogether, affect over 300 million people throughout the world. Except for two recently approved malaria vaccines, individuals affected by or at risk of contracting any of these four diseases still experience a lack of effective treatments and vaccines. Many vaccine studies, including those that have reached clinical trials, are based on inactivated parasites, adjuvanted recombinant proteins, or viral vector vaccines. Here, we review the current advances towards the development of vaccines based on genetically modified live-attenuated parasites (GMLAP) as well as RNA formulations encoding parasite antigens. Because these are diseases caused by intracellular pathogens that depend on efficient T-cell responses for parasite control, these two new vaccine platforms have generated great expectations, since they are known to induce a robust cellular immune response. Although preclinical studies aimed at developing new malaria, toxoplasmosis, and leishmaniasis vaccines have led to significant progress that may soon result in clinical trials, advances in next-generation vaccines against CD are lagging behind. Increased collaborative efforts between research groups, governments, and the pharmaceutical industry, particularly in Africa, Asia, and Latin American countries, are urgently needed to accelerate the development of vaccines for all neglected and less-studied diseases. Full article

Chagas disease and trichomoniasis are two neglected parasitic infections (NPIs) in need for new therapies that address both the toxicity and limited bioavailability impacting on the effectiveness of benznidazole (BZ) and nifurtimox, the only drugs available for treating the infection caused by Trypanosoma cruzi, as well as the resistance that Trichomonas vaginalis has developed to 5-nitroimidazoles. Herein, we report the outcomes of the primary screening of a series of eighteen quinoxaline-1,4-di-N-oxides (QdNOs) carried out against both protozoan parasites. Computational approaches revealed that these derivatives have adequate oral bioavailability and do not pose toxicity risks associated with their chemical structures. Meanwhile, biological studies disclosed that compounds 4b and 4m exhibit considerable activity against T. cruzi at the highest concentration tested, showing 4m a trypanocidal profile (IC₅₀ = 23.66 µM) similar to that of BZ (IC₅₀ = 21.66 µM), and a selectivity index (SI) > 5.32. Regarding the activity on T. vaginalis, derivative 4n stands out with an IC₅₀ value of 9.85 µM, showing no cytotoxicity towards mammalian cells. However, their potency decreases when tested over resistant parasites. Alterations in either the hydrogenosomal membrane potential or the production of reactive oxygen species (ROS) were also explored. The findings suggest that the trichomonacidal activity of compound 4n is not mediated by a direct disruption of hydrogenosomal bioenergetics or a pro-oxidant effect. Altogether, these preliminary results support that the QdNO scaffold could be introduced as a proper template for developing novel trypanocidal and trichomonacidal agents. Full article

Chagas disease remains a major neglected parasitic illness in Latin America and other endemic regions, and benznidazole (BZN) is still the primary trypanosomacidal drug despite its incompletely understood mechanism of action. This work provides a detailed biophysical characterization of the conformational behavior and vibrational properties of benznidazole (BZN), a first-line trypanocidal drug still widely used for the treatment of Chagas disease. Using density functional theory combined with relaxed potential energy surface scans in vacuum and implicit water, two low-energy conformers (BZN1 and BZN2) were identified, separated by moderate rotational barriers and a small energy difference, indicating that both are intrinsically accessible at room temperature. For each conformer, infrared and Raman spectra were calculated and assigned via vibrational mode analysis, then compared with FT-IR and FT-Raman spectra recorded for pharmaceutical-grade polycrystalline BZN. The theoretical and experimental spectra show excellent agreement, with a Raman band in the 1350–1400 $\mathrm{c}{\mathrm{m}}^{-1}$ region emerging as a sensitive conformational marker: the experimental maximum at $1359\mathrm{c}{\mathrm{m}}^{-1}$ matches the most intense BZN1 mode, whereas the corresponding BZN2 band appears about $13\mathrm{c}{\mathrm{m}}^{-1}$ higher in frequency. This clear spectroscopic fingerprint demonstrates that the solid drug is overwhelmingly composed of the BZN1 conformer, despite the theoretical accessibility of BZN2. Overall, the study links the conformational landscape of benznidazole to its vibrational signatures and highlights Raman spectroscopy, supported by quantum chemical calculations, as a powerful tool for conformational and potential polymorphic control of this clinically important nitroimidazole. Full article

