Leishmaniasis worldwide and global estimates of its incidence. PLoS One. 2012;7:e35671. [PMID: 22693548 PMCID: PMC3365071 DOI: 10.1371/journal.pone.0035671]

Half a century of Japanese research on two Neglected Tropical Diseases (trypanosomiasis and leishmaniasis): Overseas scientific cooperation

Trypanosoma and Leishmania species are responsible of a range of Neglected Tropical Diseases (NTDs) from disfiguring conditions to fatal processes in humans. Both genera also affect wild and domestic animals causing diseases of public health significance and high economic impact on farm economy of developing areas. Japan has been actively involved in overseas cooperation and the country has a large scientific community. However, there is no information on the scientific output of Japanese scientists and institutions on these two NTDs. To explore the Japanese contribution and its profile, we have mined Web of Science database from 1971 to 2022 the articles by Japanese scientists, scientific areas and institutions, time-related variations of these parameters, and involvement in cooperation activities with foreign scientists. Research on Trypanosoma has been present in all the studied period, with higher production, whereas Leishmania-related activities showed a delay. A steady increased of Japanese scientific output was found up to the beginning of 2000s, whereas a certain stagnation was found in the present century. Low growth rate of research output on these two NTDs by Japanese authors in the 21st century is not correlated neither to the pattern found globally nor the situation in other parasitic infections. Thus, other elements should be considered in future analysis including the actual number of scientists involved and the available funding. Reinforcement of research groups from Japanese institutions and widening the scope of collaborations, particularly with health and academic centers from endemic regions, could trigger the Japanese productivity in the research area.

Leishmaniasis in Greece: Prospects of transitioning to a One Health surveillance system

Leishmaniasis is a high burden neglected disease in the Mediterranean ecoregion, lacking surveillance attention. We aimed to provide an overview of the state of leishmaniasis surveillance in Greece, investigating the prospect of transitioning to a One Health surveillance system. We conducted a narrative review describing human and animal leishmaniasis data from Greece, including entomological findings. Through a separate review process, we describe the current leishmaniasis surveillance system pertaining to humans, animals, vectors and the environment. Additionally, we distributed likert-scale questionnaires to key informants, capturing expert-view on the necessity, existing levels and barriers of OH leishmaniasis surveillance in Greece. We identified key system strengths, weaknesses, opportunities and threats respective to a OH transition through SWOT analysis. Greece is endemic for zoonotic visceral leishmaniasis (VL) and canine leishmaniasis (CanL), displaying an increasing VL trend in recent years and high national Leishmania seroprevalence rates in dogs (range: 13.8-23.4 %). Mandatory leishmaniasis notification in humans and animals, human case-based investigations, and active case finding activities in stray dogs, comprise valuable system components of high OH operational relevance. Conversely, the existing CanL surveillance governance and the lack of systematic entomological surveillance constitute important drawbacks. Moreover, the current context of public health and animal health financial constraints in Greece may impede a strategic OH transition in leishmaniasis surveillance. On the contrary, Greece's OH experience in West Nile Virus surveillance in conjunction with leishmaniasis-expert consensus on the necessity of OH surveillance and key barriers to its realization, compose important transition opportunities. Despite shortfalls in human, animal and vector surveillance, existing system characteristics, structures and practices comprise a promising basis for developing OH cross-sectoral leishmaniasis surveillance activities in Greece.

Bayesian spatio-temporal modeling to assess the effect of land-use changes on the incidence of Cutaneous Leishmaniasis in the Brazilian Amazon

Cutaneous Leishmaniasis (CL) is a vector-borne disease caused by a protozoan of the genus Leishmania and is considered one of the most important neglected tropical diseases. The Brazilian Amazon Forest harbors one of the highest diversity of Leishmania parasites and vectors and is one of the main focuses of the disease in the Americas. Previous studies showed that some types of anthropogenic disturbances have affected the abundance and distribution of CL vectors and hosts; however, few studies have thoroughly investigated the influence of different classes of land cover and land-use changes on the disease transmission risk. Here, we quantify the effect of land use and land-cover changes on the incidence of CL in all municipalities within the Brazilian Amazon Forest, from 2001 to 2017. We used a structured spatiotemporal Bayesian model to assess the effect of forest cover, agriculture, livestock, extractivism, and- deforestation on CL incidence, accounting for confounding variables such as population, climate, socioeconomic, and spatiotemporal random effects. We found that the increased risk of CL was associated with deforestation, especially modulated by a positive interaction between forest cover and livestock. Landscapes with ongoing deforestation for extensive cattle ranching are typically found in municipalities within the Amazon Frontier, where a high relative risk for CL was also identified. These findings provide valuable insights into developing effective public health policies and land-use planning to ensure healthier landscapes for people.

Effect of indoor residual spraying on sandfly abundance and incidence of visceral leishmaniasis in India, 2016-22: an interrupted time-series analysis and modelling study

BACKGROUND

Efforts to eliminate visceral leishmaniasis in India mainly consist of early detection and treatment of cases and indoor residual spraying with insecticides to kill the phlebotomine sandfly Phlebotomus argentipes that transmits the causative Leishmania protozoa. In this modelling study, we aimed to estimate the effect of indoor residual spraying (IRS) on vector abundance and transmission of visceral leishmaniasis in India.

