Specificity of serological screening tests and reference laboratory tests to diagnose gambiense human African trypanosomiasis: a prospective clinical performance study.

BACKGROUND: Serological screening tests play a crucial role to diagnose gambiense human African trypanosomiasis (gHAT). Presently, they preselect individuals for microscopic confirmation, but in future "screen and treat" strategies they will identify individuals for treatment. Variability in reported specificities, the development of new rapid diagnostic tests (RDT) and the hypothesis that malaria infection may decrease RDT specificity led us to evaluate the specificity of 5 gHAT screening tests. METHODS: During active screening, venous blood samples from 1095 individuals from Côte d'Ivoire and Guinea were tested consecutively with commercial (CATT, HAT Sero-K-SeT, Abbott Bioline HAT 2.0) and prototype (DCN HAT RDT, HAT Sero-K-SeT 2.0) gHAT screening tests and with a malaria RDT. Individuals with ≥ 1 positive gHAT screening test underwent microscopy and further immunological (trypanolysis with T.b. gambiense LiTat 1.3, 1.5 and 1.6; indirect ELISA/T.b. gambiense; T.b. gambiense inhibition ELISA with T.b. gambiense LiTat 1.3 and 1.5 VSG) and molecular reference laboratory tests (PCR TBRN3, 18S and TgsGP; SHERLOCK 18S Tids, 7SL Zoon, and TgsGP; Trypanozoon S2-RT-qPCR 18S2, 177T, GPI-PLC and TgsGP in multiplex; RT-qPCR DT8, DT9 and TgsGP in multiplex). Microscopic trypanosome detection confirmed gHAT, while other individuals were considered gHAT free. Differences in fractions between groups were assessed by Chi square and differences in specificity between 2 tests on the same individuals by McNemar. RESULTS: One gHAT case was diagnosed. Overall test specificities (n = 1094) were: CATT 98.9% (95% CI: 98.1-99.4%); HAT Sero-K-SeT 86.7% (95% CI: 84.5-88.5%); Bioline HAT 2.0 82.1% (95% CI: 79.7-84.2%); DCN HAT RDT 78.2% (95% CI: 75.7-80.6%); and HAT Sero-K-SeT 2.0 78.4% (95% CI: 75.9-80.8%). In malaria positives, gHAT screening tests appeared less specific, but the difference was significant only in Guinea for Abbott Bioline HAT 2.0 (P = 0.03) and HAT Sero-K-Set 2.0 (P = 0.0006). The specificities of immunological and molecular laboratory tests in gHAT seropositives were 98.7-100% (n = 399) and 93.0-100% (n = 302), respectively. Among 44 reference laboratory test positives, only the confirmed gHAT patient and one screening test seropositive combined immunological and molecular reference laboratory test positivity. CONCLUSIONS: Although a minor effect of malaria cannot be excluded, gHAT RDT specificities are far below the 95% minimal specificity stipulated by the WHO target product profile for a simple diagnostic tool to identify individuals eligible for treatment. Unless specificity is improved, an RDT-based "screen and treat" strategy would result in massive overtreatment. In view of their inconsistent results, additional comparative evaluations of the diagnostic performance of reference laboratory tests are indicated for better identifying, among screening test positives, those at increased suspicion for gHAT. TRIAL REGISTRATION: The trial was retrospectively registered under NCT05466630 in clinicaltrials.gov on July 15 2022.

Discovery of 1,3,4-Oxadiazole Derivatives as Broad-Spectrum Antiparasitic Agents.

