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Advances in Experimental Medicine and... Jun 2024According to the World Health Organization vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually. Vectors...
According to the World Health Organization vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually. Vectors are organisms that are able to transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are hematophagous insects, which ingest the pathogen from an infected host during a blood meal, and later transmit it into a new host. Malaria, dengue, African trypanosomiasis, yellow fever, leishmaniasis, Chagas disease, and many others are examples of diseases transmitted by insects.Both the diet and the infection with pathogens trigger changes in many metabolic pathways, including lipid metabolism, compared to other insects. Blood contains mostly proteins and is very poor in lipids and carbohydrates. Thus, hematophagous insects attempt to efficiently digest and absorb diet lipids and also rely on a large de novo lipid biosynthesis based on utilization of proteins and carbohydrates as carbon source. Blood meal triggers essential physiological processes as molting, excretion, and oogenesis; therefore, lipid metabolism and utilization of lipid storage should be finely synchronized and regulated regarding that, in order to provide the necessary energy source for these events. Also, pathogens have evolved mechanisms to hijack essential lipids from the insect host by interfering in the biosynthesis, catabolism, and transport of lipids, which pose challenges to reproduction, survival, fitness, and other insect traits.In this chapter, we have tried to collect and highlight the current knowledge and recent discoveries on the metabolism of lipids in insect vectors of diseases related to the hematophagous diet and pathogen infection.
PubMed: 38954247
DOI: 10.1007/5584_2024_811 -
PLoS Neglected Tropical Diseases Jul 2024The scarcity of reliable devices for diagnosis of Animal African trypanosomiasis (AAT) presents a limitation to control of the disease. Existing high-sensitivity...
The scarcity of reliable devices for diagnosis of Animal African trypanosomiasis (AAT) presents a limitation to control of the disease. Existing high-sensitivity technologies such as PCR are costly, laborious, time-consuming, complex, and require skilled personnel. Hence, utilisation of most diagnostics for AAT is impracticable in rural areas, where the disease occurs. A more accessible point-of-care test (POCT) capable of detecting cryptic active infection, without relying on expensive equipment, would facilitate AAT detection. In turn, early management, would reduce disease incidence and severity. Today, several ongoing research projects aim at modifying complex immunoassays into POCTs. In this context, we report the development of an antigen (Ag) detection sandwich ELISA prototype for diagnosis of T. congolense infections, which is comprised of nanobody (Nb) and monoclonal antibody (mAb) reagents. The Nb474H used here, originated from a past study. Briefly, the Nb was engineered starting from mRNA of peripheral blood lymphocytes of an alpaca immunized with soluble lysate of Trypanosoma congolense (TC13). T. congolense glycosomal fructose-1,6-bisphosphate aldolase (TcoALD) was discovered as the cognate Ag of Nb474H. In this study, splenocytes were harvested from a mouse immunized with recombinant TcoALD and fused with NS01 cells to generate a hybridoma library. Random screening of the library on TcoALD retrieved a lone binder, designated IgM8A2. Using Nb474H as Ag-capture reagent in combination with the IgM8A2 monoclonal antibody Ag-detection reagent resulted in a tool that effectively detects native TcoALD released during infection by T. congolense parasites. Hitherto, development of POCT for detection of active trypanosome infection is elusive. The Nanobody/Monoclonal Antibody (Nb/mAb) "hybrid" sandwich technology offers prospects for exploration, using the unique specificity of Nb as a key determinant in Ag capturing, while using the versatility of monoclonal Ab to adapt to various detection conditions.
PubMed: 38950072
DOI: 10.1371/journal.pntd.0012294 -
Current Tropical Medicine Reports Dec 2023Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a vector-borne parasitic neglected tropical disease (NTD) endemic in sub-Saharan Africa. This...
PURPOSE OF REVIEW
Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a vector-borne parasitic neglected tropical disease (NTD) endemic in sub-Saharan Africa. This review aims to enhance our understanding of HAT and provide valuable insights to combat this significant public health issue by synthesizing the latest research and evidence.