Food deprivation induces intestinal adaptations in Triatoma pallidipennis, a hematophagous insect with intermittent feeding habits. The ability to survive long periods without food promotes the persistence of this vector in the environment and contributes to its evolutionary success. This study employed one- and two-dimensional electrophoretic techniques combined with Western blot to evaluate the abundance of α-tubulin, β-actin, and the heat shock protein HSP70. These proteins were more abundant in the anterior midgut tissue of unfed insects than in that of fed insects. As these responses were similar in females and males, the observed adaptations primarily depend on feeding status and intestinal region. These findings provide further insight into the intestinal physiology of T. pallidipennis, a vector of the flagellate parasite Trypanosoma cruzi, the causative agent of Chagas disease. Full article

Chagas disease affects millions of people worldwide, including those in Latin America. The only drugs available for its treatment are benznidazole and nifurtimox. However, these drugs present high toxicity and limited efficacy. Therefore, the search for new treatments continues. In this regard, computer-assisted drug design has been implemented in scientific research for drug repurposing, allowing for reduced costs and time. Therefore, the objective of this work was to search for analogs of FDA-approved drugs with activity against Trypanosoma cruzi through ligand-based virtual screening and their biological evaluation against blood trypomastigotes. The compound TD-095 (LC₅₀ = 48.60 and 13.75 µM), a ketanserin analogue, TS-936 (LC₅₀ = 71.55 and 37.54 µM), a terfenadine analogue, and TD-831 (LC₅₀ = 75.94 and 26.17 µM), a sulfasalazine analogue, were considered as potential trans-sialidase inhibitors; TIM-967 (LC₅₀ = 69.70 and 39.69 µM) and LK-284 (LC₅₀ = 116.7 and 82.29 µM), two sulfonylurea analogues, were considered as potential triosephosphate isomerase inhibitors, showing better trypanocidal activity against NINOA and INC-5 strains, respectively, than the reference drugs. Molecular dynamics simulations predicted the stability of the compounds in complex with their respective proteins. Finally, the ADMET predictive analysis showed favorable properties for the compounds. These results support continued research into new agents against Trypanosoma cruzi, using structures of drugs already approved by the FDA. Full article

Chagas disease (CD) is a neglected tropical disease caused by the flagellate protozoan Trypanosoma cruzi, representing a major socioeconomic challenge. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression, and several pathogens, including T. cruzi, can modulate host miRNA networks. In this context, we hypothesized that host-derived miRNAs could serve as biomarkers in chronic CD. Given the intrinsic lability of RNA, we evaluated the efficacy of a 6 M guanidine-HCl/0.2 M EDTA solution, widely used in the molecular detection of T. cruzi DNA, in preserving mRNAs and miRNAs when mixed in a 1:1 ratio with human blood. Samples with or without guanidine were enriched with exogenous miRNAs (cel-miR-39 and cel-miR-54) and stored at 4 °C. RNase P expression was also evaluated in blood samples stored for up to 120 days and in samples from patients with CD, allowing direct comparison of mRNA stability over time. Samples preserved with guanidine-EDTA showed Ct values that were 4 to 5 cycles lower for all targets analyzed and demonstrated greater RNA stability over time. Taken together, these findings demonstrate that guanidine-EDTA robustly preserves mRNA and miRNAs in human blood, expanding the feasibility of molecular analyses in retrospective samples and corroborating its potential application in the studies of biomarkers of therapeutic response and prognosis in CD. Full article