Vector-borne parasitic diseases (VBPDs) pose a significant threat to public health on a global scale. Collectively, Human African Trypanosomiasis (HAT), Leishmaniasis, and Malaria threaten millions of people, particularly in developing countries. Climate change might alter the transmission and spread of VBPDs, leading to a global burden of these diseases. Thus, novel agents are urgently needed to expand therapeutic options and limit the spread of drug-resistant parasites. Herein, we report the development of broad-spectrum antiparasitic agents by screening a known library of antileishmanial and antimalarial compounds toward Trypanosoma brucei (T. brucei) and identifying a 1,3,4-oxadiazole derivative (19) as anti-T. brucei hit with predicted blood-brain barrier permeability. Subsequently, extensive structure-activity-relationship studies around the lipophilic tail of 19 led to a potent antitrypanosomal and antimalarial compound (27), with moderate potency also toward Leishmania infantum (L. infantum) and Leishmania tropica. In addition, we discovered a pan-active antiparasitic molecule (24), showing low-micromolar IC50s toward T. brucei and Leishmania spp. promastigotes and amastigotes, and nanomolar IC50 against Plasmodium falciparum, together with high selectivity for the parasites over mammalian cells (THP-1). Early ADME-toxicity assays were used to assess the safety profile of the compounds. Overall, we characterized 24 and 27, bearing the 1,3,4-oxadiazole privileged scaffold, as broad-spectrum low-toxicity agents for the treatment of VBPDs. An alkyne-substituted chemical probe (30) was synthesized and will be utilized in proteomics experiments aimed at deconvoluting the mechanism of action in the T. brucei parasite.

From pole to pole, life-long research of sleep in extreme environments.

In November 1965, Michel Jouvet accepted me into his laboratory in Lyon as a medical student at a time when sleep research was an adventure. After 4 years of investigations in cats, I obtained my medical doctorate. Being a military physician, I was posted to Antarctica for wintering over and was initiated by Jean Rivolier into the psychology of small isolated human groups. I recorded 180 polysomnographic (PSG) nights in eight of my companions. This was my first contribution to research on human sleep under extreme environments and conditions. I then entered René Hénane's military thermophysiology laboratory, where I analyzed thermal exchanges during human sleep in the heat. Back to the cold, I spent 2 years in Canada and analyzed sleep during the Arctic winter under the direction of Manny W. Radomski, who headed the Defense and Civil Institute of Environmental Medicine and judged my PhD dissertation along with my first two mentors. Throughout my career, I worked in collaboration with Manny Radomski under the auspices of the Franco-Canadian Accord for Defence Research. We studied sleep and exercise, sleep deprivation, and recovery with and without chemical help. He also gave me support during several investigations in Africa. There, I studied normal sleep under various tropical climates (warm and dry in Niger, warm and humid in Côte d'Ivoire and Congo, temperate mid-mountain in Angola). I determined that human African trypanosomiasis, the ravaging sleeping sickness or tsetse disease, is not a hypersomnia, but a disorder of circadian rhythms, notably in the sleep-wake cycle.

Discovery of Strong 3-Nitro-2-Phenyl-2H-Chromene Analogues as Antitrypanosomal Agents and Inhibitors of Trypanosoma cruzi Glucokinase.