RECENT FINDINGS
HAT has reached a historical < 1000 cases in 2018. In patients without neurologic symptoms and signs, the likelihood of a severe meningoencephalitic stage is deemed low, obviating the need for a lumbar puncture to guide treatment decisions using fexinidazole.
SUMMARY
Both forms of the disease, gambiense HAT (gHAT) and rhodesiense HAT (rHAT), have specific epidemiology, risk factors, diagnosis, and treatment. Disease management still requires a high index of suspicion, infectious disease expertise, and specialized medical care. Essential stakeholders in health policy are critical to accomplishing the elimination goals of the NTD roadmap for 2021-2030.
PubMed: 38939748
DOI: 10.1007/s40475-023-00304-w -
QJM : Monthly Journal of the... Jun 2024
Review
Topics: Humans; Trypanosomiasis, African; Trypanocidal Agents
PubMed: 38917478
DOI: 10.1093/qjmed/hcae106 -
PLoS Neglected Tropical Diseases Jun 2024Yaws, caused by Treponema pallidum ssp. pertenue, remains a significant public health concern in tropical regions of West Africa and the South Pacific, primarily...
Yaws, caused by Treponema pallidum ssp. pertenue, remains a significant public health concern in tropical regions of West Africa and the South Pacific, primarily affecting children in remote areas with limited access to hygiene and sanitation. In this study, conducted in three endemic countries of West Africa where yaws remains a significant public health concern (Ghana, Cameroon, and Côte d'Ivoire), we aimed to assess the knowledge, attitudes, and practices related to yaws among community members, community health workers (CHWs), and traditional healers. The study revealed variations in the perception of causes of yaws among community members: the majority or participants in Ghana attributed yaws to germs (60.2%); in Cameroon the most reported form of transmission was contact with or drinking infected water sources (44.6%); and in Côte d'Ivoire both of these answers were also the most prevalent (60.3% germs and 93.% water sources). A substantial proportion of participants in Côte d'Ivoire also associated yaws with witchcraft and divine punishment (44.8%). Only a small proportion of individuals in Ghana and Côte d'Ivoire correctly identified contact with an infected person as a form of transmission (11.9% and 20.7%, respectively) and less than half in Cameroon (42.6%), although more than 98% of all participants reported avoidance behaviours towards yaws infected people due to fear of getting infected. Most participants expressed a preference for seeking care at hospitals (49.2%, 60.6%, 86.2%) or health care professionals including doctors and nurses (58.5%, 41,5% and 17.2%) if they were diagnosed with yaws, although a quarter of participants in Côte d'Ivoire also sought support from traditional healers. The CHWs interviewed were generally well-trained on yaws causes and treatment options, although they often reported low availability of treatment and diagnostic tests for yaws. Our findings underscore the need for community education, awareness campaigns, ongoing CHW training, and improved access to yaws treatment and diagnostic resources. The data also suggest that collaboration with traditional healers, who usually hold a highly esteemed position in the society, such as giving training on yaws causes and transmission or exchanging knowledge on treatment options, could be beneficial in certain regions, particularly in Côte d'Ivoire.
PubMed: 38900827
DOI: 10.1371/journal.pntd.0012224 -
Journal of Visualized Experiments : JoVE May 2024To control and decrease the public health impact of human protozoan diseases such as Chagas disease, leishmaniasis, and human African trypanosomiasis, expediting the...
To control and decrease the public health impact of human protozoan diseases such as Chagas disease, leishmaniasis, and human African trypanosomiasis, expediting the development of new drugs and vaccines is necessary. However, this process is filled with difficulties such as highly complex parasite biology and disease pathogenesis and, as typical for neglected tropical diseases, comparatively limited funding for research and development. Thus, in vitro and in vivo study models that can sufficiently reproduce infection and disease key features while providing rational use of resources are essential for progressing research for these conditions. One example is the in vivo bioluminescence imaging (BLI) mouse model for Chagas disease, which provides highly sensitive detection of long wavelength light generated by Trypanosoma cruzi parasites expressing luciferase. Despite this technique becoming the standard approach for drug efficacy in vivo studies, research groups might still struggle to implement it due to a lack of proper practical training on equipment handling and application of quality control procedures, even when suitable BLI equipment is readily available. Considering this scenario, this protocol aims to guide from planning experiments to data acquisition and analysis, with details that facilitate the implementation of protocols in research groups with little or no experience with BLI, either for Chagas disease or for other infectious disease mouse models.