METHODS

In this time-series analysis and modelling study, we assessed the effect of IRS on vector abundance by using indoor vector-abundance data (from 2016 to 2022) and IRS quality-assurance data (from 2017-20) from 50 villages in eight endemic blocks in India where IRS was implemented programmatically. To assess a potential dose-response relation between insecticide concentrations and changes in sandfly abundance, we examined the correlation between site-level insecticide concentrations and the site-level data for monthly sandfly abundances. We used mathematical modelling to link vector data to visceral leishmaniasis case numbers from the national Kala-Azar Management Information System registry (2013-21), and to predict the effect of IRS on numbers of averted cases and deaths.

FINDINGS

IRS was estimated to reduce indoor sandfly abundance by 27% (95% CI 20-34). Concentrations of insecticides on walls were significantly-but weakly-associated with the degree of reduction in vector abundance, with a reduction of -0·0023 (95% CI -0·0040 to -0·0007) sandflies per mg/m2 insecticide (p=0·0057). Reported case numbers of visceral leishmaniasis were well explained by trends in vector abundance. Village-wide IRS in response to a newly detected case of visceral leishmaniasis was predicted to reduce disease incidence by 6-40% depending on the presumed reduction in vector abundance modelled.

INTERPRETATION

Indoor residual spraying has substantially reduced sandfly abundance in India, which has contributed to reductions in visceral leishmaniasis and related deaths. To prevent the re-emergence of visceral leishmaniasis as a public health problem, surveillance of transmission and sandfly abundance is warranted.

FUNDING

Bill & Melinda Gates Foundation.

TRANSLATION

For the Hindi translation of the abstract see Supplementary Materials section.

Evolutionary divergent clusters of transcribed extinct truncated retroposons drive low mRNA expression and developmental regulation in the protozoan Leishmania

BACKGROUND

The Leishmania genome harbors formerly active short interspersed degenerated retroposons (SIDERs) representing the largest family of repetitive elements among trypanosomatids. Their substantial expansion in Leishmania is a strong predictor of important biological functions. In this study, we combined multilevel bioinformatic predictions with high-throughput genomic and transcriptomic analyses to gain novel insights into the diversified roles retroposons of the SIDER2 subfamily play in Leishmania genome evolution and expression.

RESULTS

We show that SIDER2 retroposons form various evolutionary divergent clusters, each harboring homologous SIDER2 sequences usually located nearby in the linear sequence of chromosomes. This intriguing genomic organization underscores the importance of SIDER2 proximity in shaping chromosome dynamics and co-regulation. Accordingly, we show that transcripts belonging to the same SIDER2 cluster can display similar levels of expression. SIDER2 retroposons are mostly transcribed as part of 3'UTRs and account for 13% of the Leishmania transcriptome. Genome-wide expression profiling studies underscore SIDER2 association generally with low mRNA expression. The remarkable link of SIDER2 retroposons with downregulation of gene expression supports their co-option as major regulators of mRNA abundance. SIDER2 sequences also add to the diversification of the Leishmania gene expression repertoire since ~ 35% of SIDER2-containing transcripts can be differentially regulated throughout the parasite development, with a few encoding key virulence factors. In addition, we provide evidence for a functional bias of SIDER2-containing transcripts with protein kinase and transmembrane transporter activities being most represented.

CONCLUSIONS

Altogether, these findings provide important conceptual advances into evolutionary innovations of transcribed extinct retroposons acting as major RNA cis-regulators.

Accuracy evaluation of diagnostic methods for visceral leishmaniasis in adult patients with and without HIV infection: clinical management implications

Visceral leishmaniasis (VL) poses a serious health threat, particularly when untreated, necessitating accurate diagnosis. While the gold-standard method involves identifying amastigotes in bone marrow aspirate (BMA), this procedure is invasive and occasionally contraindicated. Additionally, when VL is associated with HIV infection the serologies accuracies could be affected. This study aims to evaluate and compare diagnostic methods for VL in patients with and without HIV coinfection. We enrolled prospectively 127 consecutive adult VL patients, 48 (37.8%) of whom had HIV coinfection, in Brazil's Midwestern region, where VL is endemic. Parasitological examination served as the reference standard for accuracy analysis, with index tests including immunofluorescent antibody test (IFAT), immunochromatographic test with rK39 protein (rK39-ICT), and blood polymerase chain reaction (PCR). Specificity assessment involved 430 healthy blood donors from the same endemic area. Ninety-two patients had parasitologically confirmed VL. Among HIV-uninfected patients, rK39-ICT exhibited sensitivity comparable to PCR (93.6%; 95% CI: 83.6-100 vs. 97.8%; 95% CI: 93.6-99.2, respectively) and superior to IFAT (71.1%; 95% CI: 57.9-84.3). However, in HIV-infected patients, rK39-ICT sensitivity was notably lower than PCR (40.0%; 95% CI: 22.5-57.5 vs. 97.4%; 95% CI: 92.5-98.9) and similar to IFAT (67.5%; 95% CI: 52.9-82.0). Combining two serological tests in parallel identified 82.1% of parasitologically confirmed VL cases, with a negative likelihood ratio significantly lower than either test alone. No test achieved a specificity of 90%, and there were no significant differences in specificity observed among the index tests. The positivity rate of parasitological examination in the 127 VL patients was higher in HIV-infected compared to HIV-uninfected patients, 91.3% (95% CI: 83.2-99.4) versus 67.6% (95% CI: 56.9-78.3), respectively. These findings underscore the necessity of accounting for HIV infection when choosing VL diagnostic methods. Although rK39-ICT provides reliable results in HIV-uninfected patients, BMA examination remains crucial for accurate diagnosis in individuals with HIV/AIDS. In cases where bone marrow aspiration is contraindicated, employing IFAT and rK39-ICT in parallel could be considered, as the occurrence of both positive results is uncommon in healthy individuals from endemic areas.