Chagas disease, caused by Trypanosoma cruzi, affects 7 million people. Studying the ecology of triatomine vectors through midgut content analysis allows for infection diagnosis and the identification of blood meal sources (BMSs). Current BMS methodologies are limited by the accuracy of genetic data for local fauna, limiting species identification of hosts involved in parasite transmission. Here, we performed a systematic review on BMSs of T. cruzi vectors and showed the geographical distribution by T. cruzi lineages and vertebrate orders. We propose a decision tree system combining ecological and taxonomic approaches (EcoTaxDT) to discriminate ambiguous BMS results. The EcoTaxDT was validated using published and new BMS results. The review highlights the growing number of BMS studies and the awareness of host species potentially involved in transmission cycles. In Brazilian studies, EcoTaxDT allowed for taxonomic assignments when genetic identity was insufficient or when identified taxa had no geographical occurrence. New BMS results, validated by EcoTaxDT, showed triatomines feeding on Natalus macrourus, Echimyidae, Tettigoniidae, and Tropidurus itambere. Reliable BMS data and T. cruzi diagnosis are crucial for understanding transmission dynamics and human infection risk. EcoTaxDT is functional in correcting inconsistent BMS outputs, ensuring robust and consistent results by integrating genetic, taxonomy, and species geographical distribution. Full article

In this study, a drug repurposing strategy was implemented with the aim of identifying new trypanocidal agents against Trypanosoma cruzi (T. cruzi). A total of 924 Food and Drug Administration (FDA)-approved drugs were screened by molecular docking on three sites of trypanothione synthetase (TS), including the catalytic site, a blind docking site, and a potential allosteric site. Selected compounds were further evaluated through in vitro and in vivo assays. Tadalafil, Zafirlukast, Raltegravir, and Olmesartan had better trypanocidal activity than the reference drugs Benznidazole and Nifurtimox in the in vitro evaluation against the trypomastigote form. Additionally, these drugs were able to decrease parasitemia by 20–50% in mice in an acute treatment. Molecular dynamics simulations (MDS) at 120 ns helped link findings from in vitro/in vivo experiments to a potential mechanism of action targeting T. cruzi trypanothione synthetase (TcTS). Therefore, the results encourage the use of these drugs to develop new anti-T. cruzi agents. Full article

Background/Objectives: Protein kinases play crucial roles in signal transduction pathways that regulate growth and differentiation in Trypanosoma cruzi. These protein kinases are attractive targets to develop new drugs to treat Chagas disease. Methods: We used several protein kinase inhibitors targeting the p38 MAPK, MEK, and ERK pathways to evaluate their effects on the in vivo phosphorylation status of T. cruzi proteins, particularly DNA polymerase beta (TcPolβ). We also used Genistein, a protein tyrosine kinase inhibitor, to assess its effects on global protein phosphorylation and TcPolβ phosphorylation. Also, we investigated the effect of oxidative stress on global tyrosine phosphorylation. Finally, we determined the phosphorylation sites on TcPolβ by the protein kinases TcPKC2 and TcWee570 in vitro. Results: p38 MAPK and MEK protein kinase inhibitors inhibited approximately 50% of the Ser/Thr phosphorylation of TcPolβ. Genistein inhibited both Ser/Thr and Tyr phosphorylation of several polypeptides in epimastigotes. Oxidative stress increases global Tyr phosphorylation by about twofold and also TcPolβ phosphorylation. TcPKC2 and TcWee570 were able to phosphorylate TcPolβ at both Ser/Thr and Tyr residues. Conclusions: Small-molecule protein kinase inhibitors can affect the phosphorylation status of TcPolβ in vivo. Since Genistein can inhibit both Ser/Thr and Tyr protein phosphorylation, and TcPKC2 and TcWee570 can phosphorylate both Ser/Thr and Tyr residues, it suggests the existence of dual protein kinases in T. cruzi. However, this possibility must be further studied. Full article