Chagas disease is one of the world's neglected tropical diseases, caused by the human pathogenic protozoan parasite Trypanosoma cruzi. There is currently a lack of effective and tolerable clinically available therapeutics to treat this life-threatening illness and the discovery of modern alternative options is an urgent matter. T. cruzi glucokinase (TcGlcK) is a potential drug target because its product, d-glucose-6-phosphate, serves as a key metabolite in the pentose phosphate pathway, glycolysis, and gluconeogenesis. In 2019, we identified a novel cluster of TcGlcK inhibitors that also exhibited anti-T. cruzi efficacy called the 3-nitro-2-phenyl-2H-chromene analogues. This was achieved by performing a target-based high-throughput screening (HTS) campaign of 13,040 compounds. The selection criteria were based on first determining which compounds strongly inhibited TcGlcK in a primary screen, followed by establishing on-target confirmed hits from a confirmatory assay. Compounds that exhibited notable in vitro trypanocidal activity over the T. cruzi infective form (trypomastigotes and intracellular amastigotes) co-cultured in NIH-3T3 mammalian host cells, as well as having revealed low NIH-3T3 cytotoxicity, were further considered. Compounds GLK2-003 and GLK2-004 were determined to inhibit TcGlcK quite well with IC50 values of 6.1 µM and 4.8 µM, respectively. Illuminated by these findings, we herein screened a small compound library consisting of thirteen commercially available 3-nitro-2-phenyl-2H-chromene analogues, two of which were GLK2-003 and GLK2-004 (compounds 1 and 9, respectively). Twelve of these compounds had a one-point change from the chemical structure of GLK2-003. The analogues were run through a similar primary screening and confirmatory assay protocol to our previous HTS campaign. Subsequently, three in vitro biological assays were performed where compounds were screened against (a) T. cruzi (Tulahuen strain) infective form co-cultured within NIH-3T3 cells, (b) T. brucei brucei (427 strain) bloodstream form, and (c) NIH-3T3 host cells alone. We report on the TcGlcK inhibitor constant determinations, mode of enzyme inhibition, in vitro antitrypanosomal IC50 determinations, and an assessment of structure-activity relationships. Our results reveal that the 3-nitro-2-phenyl-2H-chromene scaffold holds promise and can be further optimized for both Chagas disease and human African trypanosomiasis early-stage drug discovery research.

Insights to Design New Drugs against Human African Trypanosomiasis Targeting Rhodesain using Covalent Docking, Molecular Dynamics Simulations, and MM-PBSA Calculations.

BACKGROUND: Neglected tropical diseases (NTDs) are parasitic and bacterial diseases that affect approximately 149 countries, mainly the poor population without basic sanitation. Among these, African Human Trypanosomiasis (HAT), known as sleeping sickness, shows alarming data, with treatment based on suramin and pentamidine in the initial phase and melarsoprol and eflornithine in the chronic phase. Thus, to discover new drugs, several studies point to rhodesain as a promising drug target due to the function of protein degradation and intracellular transport of proteins between the insect and host cells and is present in all cycle phases of the parasite. METHODOLOGY: Here, based on the previous studies by Nascimento et al. (2021) that show the main rhodesain inhibitors development in the last decade, molecular docking and dynamics were applied in these inhibitors datasets to reveal crucial information that can be into drug design. Thus, conventional and covalent docking was employed and highlighted the presence of Michael acceptors in the ligands in a peptidomimetics scaffold, and interaction with Gly19, Gly23, Gly65, Asp161, and Trp184 is essential to the inhibiting activity. RESULTS: Also, our findings using MD simulations and MM-PBSA calculations confirmed Gly19, Gly23, Gly65, Asp161, and Trp184, showing high binding energy (ΔGbind between -72.782 to -124.477 kJ.mol-1). In addition, Van der Waals interactions have a better contribution (-140,930 to -96,988 kJ.mol-1) than electrostatic forces (-43,270 to -6,854 kJ.mol-1), indicating Van der Waals interactions are the leading forces in forming and maintaining ligand-rhodesain complexes. CONCLUSION: Furthermore, the Dynamic Cross-Correlation Maps (DCCM) show more correlated movements for all complexes than the free rhodesain and strong interactions in the regions of the aforementioned residues. Principal Component Analysis (PCA) demonstrates complex stability corroborating with RMSF and RMSD. This study can provide valuable insights that can guide researchers worldwide to discover a new promising drug against HAT.

Reemergence of Human African Trypanosomiasis Caused by Trypanosoma brucei rhodesiense, Ethiopia.

We report 4 cases of human African trypanosomiasis that occurred in Ethiopia in 2022, thirty years after the last previously reported case in the country. Two of 4 patients died before medicine became available. We identified the infecting parasite as Trypanosoma brucei rhodesiense. Those cases imply human African trypanosomiasis has reemerged.

Repurposing Know-how for Drug Development: Case Studies from the Swiss Tropical and Public Health Institute.