Canine leishmaniasis caused by Leishmania Tropica in southeastern Iran: a case series study

Dogs are the primary reservoirs of Leishmania infantum (L. infantum), but Leishmania tropica (L. tropica) infection is also possible in dogs and can transmitted to humans. The southeast of Iran experiences a high prevalence of canine leishmaniasis (CanL), and veterinarians frequently encounter symptomatic cases. Therefore, from December 2017 to November 2022, the present case series was designed to assess the prevalence of CanL in owned dogs with cutaneous manifestations resembling CanL. A total of 500 owned dogs with dermal lesions from two endemic cities, Zabol and Kerman, were enrolled. Impression smears from skin lesions and popliteal lymph nodes were prepared from all cases, whereas blood samples were gathered from amastigote-positive dogs for serological and molecular surveys. Commercial ELISA was done on sera samples, and two-step nested PCR was used on extracted DNA to amplify variable fragments of the Leishmania species' kinetoplast DNA (kDNA). Leishman bodies were microscopically detected in 7.2% (36/500) of dermal smears. Of the 360 owned dogs from Zabol, 2 have been diagnosed with L. tropica, and 10 have been diagnosed with L. infantum. Out of 140 owned dogs from Kerman, 8 were identified with L. tropica infection, and 16 were infected with L. infantum. Molecular results revealed the presence of 750 full dual-band bases related to the L. tropica species in 10/36 (27.7%) cases, which showed a considerable increase in canine cutaneous leishmaniosis compared with previous studies in southeastern Iran. The noticeable prevalence of L. tropica in owned dogs indicated that the dog's role in cutaneous leishmaniosis should be re-evaluated as a possible animal reservoir in endemic areas.

Pyrazolyl amide-chalcones conjugates: Synthesis and antikinetoplastid activity

A series of novel pyrazolyl amide-chalcones conjugates was synthesized in five steps and evaluated against a range of medically important kinetoplastid parasites including Trypanosoma cruzi, Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense and Leishmania infantum. In addition, the series was also tested for in vitro cytotoxicity activity against human lung fibroblasts and primary mouse macrophages. Among all synthetised compounds, 9b was found to be the most active against T. b. brucei with an IC50 value of 0.51 ± 0.06 μM. Against T. b. rhodesiense, 9n was found to be the most potent with an IC50 value of 0.46 ± 0.07 μM. While against L. infantum, 9a was found to be most active with an IC50 value of 7.16 ± 1.88 μM. Based on the results and SAR, further modifications will be carried out to increase potency.

Immunotherapeutic Strategies as Potential Treatment Options for Cutaneous Leishmaniasis

Cutaneous leishmaniasis (CL), caused by protozoan parasites of the Leishmania genus, is prevalent in tropical and subtropical regions, with important morbidity, particularly in low- to middle-income countries. Current systemic treatments, including pentavalent antimonials and miltefosine, are associated with significant toxicity, reduced efficacy, and are frequently ineffective in cases of severe or chronic CL. Immunotherapies leverage the immune system to combat microbial infection and offer a promising adjunct or alternative approach to the current standard of care for CL. However, the heterogeneous clinical presentation of CL, which is dependent on parasite species and host immunity, may require informed clinical intervention with immunotherapies. This review explores the clinical and immunological characteristics of CL, emphasising the current landscape of immunotherapies in in vivo models and clinical studies. Such immune-based interventions aim to modulate immune responses against Leishmania, with additive therapeutic effects enabling the efficacy of lower drug doses and decreasing the associated toxicity. Understanding the mechanisms that underlie immunotherapy for CL provides critical insights into developing safer and more effective treatments for this neglected tropical disease. Identifying suitable therapeutic candidates and establishing their safety and efficacy are essential steps in this process. However, the feasibility and utility of these treatments in resource-limited settings must also be considered, taking into account factors such as cost of production, temperature stability, and overall patient access.

Evaluation of Loopamp Leishmania detection kit for the diagnosis of cutaneous leishmaniasis in Ethiopia

BACKGROUND

Cutaneous leishmaniasis (CL) in Ethiopia and some parts of Kenya is predominantly caused by Leishmania aethiopica. While skin-slit (SS) microscopy is routinely used for CL diagnosis, more sensitive molecular tests are available. The Loopamp™ Leishmania detection kit (Loopamp) is a robust loop-mediated isothermal amplification (LAMP) assay with the potential for implementation in primary healthcare facilities. In this study, we comparatively assessed the diagnostic accuracy of four methods currently used to diagnose CL: Loopamp, kinetoplast DNA (kDNA) PCR, spliced leader RNA (SL-RNA) PCR and SS microscopy.

METHODS

A study on 122 stored tape disc samples of suspected CL patients was conducted in Gondar, northwestern Ethiopia. Routine SS microscopy results were obtained from all patients. Total nucleic acids were extracted from the tapes and subjected to PCR testing targeting kDNA and SL-RNA, and Loopamp. Diagnostic accuracy was calculated with SS microscopy as a reference test. The limit of detection (LoD) of Loopamp and kDNA PCR were determined for cultured L. aethiopica and Leishmania donovani.