Single nucleotide polymorphisms (SNPs), as common genetic variations, can influence biological processes. Identifying these variations is crucial for recognizing high-risk subgroups, guiding preventive strategies, and enabling personalized management. Objective: This study aimed to determine the relationship between SNPs and survival, thereby identifying genetic profiles associated with increased risk. Methods: We included seropositive patients with Chagas disease who had a disease duration of >20 years and no comorbidities. DNA was extracted. A SNP panel focusing on genes involved in cardiac structure was created from the GnomAD database. Patients were followed for 8 years to assess survival. The association between SNPs and survival was evaluated, and a genetic risk score was generated. Univariate and multivariate Cox regression models assessed the association between SNPs (coded as ordinal variables) and survival time. SNPs with p < 0.05 were selected to construct a risk score, which was then assessed using Kaplan–Meier curves and median survival times. Results: A total of 182 patients were included, with 96.7% completing follow-up for a median of 5.1 years (interquartile range: 3.4–6.5). The median age was 62 years; 39.6% of patients were male, and 31% had reduced left ventricular ejection fraction. Univariate analysis showed that 3 of the 68 SNPs studied were associated with survival. Variant rs3755863 (PPARGC1A gene) was significantly associated with an increased risk of death (hazard ratio, HR = 1.94; p = 0.022). Conversely, two variants, rs7310615 (SH2B3 gene) and rs7405731 (JUP gene), showed a protective effect with significantly reduced mortality risk (HR = 0.45; p = 0.006 and HR = 0.48; p = 0.006, respectively). In multivariate analysis, rs7310615 and rs7405731 remained significantly associated with survival. A genetic risk score was constructed, assigning 0 points for homozygous wild-type, 1 point for heterozygotes, and 2 points for homozygous alternative alleles. Individual scores were calculated, and survival was estimated for each score category using Kaplan–Meier analysis and median survival times. Conclusions: Two SNPs were identified as significantly associated with survival. These findings require confirmation in larger and more diverse populations. Their validation could enable the identification of a subgroup of patients at particularly high risk. Full article

Chagas disease, caused by Trypanosoma cruzi, is maintained in nature by complex interactions among wild vertebrates and triatomine insect vectors, yet the role of many introduced hosts remains poorly resolved. Here, we assessed natural T. cruzi infection in wild European rabbits (Oryctolagus cuniculus) from central Chile, where introduced rabbits overlap ecologically with the sylvatic vector Mepraia spinolai. Eight free-ranging rabbits captured in Las Chinchillas National Reserve were evaluated using an integrative diagnostic approach combining xenodiagnosis with laboratory-reared, parasite-free M. spinolai nymphs, real-time polymerase chain reaction targeting T. cruzi satellite DNA in blood and 12–14 organs per animal, and histopathology with immunohistochemistry (anti-cruzipain) to identify tissue parasite forms. Blood molecular detection was positive in seven out of eight rabbits, while xenodiagnosis detected viable parasites in two out of seven evaluated individuals. Organ molecular screening detected T. cruzi DNA in at least one organ in all rabbits, with frequent positivity in the diaphragm, reproductive tissues, spleen, and kidney. Histopathology identified parasite forms in four out of eight animals, and immunohistochemistry confirmed hepatic amastigotes in one case. These findings provide multi-method evidence of natural infection in the sampled individuals, including evidence of parasite viability in some individuals, suggesting potential epidemiological relevance within this ecological context and possible utility for surveillance in Chilean sylvatic transmission settings. Full article

Chagas disease remains a major public health challenge and still lacks reliable serum biomarkers capable of accurately reflecting disease progression and therapeutic response. Here, we performed a quantitative label-free serum proteomic analysis in a murine model infected with two Trypanosoma cruzi strains exhibiting contrasting sensitivity to benznidazole (Be-78, sensitive; VL-10, resistant), evaluated during both acute and chronic phases, in the presence or absence of treatment. Distinct proteomic signatures were observed across strains, infection stages, and experimental groups, involving pathways related to complement activation, inflammatory responses, immunoglobulins, energy metabolism, and tissue remodeling. Markers of cellular injury, including LDH-A, C1q, and C6, remained predominantly elevated in mice infected with the benznidazole-resistant strain, whereas animals infected with Be-78 showed substantial proteomic normalization following treatment. In addition, structural proteins such as dystrophin, nebulin, alpha-adducin, and myosin XVIIIb clearly distinguished strain-dependent profiles of disease aggressiveness and tissue damage. Integrated analyses revealed that benznidazole efficacy is strongly influenced by the biological characteristics of the infecting strain and is directly mirrored in the serum proteome. Collectively, these findings identify promising serum biomarkers of tissue injury and therapeutic response and underscore the importance of parasite genetic variability in disease monitoring and in the development of improved diagnostic and therapeutic strategies. Full article