Topics: Animals; Chagas Disease; Mice; Luminescent Measurements; Disease Models, Animal; Trypanosoma cruzi; Luciferases; Trypanocidal Agents
PubMed: 38884479
DOI: 10.3791/66740 -
Methods in Cell Biology 2024African trypanosomiases and leishmaniases are significant neglected tropical diseases (NTDs) that affect millions globally, with severe health and socio-economic...
African trypanosomiases and leishmaniases are significant neglected tropical diseases (NTDs) that affect millions globally, with severe health and socio-economic consequences, especially in endemic regions. Understanding the pathogenesis and dissemination of Trypanosoma brucei and Leishmania spp. parasites within their hosts is pivotal for the development of effective interventions. Whole-body bioluminescence and fluorescence imaging systems (BLI and FLI, respectively), are powerful tools to visualize and quantify the progression and distribution of these parasites in real-time within live animal models. By combining this technology with the engineering of stable T. brucei and Leishmania spp. strains expressing luciferase and/or fluorescent proteins, crucial aspects of the infection process including the parasites' homing, the infection dynamics, the tissue tropism, or the efficacy of experimental treatments and vaccines can be deeply investigated. This methodology allows for enhanced sensitivity and resolution, elucidating previously unrecognized infection niches and dynamics. Importantly, whole-body in vivo imaging is non-invasive, enabling for longitudinal studies during the course of an infection in the same animal, thereby aligning with the "3Rs" principle of animal research. Here, we detail a protocol for the generation of dual-reporter T. brucei and L. major, and their use to infect mice and follow the spatiotemporal dynamics of infection by in vivo imaging systems. Additionally, 3D micro-computed tomography (μCT) coupled to BLI in T. brucei-infected animals is applied to gain insights into the anatomical parasite distribution. This Chapter underscores the potential of these bioimaging modalities as indispensable tools in parasitology, paving the way for novel therapeutic strategies and deeper insights into host-parasite interactions.
Topics: Animals; Disease Models, Animal; Mice; Trypanosoma brucei brucei; Multimodal Imaging; Neglected Diseases; Trypanosomiasis, African; Luminescent Measurements
PubMed: 38880525
DOI: 10.1016/bs.mcb.2024.04.003 -
Inorganic Chemistry Jun 2024Human African trypanosomiasis (HAT, sleeping sickness) and American trypanosomiasis (Chagas disease) are endemic zoonotic diseases caused by genomically related...
Human African trypanosomiasis (HAT, sleeping sickness) and American trypanosomiasis (Chagas disease) are endemic zoonotic diseases caused by genomically related trypanosomatid protozoan parasites ( and , respectively). Just a few old drugs are available for their treatment, with most of them sharing poor safety, efficacy, and pharmacokinetic profiles. Only fexinidazole has been recently incorporated into the arsenal for the treatment of HAT. In this work, new multifunctional Ru(II) ferrocenyl compounds were rationally designed as potential agents against these pathogens by including in a single molecule 1,1'-bis(diphenylphosphino)ferrocene (dppf) and two bioactive bidentate ligands: pyridine-2-thiolato-1-oxide ligand (mpo) and polypyridyl ligands (NN). Three [Ru(mpo)(dppf)(NN)](PF) compounds and their derivatives with chloride as a counterion were synthesized and fully characterized in solid state and solution. They showed activity on bloodstream (EC = 31-160 nM) and on trypomastigotes (EC = 190-410 nM). Compounds showed the lowest EC values on when compared to the whole set of metal-based compounds previously developed by us. In addition, several of the Ru compounds showed good selectivity toward the parasites, particularly against the highly proliferative bloodstream form of . Interaction with DNA and generation of reactive oxygen species (ROS) were ruled out as potential targets and modes of action of the Ru compounds. Biochemical assays and analysis led to the insight that they are able to inhibit the NADH-dependent fumarate reductase from . One representative hit induced a mild oxidation of low molecular weight thiols in . The compounds were stable for at least 72 h in two different media and more lipophilic than both bioactive ligands, mpo and NN. An initial assessment of the therapeutic efficacy of one of the most potent and selective candidates, [Ru(mpo)(dppf)(bipy)]Cl, was performed using a murine infection model of acute African trypanosomiasis. This hit compound lacks acute toxicity when applied to animals in the dose/regimen described, but was unable to control parasite proliferation , probably because of its rapid clearance or low biodistribution in the extracellular fluids. Future studies should investigate the pharmacokinetics of this compound and involve further research to gain deeper insight into the mechanism of action of the compounds.