RESULTS

Of the 122 patients, 64 (52.5%) were identified as CL cases based on SS microscopy. Although the PCR tests showed a sensitivity of 95.3% (95% confidence interval [CI] 91.6-99.1), Loopamp only had 48.4% (95% CI 39.6-57.3) sensitivity and 87.9% (95% CI 82.1-93.7) specificity. The LoD of Loopamp for L. donovani was 100-fold lower (20 fg/µl) than that for L. aethiopica (2 pg/µl).

CONCLUSIONS

The Loopamp™ Leishmania detection kit is not suitable for the diagnosis of CL in Ethiopia, presumably due to a primer mismatch with the L. aethiopica 18S rRNA target. Further research is needed to develop a simple and sensitive point-of-care test that allows the decentralization of CL diagnosis in Ethiopia.

Prevention and management of infectious and tropical diseases in kidney transplant recipients residing in European outermost and overseas territories

BACKGROUND

The European Union encompasses 30 outermost and overseas countries and territories (OCTs). Despite a recent increasing activity of renal transplantation in these territories, many patients still undergo transplantation in continental Europe, with follow-up care coordinated between health professionals from both their transplant center and their home region. Each territory has its unique infectious epidemiology which must be known to ensure appropriate care for kidney transplant recipients (KTRs).

AIMS

This paper proposes a pragmatic approach to optimize pre-transplant check-up and to provide an overview of the specific epidemiological features of each region. It offers practical algorithms to help practitioners in managing infected KTR living in these territories. This work advocates for increased collaborative research among European OCTs.

A single Leishmania adenylate forming enzyme of the ANL superfamily generates both acetyl- and acetoacetyl-CoA

Leishmania, a protozoan parasite, is responsible for significant morbidity and mortality worldwide, manifesting as cutaneous, mucocutaneous, and visceral leishmaniasis. These diseases pose a substantial burden, especially in impoverished regions with limited access to effective medical treatments. Current therapies are toxic, have low efficacy, and face growing resistance. Understanding the metabolic pathways of Leishmania, particularly those differing from its host, can unveil potential therapeutic targets. In this study, we investigated the acetyl-CoA synthetase (ACS) enzyme from Leishmania infantum (LiAcs1), which, unlike many organisms, also exhibits acetoacetyl-CoA synthetase (KBC) activity. This dual functionality is unique among ANL superfamily enzymes and crucial for the parasite's reliance on leucine catabolism, energy production and sterol biosynthesis. Our biochemical characterization of LiAcs1 revealed its ability to utilize both acetate and acetoacetate substrates. Additionally, LiAcs1 displayed a distinct CoA substrate inhibition pattern, partially alleviated by acetoacetate. Structural analysis provided insights into the substrate binding flexibility of LiAcs1, highlighting a more promiscuous substrate pocket compared to other ACS or KBC-specific enzymes. Substrate mimetics elucidated its ability to accommodate both small and large AMP-ester derivatives, contributing to its dual ACS/KBC functionality. These findings not only advance our understanding of Leishmania metabolism but also present LiAcs1 as a promising drug target. The dual functionality of LiAcs1 underscores the potential for developing selective inhibitors that could disrupt critical metabolic pathways across Leishmania spp. as it appears this enzyme is highly conserved across this genus. This paves the way for developing novel effective treatments against this devastating disease.

Immunological clues to sex differences in parasitic diseases

The effect of sex on the prevalence and severity of parasitic diseases is an emerging area of research. Several factors underlie sex-based differences, including sociocultural influences that affect exposure to parasites, and physiological disparities linked to biological sex. Hence, human studies must be interpreted cautiously; however, studies conducted under controlled laboratory conditions are important to validate findings in humans. Such research can more effectively elucidate the role of sex-determining physiological factors (particularly their impact on immune responses), as well as the role of sex-specific differences in resistance to, or severity of, parasitic diseases. This review focuses on the overarching impact of biological sex variables on immunity. Both human and rodent experimental data are discussed, with a focus on selected protozoan and helminth infections.

Dogs may carry Leishmania tropica and Leishmania major in their blood circulation: a molecular and hematological study

BACKGROUND

Dogs may be infected with species of Leishmania parasites that are disseminated through blood circulation and invade the internal organs. In this study, we aim to detect the parasite in the blood of dogs using the PCR technique. The present work was performed from February 2022 to May 2023 in Fars Province, southern Iran, where the disease is endemic.

RESULTS

In total, 7(5.1%) out of 135 blood samples, six were identified as Leishmania tropica and one as Leishmania major. We found no trace of Leishmania infantum, which is always known for visceral infection. In addition, no sign of cutaneous lesions or a significant disease was seen in the animals infected with both species. Of 48 dogs with anemia, two were Leishmania positive. The mean value of hematological parameters in the infected dogs was within the normal range except for a significant reduction in the platelet measures (p < 0.05).

CONCLUSIONS

Our data revealed that both Leishmania species, tropica and major, may manifest as viscerotropic leishmaniasis. More investigations are needed to understand the conditions under which these species choose the type of infection. Moreover, our data emphasize the role of asymptomatic dogs in carrying these parasites, a crucial factor in spreading the disease.