In pursuing novel therapeutic solutions, drug discovery and development rely on efficiently utilising existing knowledge and resources. Repurposing know-how, a strategy that capitalises on previously acquired information and expertise, has emerged as a powerful approach to accelerate drug discovery and development processes, often at a fraction of the costs of de novo developments. For 80 years, collaborating within a network of partnerships, the Swiss Tropical and Public Health Institute (Swiss TPH) has been working along a value chain from innovation to validation and application to combat poverty-related diseases. This article presents an overview of selected know-how repurposing initiatives conducted at Swiss TPH with a particular emphasis on the exploration of drug development pathways in the context of neglected tropical diseases and other infectious diseases of poverty, such as schistosomiasis, malaria and human African trypanosomiasis.

The Evolving Spectrum of Human African Trypanosomiasis.

Human African trypanosomiasis (HAT), or sleeping sickness, continues to be a major threat to human health in 36 countries throughout sub-Saharan Africa with up to 60 million people at risk. Over the last decade there have been several advances in this area, some of which are discussed in this overview. Due to the concerted efforts of several bodies, including better identification and treatment of cases and improved tsetse fly vector control, the number of cases of HAT has declined dramatically. The clinical heterogeneity of HAT has also been increasingly recognised and the disease, while usually fatal if untreated or inadequately treated, does not always have a uniformly fatal outcome. Improved methods of HAT diagnosis have now been developed including Rapid Diagnostic Tests (RDTs). Novel drug treatment of HAT has also been developed, notably NECT for late- stage T.b.gambiense, oral fexinidazole for early and the early component of the late-stage of T.b.gambiense, and the new oral compounds of the oxaborole group which have shown considerable promise in field trials. Advances in HAT neuropathogenesis have been steady though largely incremental, with a particular focus on the role of the BBB in parasite entry into the Central Nervous System (CNS), and the relevant importance of both innate and adaptive immunity. While the WHO goal of elimination of HAT as a public health problem by 2020 has probably been achieved, it remains to be seen whether the second more ambitious goal of interruption of transmission of HAT by 2030 will be attained.

Synthesis and characterization of I-BET151 derivatives for use in identifying protein targets in the African trypanosome.

Trypanosoma brucei, the causative agent of Human African Trypanosomiasis (HAT) and animal trypanosomiases, cycles between a bloodstream form in mammals and a procyclic form in the gut of its insect vector. We previously discovered that the human bromodomain inhibitor I-BET151 causes transcriptome changes that resemble the transition from the bloodstream to the procyclic form. In particular, I-BET151 induces replacement of variant surface glycoprotein (VSG) with procyclin protein. While modest binding of I-BET151 to TbBdf2 and TbBdf3 has been demonstrated, it is unknown whether I-BET151 binds to other identified T. brucei bromodomain proteins and/or other targets. To identify target(s) in T. brucei, we have synthesized I-BET151 derivatives maintaining the key pharmacophoric elements with functionality useful for chemoproteomic approaches. We identified compounds that are potent in inducing expression of procyclin, delineating a strategy towards the design of drugs against HAT and other trypanosomiases. Furthermore, these derivatives represent useful chemical probes to elucidate the molecular mechanism underlying I-BET151-induced differentiation.

In Silico and In Vitro Search for Dual Inhibitors of the Trypanosoma brucei and Leishmania major Pteridine Reductase 1 and Dihydrofolate Reductase.