Topics: Ferrous Compounds; Trypanosoma cruzi; Ligands; Trypanocidal Agents; Animals; Ruthenium; Mice; Metallocenes; Trypanosoma brucei brucei; Parasitic Sensitivity Tests; Molecular Structure; Organometallic Compounds; Coordination Complexes
PubMed: 38860314
DOI: 10.1021/acs.inorgchem.4c01125 -
Medecine Tropicale Et Sante... Mar 2024Tsetse flies are obligate bloodfeeders that occur exclusively in Sub-Saharan Africa, where they are the vectors of trypanosomes causing HAT (human African...
BACKGROUND - RATIONALE
Tsetse flies are obligate bloodfeeders that occur exclusively in Sub-Saharan Africa, where they are the vectors of trypanosomes causing HAT (human African trypanosomiasis) and AAT (African animal trypanosomiasis). In Chad, tsetse flies occur only in the most southern part of the country because of its favorable bioclimatic conditions. However, despite the importance of HAT and AAT in this country, very little is known about the current tsetse distribution, in particular its northern limit, which is of key importance for the surveillance of these diseases.
MATERIAL AND METHODS - RESULTS
A total of 217 biconical traps were deployed in 2021 and 2022 from the West to the East around the formerly known northern limit, resulting in 1,024 tsetse caught belonging to three different taxa: (57%), (39%) and (4%). In addition to the information gathered on the presence/absence of each tsetse taxon, we show a strong North-South shift of the northen tsetse distribution limit as compared to the previous works from 1966 to 1996, and a growing spatial fragmentation in more and more discrete pockets of tsetse presence.
DISCUSSION - CONCLUSION
This North-South shift of the northern tsetse distribution limit in Chad is the likely consequence of the combined effect of severe draughts that affected the country, and increasing human pressure on land. This update of the tsetse northern limit will be of help to the national programmes in charge of HAT and AAT.
Topics: Chad; Tsetse Flies; Animals; Animal Distribution; Climate Change; Humans; Insect Vectors
PubMed: 38846117
DOI: 10.48327/mtsi.v4i1.2024.392 -
Bioorganic & Medicinal Chemistry Letters Sep 2024Human African trypanosomiasis, or sleeping sickness, is a neglected tropical disease caused by Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense and is...
Human African trypanosomiasis, or sleeping sickness, is a neglected tropical disease caused by Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense and is invariably fatal unless treated. Current therapies present limitations in their application, parasite resistance, or require further clinical investigation for wider use. Our work, informed by previous findings, presents novel 4-[4-(4-methylpiperazin-1-yl)phenyl]-6-arylpyrimidine derivatives with promising antitrypanosomal activity. In particular, 32 exhibits an in vitro EC value of 0.5 µM against Trypanosoma brucei rhodesiense, and analogues 29, 30 and 33 show antitrypanosomal activities in the <1 µM range. We have demonstrated that substituted 4-[4-(4-methylpiperazin-1-yl)phenyl]-6-arylpyrimidines present promising antitrypanosomal hit molecules with potential for further preclinical development.
Topics: Pyrimidines; Trypanocidal Agents; Structure-Activity Relationship; Parasitic Sensitivity Tests; Molecular Structure; Trypanosoma brucei brucei; Humans; Trypanosoma brucei rhodesiense; Dose-Response Relationship, Drug; Trypanosomiasis, African
PubMed: 38823730
DOI: 10.1016/j.bmcl.2024.129825