The economic burden of visceral leishmaniasis and barriers to accessing healthcare in Tigray, North Ethiopia: A field based study

BACKGROUND

Visceral leishmaniasis (VL) is an important public health problem, which mainly affects the poor rural dwelling communities in Low- and Middle-Income Countries. However, little is known about the health and economic burdens of this disease in East Africa, including Ethiopia. The aim of this study was to assess the household level economic burden of VL among affected communities in Tigray, Northern Ethiopia.

METHODS

Between April and August 2020, a cross-sectional household survey was conducted on 96 patients who had been treated for VL within 12 months prior to the survey, in six districts of Tigray. Data on households' health seeking behavior, direct and indirect costs and coping strategies were collected using a structured questionnaire and the responses were analyzed using SPSS software.

RESULTS

Most (82%) of the patients surveyed were males and the majority (74%) of them were between 16 and 30 years of age. The education level of participants was very low: over 33% had not received any form of education; 48% of patients were farmers dependent on subsistence agriculture and about 32% were daily laborers. Just under half of household families (46%) resided in "poor houses" with structures made from entirely local materials. Forty-one percent of patients from the surveyed households had traveled 48 to 72 kilometers to reach VL treatment hospitals. The median total household cost for one VL episode was estimated to be US$ 214. This is equated to 18% of the mean total annual household income or 72.5% of annual per capita income of the study population. More than 80% of the households surveyed incurred catastrophic costs of VL, where this is defined as exceeding 10% of annual household income. The median delay between the onset of symptoms and arrival at a care provider hospital was 37 days; once the patient arrived at hospital, the median delay during diagnosis was 3 days. Direct and indirect costs represented 44% and 56% of the total costs incurred, respectively. To cope with VL treatment costs, 43% of the households used more than one coping strategy: 48% took out loans, 43% sold livestock and 31% of households mobilized cash savings.

CONCLUSIONS

VL in Tigray is concentrated among young males with low educational background and mostly engaged in subsistence economic activities. Despite the free diagnostic and treatment provisions that were available at public hospitals at the time of the study, our work shows that the household economic burden of the disease had significant impact among VL-affected communities in Tigray. Initiating community awareness towards prevention, early treatment seeking and decentralization of VL treatment centers are strongly recommended. In addition, we recommend efforts to reduce household treatment costs through transport and food provisions for patients (and their accompanying carers where possible) or through cash reimbursement for patients who complete treatment at public hospitals, in order to reduce the barriers to seeking treatment for this life-threatening disease.

Serum Levels of Vitamins and Trace Elements in Patients with Visceral Leishmaniasis: a Systematic Review and Meta-analysis

Visceral leishmaniasis (VL), a fatal disease prevalent in more than 70 countries, poses significant health challenges, particularly in poor communities with limited access to healthcare. Vitamins and trace elements play a crucial role in immune function and may influence susceptibility to VL. This systematic review and meta-analysis aimed to assess the differences in serum vitamin and trace element levels in VL patients compared to healthy individuals. We conducted an extensive search of databases (PubMed, Embase, and Google Scholar) to identify potentially eligible articles published from inception to June 2023. Data extraction and quality assessment were carried out by two reviewers independently. RevMan software (version 5.4) was used for analysis. Standardized mean difference (SMD) with a confidence interval (CI) of 95% was used to summarize the findings. Ten studies comprising 546 VL patients and 535 controls were included in our study. The findings revealed significantly reduced serum retinol levels in VL patients in comparison to controls (SMD: - 0.67; 95% CI: [- 1.05, - 0.28]; p = 0.0008). Serum zinc levels were also substantially lower in VL patients, regardless of controls recruited from endemic (SMD: - 2.65; 95% CI: [- 3.86, - 1.44]; p < 0.0001) or non-endemic regions (SMD: - 1.99; 95% CI: [- 3.02, - 0.96]; p < 0.0002). However, VL patients exhibited significantly increased serum copper levels compared to controls (SMD: 2.51; 95% CI: [0.70, 4.32]; p = 0.007). Patients with VL had lower serum levels of zinc and retinol and higher levels of copper, indicating a possible role of these micronutrients in influencing VL susceptibility and progression.

Incidence and persistence of asymptomatic Leishmania infection among HIV-infected patients in Trang province, Southern Thailand: A cohort study

Leishmaniasis poses a significant health burden, particularly among immunocompromised patients. In Thailand, Leishmania infection caused by Leishmania martiniquensis and Leishmania orientalis lacks information about the incidence and risk factors among HIV-infected populations. This longitudinal cohort study aimed to investigate the incidence and persistence of Leishmania infection among HIV-infected individuals in an affected area, Trang Province, Southern Thailand. The study also identified risk factors associated with the incidence of Leishmania infection. The study enrolled 373 participants in the HIV clinic, Trang Hospital, who initially tested negative for Leishmania infection during 2015-2016, and 133 individuals initially tested positive for Leishmania infection. Thus, follow-up visits of 506 participants occurred during 2018-2019. Direct Agglutination Test (DAT) and nested PCR (nPCR) identified incidents and persistent cases of Leishmania infection. Cox proportional-hazards regression analyses were performed to assess risk factors for the incidence of Leishmania infection. Among the initially negative group, 12 incident cases comprised one L. orientalis infection and 11 seropositive cases using DAT, resulting in a cumulative incidence of 3.2% and an incidence density of 10.38 per 1000 person-years. Increasing age was a significant predictor of the incidence of Leishmania infection. Five persistent cases comprised one Leishmania donovani complex and four seropositive cases using DAT in the initially positive group, with a cumulative persistence rate of 3.7% and a persistence density of 12.85 per 1000 person-years. All patients were asymptomatic. This study sheds light on the incidence and persistence of Leishmania infection among HIV-infected individuals in Trang Province, Southern Thailand, underscoring the importance of continued monitoring and tailored interventions to mitigate the impact of this co-infection.