The parasites Trypanosoma brucei (Tb) and Leishmania major (Lm) cause the tropical diseases sleeping sickness, nagana, and cutaneous leishmaniasis. Every year, millions of humans, as well as animals, living in tropical to subtropical climates fall victim to these illnesses' health threats. The parasites' frequent drug resistance and widely spread natural reservoirs heavily impede disease prevention and treatment. Due to pteridine auxotrophy, trypanosomatid parasites have developed a peculiar enzyme system consisting of dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase 1 (PTR1) to support cell survival. Extending our previous studies, we conducted a comparative study of the T. brucei (TbDHFR, TbPTR1) and L. major (LmDHFR, LmPTR1) enzymes to identify lead structures with a dual inhibitory effect. A pharmacophore-based in silico screening of three natural product databases (approximately 4880 compounds) was performed to preselect possible inhibitors. Building on the in silico results, the inhibitory potential of promising compounds was verified in vitro against the recombinant DHFR and PTR1 of both parasites using spectrophotometric enzyme assays. Twelve compounds were identified as dual inhibitors against the Tb enzymes (0.2 µM < IC50 < 85.1 µM) and ten against the respective Lm enzymes (0.6 µM < IC50 < 84.5 µM). These highly promising results may represent the starting point for the future development of new leads and drugs utilizing the trypanosomatid pteridine metabolism as a target.

Host-Derived Extracellular Vesicles in Blood and Tissue Human Protozoan Infections.

Blood and tissue protozoan infections are responsible for an enormous burden in tropical and subtropical regions, even though they can also affect people living in high-income countries, mainly as a consequence of migration and travel. These pathologies are responsible for heavy socio-economic issues in endemic countries, where the lack of proper therapeutic interventions and effective vaccine strategies is still hampering their control. Moreover, the pathophysiological mechanisms associated with the establishment, progression and outcome of these infectious diseases are yet to be fully described. Among all the players, extracellular vesicles (EVs) have raised significant interest during the last decades due to their capacity to modulate inter-parasite and host-parasite interactions. In the present manuscript, we will review the state of the art of circulating host-derived EVs in clinical samples or in experimental models of human blood and tissue protozoan diseases (i.e., malaria, leishmaniasis, Chagas disease, human African trypanosomiasis and toxoplasmosis) to gain novel insights into the mechanisms of pathology underlying these conditions and to identify novel potential diagnostic markers.

In silico identification of α-bisabolol and letestuianin C as potential inhibitors of Trypanosoma brucei trypanothione reductase.

Despite the recent advances in drug research, finding a safe, effective, and easy to use chemotherapy for human African trypanosomiasis (HAT) remains a challenging task. Trypanosomatids have developed resistance mechanisms towards melarsoprol (the current drug of choice), and the fact that it is poisonous is problematic. Therefore, a search for alternative therapeutics against the parasite is urgently needed. Natural products offer potential for drug discovery, but little or nothing is known about the target of inhibition or possible mode of inhibition. Therefore, this study aimed to use molecular docking and molecular dynamics simulations to evaluate 30 antitrypanosomal natural products as potential inhibitors of trypanothione reductase, a key protein necessary for the survival of the Trypanosoma brucei. The study also assessed the pharmacokinetic properties of the most promising compounds. Of the compounds evaluated, α-bisabolol, letestuianin C, waltherione, and mexicanin E were found to bind at the active site of TR and interact with Met115, Tyr112, and Trp23, which are essential for enzyme functioning. Molecular dynamic simulations revealed the sustained binding of α-bisabolol and letestuianin C throughout the simulation period, potentially obstructing the binding of the substrate (T[S]2) and impeding catalysis. The binding of these compounds to TR led to the presence of solvent molecules in the enzyme's active site, and this could potentially lead to protein aggregation. Furthermore, α-bisabolol and letestuianin C exhibited promising safety profiles. Consequently, α-bisabolol and letestuianin C have been shown to be viable candidates for targeting trypanothione reductase in the fight against human African trypanosomiasis.Communicated by Ramaswamy H. Sarma.

[Towards elimination of human African trypanosomiasis]. / Vers l'élimination de la maladie du sommeil.