Thiadiazine-thiones as inhibitors of leishmania pteridine reductase (PTR1) target: investigations and in silico approach

Leishmaniasis is a widespread parasitic disease and is one of the major public health concerns in developing countries. Many drugs have been identified for leishmania as targets, but the potential toxicity and long-term treatment remain the most significant problems in terms of further development. The present study employed physicochemical investigations, structure-based virtual screening, ADMET analysis, molecular dynamics simulation, and MM-PBSA, to identify potential compounds for Leishmania. We evaluated 30,926 natural products from the NPASS database, and four potentials passed the pharmacokinetic ADMET studies and were verified using the molecular docking approach. Molecular docking results showed good binding interaction of the compounds with the active site of leishmania pteridine reductase enzyme PTR1, with compound TTC1 showing FRED and Autodock binding energies of -10.33 and -10.94, respectively, which were comparable with the antileishmania drugs of Allopurinol, Miltefosine and the original ligand, methotrexate. TTC1 compound was found to be favorable for hydrophobic interaction with PTR1. In addition, the physicochemical properties of the compounds were studied using the SwissADME web server. All compounds followed Lipinski's rule of five and can be considered as good oral candidates. The analysis of the 100 ns molecular dynamics simulation results based on the best-docked TTC1 with PTR1 receptor demonstrates stable interactions, and the complex undergoes low conformational fluctuations. The average of the calculated binding free energy of the TTC1-1e7w complex is (-68.67 kJ/mol), and the result demonstrated that the TTC1 promoted stability to the Leishmania-PTR1 complex. The potential compounds can be further explored for their antileishmanial activity.Communicated by Ramaswamy H. Sarma.

Leishmania major-induced alteration of host cellular and systemic copper homeostasis drives the fate of infection

Copper plays a key role in host-pathogen interaction. We find that during Leishmania major infection, the parasite-harboring macrophage regulates its copper homeostasis pathway in a way to facilitate copper-mediated neutralization of the pathogen. Copper-ATPase ATP7A transports copper to amastigote-harboring phagolysosomes to induce stress on parasites. Leishmania in order to evade the copper stress, utilizes a variety of manipulative measures to lower the host-induced copper stress. It induces deglycosylation and degradation of host-ATP7A and downregulation of copper importer, CTR1 by cysteine oxidation. Additionally, Leishmania induces CTR1 endocytosis that arrests copper uptake. In mouse model of infection, we report an increase in systemic bioavailable copper in infected animals. Heart acts as the major organ for diverting its copper reserves to systemic circulation to fight-off infection by downregulating its CTR1. Our study explores reciprocal mechanism of manipulation of host copper homeostasis pathway by macrophage and Leishmania to gain respective advantages in host-pathogen interaction.

Determination of key hub genes in Leishmaniasis as potential factors in diagnosis and treatment based on a bioinformatics study

Leishmaniasis is an infectious disease caused by protozoan parasites from different species of leishmania. The disease is transmitted by female sandflies that carry these parasites. In this study, datasets on leishmaniasis published in the GEO database were analyzed and summarized. The analysis in all three datasets (GSE43880, GSE55664, and GSE63931) used in this study has been performed on the skin wounds of patients infected with a clinical form of leishmania (Leishmania braziliensis), and biopsies have been taken from them. To identify differentially expressed genes (DEGs) between leishmaniasis patients and controls, the robust rank aggregation (RRA) procedure was applied. We performed gene functional annotation and protein-protein interaction (PPI) network analysis to demonstrate the putative functionalities of the DEGs. The study utilized Molecular Complex Detection (MCODE), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) to detect molecular complexes within the protein-protein interaction (PPI) network and conduct analyses on the identified functional modules. The CytoHubba plugin's results were paired with RRA analysis to determine the hub genes. Finally, the interaction between miRNAs and hub genes was predicted. Based on the RRA integrated analysis, 407 DEGs were identified (263 up-regulated genes and 144 down-regulated genes). The top three modules were listed after creating the PPI network via the MCODE plug. Seven hub genes were found using the CytoHubba app and RRA: CXCL10, GBP1, GNLY, GZMA, GZMB, NKG7, and UBD. According to our enrichment analysis, these functional modules were primarily associated with immune pathways, cytokine activity/signaling pathways, and inflammation pathways. However, a UBD hub gene is interestingly involved in the ubiquitination pathways of pathogenesis. The mirNet database predicted the hub gene's interaction with miRNAs, and results revealed that several miRNAs, including mir-146a-5p, crucial in fighting pathogenesis. The key hub genes discovered in this work may be considered as potential biomarkers in diagnosis, development of agonists/antagonist, novel vaccine design, and will greatly contribute to clinical studies in the future.

Monitoring of Leishmania infantum in captive non-human primates in Spain

Cases of Leishmania infantum infection have recently been reported in non-human primates (NHPs) in Spain causing severe clinical disease in critically endangered orangutans (Pongo pygmaeus pygmaeus). The aim of this study was to determine exposure and risk factors associated with L. infantum infection in NHPs housed in zoos and wildlife rescue centers (WRC) in Spain. Between 2007 and 2023, sera from 252 NHPs belonging to 47 different species were collected at 15 centers. Indirect immunofluorescence was used to detect the presence of antibodies against L. infantum (cut-off ≥1:80). In addition, hair samples from 78 individuals were tested for Leishmania kDNA by real-time quantitative PCR (qPCR). Anti-Leishmania antibodies were detected in 4.0 % (10/252; 95 %CI: 1.6-6.4) of the NHPs tested at 26.7 % (4/15) of the centers sampled. Twenty-two NHPs were longitudinally sampled between 2010 and 2023: one ring-tailed lemur (Lemur catta) seroconverted and a seropositive orangutan increased antibody titers during the study period. Leishmania infantum kDNA was found in 62.8 % (49/78; 95 %CI: 52.1-73.6) of animals and at all centers sampled (100 %; 7/7). Phylogenetic analysis revealed high homology between the sequence obtained and strains previously isolated in humans, dogs and captive and free-living wildlife species in Spain. To the authors´ knowledge, this is the first report of Leishmania kDNA detection in NHP hair samples. The results indicate that hair samples could be a useful, non-invasive method of detection of L. infantum infection in these species. This is also the first large-scale survey of L. infantum conducted in NHP species in Europe. We report for the first time the presence of Leishmania kDNA in nine different NHP species belonging to the families Cercopithecidae, Lemuridae, and Hylobatidae, expanding the host range for this parasite. The main risk factors associated with L. infantum infection were: age (≥5 years old) and body size (large). Our results demonstrate widespread circulation of this parasite among NHPs housed in Spain, which could be of conservation and public health concern. Monitoring and control programs should be implemented in zoos and WRCs to minimize the risk of NHP exposure to L. infantum in endemic areas worldwide.

Advances in Leishmania Vaccines: Current Development and Future Prospects

Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania. As approved human vaccines are not available, treatment and prevention rely heavily on toxic chemotherapeutic agents, which face increasing resistance problems. The development of effective vaccines against human leishmaniasis is of utmost importance for the control of the disease. Strategies that have been considered for this purpose range from whole-killed and attenuated parasites to recombinant proteins and DNA vaccines. The ideal vaccine must be safe and effective, ensuring lasting immunity through a robust IL-12-driven Th1 adaptive immune response. Despite some success and years of effort, human vaccine trials have encountered difficulties in conferring durable protection against Leishmania, a problem that may be attributed to the parasite's antigenic diversity and the intricate nature of the host's immune response. The aim of this review is to provide a thorough overview of recent advances in Leishmania vaccine development, ranging from initial trials to recent achievements, such as the ChAd63-KH DNA vaccine, which underscores the potential for effective control of leishmaniasis through continued research in this field.

Kupffer Cells and Hepatocytes: A Key Relation in the Context of Canine Leishmaniasis

Human zoonotic visceral leishmaniasis (ZVL) and canine leishmaniasis (CanL) constitute a major public and veterinary health concern and are both caused by the infection with the protozoan parasite Leishmania infantum. One of the main target organs in CanL is the liver. This complex organ, composed of various highly specialized cell types, has garnered significant attention from the scientific community as a crucial player in innate immune functions. In the context of CanL, liver infection by parasites and the host immune response generated strongly influence the disease outcome. Thus, taking advantage of a co-culture system involving canine hepatocytes and L. infantum-infected autologous Kupffer cells (KCs), allowing cell-to-cell interaction, the current report aims to shed light on the hepatocyte-KCs immune interaction. The co-culture of infected KCs with hepatocytes revealed a vital role of these cells in the activation of a local immune response against L. infantum parasites. Although KCs alone can be immunologically silenced by L. infantum infection, the cell-to-cell interaction with hepatocytes in co-culture can lead to local immune activation. In co-culture it was observed gene expression increased the number of innate immune receptors, specifically cell membrane TLR2 and cytoplasmatic NOD1 along with high TNF-α generation. Altogether, these results suggest that the immune response generated in co-culture could induce the recruitment of other circulating cells to contain and contribute to the resolution of the infection in the liver. This work also enhances our understanding of the liver as a vital organ in innate immunity within the context of CanL.

Shared challenges to the control of complex intracellular neglected pathogens

The complex intracellular pathogens Mycobacterium tuberculosis, Mycobacterium leprae, Leishmania spp., and Burkholderia pseudomallei, which cause tuberculosis, leprosy, leishmaniasis, and melioidosis respectively, represent major health threats with a significant global burden concentrated in low- and middle-income countries. While these diseases vary in their aetiology, pathology and epidemiology, they share key similarities in the biological and sociodemographic factors influencing their incidence and impact worldwide. In particular, their occurrence in resource-limited settings has important implications for research and development, disease prevalence and associated risk factors, as well as access to diagnostics and therapeutics. In accordance with the vision of the VALIDATE (VAccine deveLopment for complex Intracellular neglecteD pAThogeEns) Network, we consider shared challenges to the effective prevention, diagnosis and treatment of these diseases as shaped by both biological and social factors, illustrating the importance of taking an interdisciplinary approach. We further highlight how a cross-pathogen perspective may provide valuable insights for understanding and addressing challenges to the control of all four pathogens.