Human African Trypanosomiasis (HAT) is caused by Trypanosoma brucei which is transmitted by the tsetse fly insect vector (Glossina spp). It is one of the 20 Neglected Tropical Diseases (NTD) listed by the WHO. These diseases affect the poorest and most vulnerable communities, for which the WHO has established a dedicated 2021-2030 roadmap. At the time of Alphonse Laveran, HAT devastated the African continent. In the 1960s, the disease was nearly under control, but it strongly re-emerged in the 1990s. A coordinated effort of all stakeholders, with national control programs as the main actors, a strong contribution of research and important donations by the private sector, allowed to decrease the HAT burden significantly. Since 2018, less than 1000 cases are detected annually. We here review new diagnostics, treatments and vector control tools that have been implemented jointly and successfully in several endemic countries.The next key challenge will be to sustain the gains. Newly emerging research questions include long-term carriage of trypanosomes and adaptation of tools to low prevalence contexts. Challenges out of the research area comprise the continued need of funding, maintenance of dedicated human resources, and the key question of access. Sustainable elimination as "interruption of transmission", which is the 2030 NTD roadmap target, can be reached, if these challenges are solved. We stress the importance of continuing to combine the efforts in the fight against the disease, because sustainable elimination of HAT is the best long-term prevention strategy against re-emergence. As such, HAT elimination can serve as an example for other infectious diseases.

Current Prospects of Saponins as Promising Anti-Trypanosoma brucei Compounds: Insight into the Mechanisms of Action.

BACKGROUND: Human African trypanosomiasis (HAT) is a parasitic infection that may lead to death if left untreated. This disease is caused by a protozoan parasite of the genus Trypanosoma and is transmitted to humans through tsetse fly bites. The disease is widespread across Sub-Saharan Africa, with 70% of cases in recent reports in the Democratic Republic of the Congo and an average of less than 1000 cases are declared annually. Since there is no appropriate treatment for HAT, steroidal and triterpenoid saponins have been reported to be effective in in vitro studies and might serve as scaffolds for the discovery of new treatments against this disease. AIM OF THE STUDY: The present study aimed to summarize up-to-date information on the anti-Trypanosoma brucei activity of steroidal and triterpenoid saponins. The mechanisms of action of in vitro bioactive compounds were also discussed. METHODS: Information on the anti-Trypanosoma brucei activity of plant saponins was obtained from published articles, dissertations, theses, and textbooks through a variety of libraries and electronic databases. RESULTS: There has been incredible progress in the identification of steroidal and triterpenoid saponins with pronounced in vitro activity against Trypanosoma brucei. Indeed, more than forty saponins were identified as having anti-T. brucei effect with activity ranging from moderate to highly active. The mechanisms of action of most of these saponins included DNA damage, cell cycle arrest, induction of apoptosis through downregulation of bcl-2 and MDM2, and upregulation of Bax and Bak, among others. CONCLUSION: Referring to in vitro studies, plant saponins have shown anti-Trypanosoma brucei activity; however, more cytotoxic and in vivo studies and detailed mechanisms of action of the bioactive saponins should be further considered.

Structure-Activity Relationships, Tolerability and Efficacy of Microtubule-Active 1,2,4-Triazolo[1,5-a]pyrimidines as Potential Candidates to Treat Human African Trypanosomiasis.

Tubulin and microtubules (MTs) are potential protein targets to treat parasitic infections and our previous studies have shown that the triazolopyrimidine (TPD) class of MT-active compounds hold promise as antitrypanosomal agents. MT-targeting TPDs include structurally related but functionally diverse congeners that interact with mammalian tubulin at either one or two distinct interfacial binding sites; namely, the seventh and vinca sites, which are found within or between α,ß-tubulin heterodimers, respectively. Evaluation of the activity of 123 TPD congeners against cultured Trypanosoma brucei enabled a robust quantitative structure-activity relationship (QSAR) model and the prioritization of two congeners for in vivo pharmacokinetics (PK), tolerability and efficacy studies. Treatment of T. brucei-infected mice with tolerable doses of TPDs significantly decreased blood parasitemia within 24 h. Further, two once-weekly doses at 10 mg/kg of a candidate TPD significantly extended the survival of infected mice relative to infected animals treated with vehicle. Further optimization of dosing and/or the dosing schedule of these CNS-active TPDs may provide alternative treatments for human African trypanosomiasis.

Performance of clinical signs and symptoms, rapid and reference laboratory diagnostic tests for diagnosis of human African trypanosomiasis by passive screening in Guinea: a prospective diagnostic accuracy study.

BACKGROUND: Passive diagnosis of human African trypanosomiasis (HAT) at the health facility level is a major component of HAT control in Guinea. We examined which clinical signs and symptoms are associated with HAT, and assessed the performance of selected clinical presentations, of rapid diagnostic tests (RDT), and of reference laboratory tests on dried blood spots (DBS) for diagnosing HAT in Guinea. METHOD: The study took place in 14 health facilities in Guinea, where 2345 clinical suspects were tested with RDTs (HAT Sero-K-Set, rHAT Sero-Strip, and SD Bioline HAT). Seropositives underwent parasitological examination (reference test) to confirm HAT and their DBS were tested in indirect enzyme-linked immunoassay (ELISA)/Trypanosoma brucei gambiense, trypanolysis, Loopamp Trypanosoma brucei Detection kit (LAMP) and m18S quantitative PCR (qPCR). Multivariable regression analysis assessed association of clinical presentation with HAT. Sensitivity, specificity, positive and negative predictive values of key clinical presentations, of the RDTs and of the DBS tests for HAT diagnosis were determined. RESULTS: The HAT prevalence, as confirmed parasitologically, was 2.0% (48/2345, 95% CI: 1.5-2.7%). Odds ratios (OR) for HAT were increased for participants with swollen lymph nodes (OR = 96.7, 95% CI: 20.7-452.0), important weight loss (OR = 20.4, 95% CI: 7.05-58.9), severe itching (OR = 45.9, 95% CI: 7.3-288.7) or motor disorders (OR = 4.5, 95% CI: 0.89-22.5). Presence of at least one of these clinical presentations was 75.6% (95% CI: 73.8-77.4%) specific and 97.9% (95% CI: 88.9-99.9%) sensitive for HAT. HAT Sero-K-Set, rHAT Sero-Strip, and SD Bioline HAT were respectively 97.5% (95% CI: 96.8-98.1%), 99.4% (95% CI: 99.0-99.7%) and 97.9% (95% CI: 97.2-98.4%) specific, and 100% (95% CI: 92.5-100.0%), 59.6% (95% CI: 44.3-73.3%) and 93.8% (95% CI: 82.8-98.7%) sensitive for HAT. The RDT's positive and negative predictive values ranged from 45.2-66.7% and 99.2-100% respectively. All DBS tests had specificities ≥ 92.9%. While LAMP and m18S qPCR sensitivities were below 50%, trypanolysis and ELISA/T.b. gambiense had sensitivities of 85.3% (95% CI: 68.9-95.0%) and 67.6% (95% CI: 49.5-82.6%). CONCLUSIONS: Presence of swollen lymph nodes, important weight loss, severe itching or motor disorders are simple but accurate clinical criteria for HAT referral in HAT endemic areas in Guinea. Diagnostic performances of HAT Sero-K-Set and SD Bioline HAT are sufficient for referring positives to microscopy. Trypanolysis on DBS may discriminate HAT patients from false RDT positives. Trial registration The trial was registered under NCT03356665 in clinicaltrials.gov (November 29, 2017, retrospectively registered https://clinicaltrials.gov/ct2/show/NCT03356665 ).

Emerging compounds and therapeutic strategies to treat infections from Trypanosoma brucei: an overhaul of the last 5-years patents.

INTRODUCTION: Human African Trypanosomiasis is a neglected disease caused by infection from parasites belonging to the Trypanosoma brucei species. Only six drugs are currently available and employed depending on the stage of the infection: pentamidine, suramin, melarsoprol, eflornithine, nifurtimox, and fexinidazole. Joint research projects were launched in an attempt to find new therapeutic options for this severe and often lethal disease. AREAS COVERED: After a brief description of the recent literature on the parasite and the disease, we searched for patents dealing with the proposal of new antitrypanosomiasis agents and, following the PRISMA guidelines, we filtered the results to those published from 2018 onwards returning suitable entries, which represent the contemporary landscape of compounds/strategies against Trypanosoma brucei. In addition, some relevant publications from the overall scientific literature were also discussed. EXPERT OPINION: This review comprehensively covers and analyzes the most recent advances not only in the discovery of new inhibitors and their structure-activity relationships but also in the assessment of innovative biological targets opening new scenarios in the MedChem field. Finally, also new vaccines and formulations recently patented were described. However, natural and synthetic compounds were analyzed in terms of inhibitory activity and selective toxicity against human cells.

Structural Insight into Privileged Heterocycles as Anti-Trypanosoma cruzi and brucei Agents.

Trypanosomiasis is caused by parasitic protozoan trypanosomes in vertebrates. T. cruzi and T. brucei are causative agents of Chagas disease (CD) and Human African Trypanosomiasis (HAT), respectively. These life-threatening diseases are a serious threat to public health, with considerable incidence in sub-Saharan African and continental Latin America countries. Although WHO validated mitigated number of HAT cases in Togo (June 2020) and Cote d'Ivoire (December 2020), serious efforts need to be performed for the elimination of the disease. Antigenic variation of trypanosomal parasites provides a major bottleneck for developing effective vaccines. In the absence of human vaccines or chemoprophylaxis, the control of trypanosomatid infections may be envisaged through the eradication of vectors, management of animal reservoirs, and chemotherapy. A small number of chemical agents are currently available for antitrypanosomal treatments, and most of them are associated with toxicity, lack of efficacy, and non-oral route of administration. Given the restricted applicability of current medications, numerous efforts have been made for the synthesis and biological evaluation of heterocyclic scaffolds as antitrypanosomal candidates. In light of the above considerations, we were prompted to describe chemical diversity within privileged 5- membered heterocycles (imidazoles, thiazoles, triazoles and tetrazoles) as antitrypanosomal agents. The main purpose of the study was to throw light on the structure-activity relationship (SAR) of the relevant structures. To capture the recent structural diversity within reported cases, small molecules that belonged to the recent 7-year period (2015-2021) have been discussed. The available medications have also been briefly reviewed.

Retrospective Review of Chromane Analogues as Anti-protozoal Leads: A Decade's Worth of Evolution.

Tropical, vector-borne, and neglected diseases with a limited number of medication therapies include Leishmaniasis, Malaria, Chagas and Human African Trypanosomiasis (HAT). Chromones are a large class of heterocyclic compounds with significant applications. This heterocycle has long aroused the interest of scientists and the general public from biosynthetic and synthetic points of view owing to its interesting pharmacological activities. Chromones and their hybrids and isomeric forms proved to be an exciting scaffold to investigate these diseases. The in vitro activities of Chromone, Chromane, and a panel of other related benzopyran class compounds against Trypanosoma brucei rhodesiense, Trypanosoma brucei gambiense, Trypanosoma cruzi, and numerous Leishmanial and Malarial species were investigated in our previous studies. The current article briefly describes the neglected diseases and the current treatment. This review aims to attempt to find better alternatives by scrutinizing natural and synthetic derivatives for which chromones and their analogues were discovered to be a new and highly effective scaffold for the treatment of neglected diseases, including compounds with dual activity or activity against multiple parasites. Additionally, the efficacy of other new scaffolds was also thoroughly examined. This article also discusses prospects for identifying more unique targets for the disease, focusing on flavonoids as drug molecules that are less cytotoxic and high antiprotozoal potential. It also emphasizes the changes that can be made while searching for potential therapies-comparing existing treatments against protozoal diseases and the advantages of the newer chromone analogues over them. Finally, the structure- activity relationship at each atom of the chromone has also been highlighted.