Untargeted Liquid Chromatography-High-Resolution Mass Spectrometry Metabolomic Investigation Reveals Altered Lipid Content in Leishmania infantum Lacking Lipid Droplet Protein Kinase

Leishmaniasis is a complex disease caused by different species of Leishmania. To date, no vaccine for humans or ideal therapy has been developed owing to the limited efficacy and toxicity of available drugs, as well as the emergence of resistant strains. Therefore, it is necessary to identify novel therapeutic targets and discover therapeutic options for leishmaniasis. In this study, we evaluated the impact of deleting the lipid droplet protein kinase (LDK) enzyme in Leishmania infantum using an untargeted metabolomics approach performed using liquid chromatography and high-resolution mass spectrometry. LDK is involved in lipid droplet biogenesis in trypanosomatids. Thirty-nine lipid metabolites altered in the stationary and logarithmic growth phases were noted and classified into five classes: (1) sterols, (2) fatty and conjugated acids, (3) ceramides, (4) glycerophosphocholine and its derivatives, and (5) glycerophosphoethanolamine and its derivatives. Our data demonstrated that glycerophosphocholine and its derivatives were the most affected after LDK deletion, suggesting that the absence of this enzyme promotes the remodeling of lipid composition in L. infantum, thus contributing to a better understanding of the function of LDK in this parasite.

Biogenesis of EVs in Trypanosomatids

Trypanosomes are protozoan parasites responsible for human diseases such as Chagas disease, African trypanosomiasis, and leishmaniasis. These organisms' growth in various environments and exhibit multiple morphological stages, while adapting their surface components. They acquire and release materials extensively to get nutrients and manage interactions with the extracellular environment. They acquire and utilize proteins, lipids, and carbohydrates for growth via using membrane transport and endocytosis. Endocytosis takes place through distinct membrane areas known as the flagellar pocket and cytostome, depending on the parasite species and its developmental stage. Some forms establish a complex endocytic system to either store or break down the absorbed materials. In contrast, membrane transport facilitates the uptake of small molecules like amino acids, carbohydrates, and iron via particular receptors on the plasma membrane. Concurrently, these parasites secrete various molecules such as proteins, enzymes, nucleic acids, and glycoconjugates either in soluble form or enclosed in extracellular vesicles, which significantly contribute to their parasitic behavior. These activities require exocytosis through a secretory pathway in certain membrane domains such as the flagellum, flagellar pocket, and plasma membrane, which are controlled at various developmental stages. The main features of the endocytic and exocytic mechanisms, as well as the organelles involved, are discussed in this chapter along with their connection to the formation of exosomes and extracellular vesicles in the Tritryp species.

Stigma associated with cutaneous leishmaniasis in rural Sri Lanka: development of a conceptual framework

BACKGROUND

There is limited knowledge about the stigma associated with cutaneous leishmaniasis (CL) in Sri Lanka. To ensure that leishmaniasis researchers focus on CL-associated stigma, we provide an evidence-based framework that can be used in future research.

METHODS

We conducted a systematic review on CL-associated stigma using international evidence and carried out a multimethod qualitative study in the Anuradhapura district in Sri Lanka. Based on that, we identified manifestations of stigma, drivers and facilitators that we synthesised to develop a conceptual framework on CL-associated stigma.

RESULTS

Our framework consists of drivers, facilitators and self-stigma experienced by people with CL. Stigma drivers included fear, misbeliefs and misconceptions about CL; the belief that wounds are disfiguring; the treatment burden and implied blame. Facilitators that reduced stigma included knowledge of the curability of CL and awareness that CL is not contagious. The nature of social interactions in rural communities enhanced stigma formation. We identified various enacted, felt and internalised stigma experiences of people with CL.

CONCLUSIONS

We developed a conceptual framework of the stigma associated with CL that can be used to develop targeted interventions to increase CL awareness, address stigma and improve the quality of life for CL patients.

Leishmania Infection among HIV-Infected Patients in a Southern Province of Thailand: A Cross-Sectional Study

Leishmaniasis, a neglected tropical disease, imposes a notable health burden, especially on immunocompromised individuals such as HIV patients. Recognizing its prevalence and risk factors in specific populations is vital for effective prevention. This study in Satun Province, southern Thailand, aimed to ascertain leishmaniasis prevalence and identify associated risks among HIV-infected patients. A cross-sectional study was conducted among 650 HIV-infected individuals at a tertiary care hospital. Data on demographic characteristics, clinical parameters, and potential risk factors were collected. Individual plasma, buffy coat, and saliva samples were collected. Leishmania infection was determined using the direct agglutination test and nested polymerase chain reaction (nPCR) of nPCR-buffy coat and nPCR-saliva. The association between risk factors and Leishmania infection was assessed with logistic regression analysis. The prevalence of Leishmania infection was 8.61% (56/650). Species was identified among 20 HIV-infected patients as follows: Leishmania orientalis (n = 14), Leishmania martiniquensis (n = 4), and Leishmania donovani complex (n = 2). The factors associated with Leishmania infection included age (adjusted odds ratio [OR] = 1.03), intravenous drug use (adjusted OR = 2.39), CD4 cell count <500 cells/mm3 (adjusted OR = 2.40), and a viral load ≥50 copies/mL (adjusted OR = 5.16). The prevalence of Leishmania infection among HIV-infected patients in Satun Province was considerable. These findings underscore the need for integrated care and targeted interventions to address this infection and improve public health outcomes. Further research and collaborative efforts are warranted to develop effective prevention and control strategies for Leishmania infection in the HIV-infected Thai population.

Spotlight on Leishmaniasis Research: Insights from the Special Issue "Emerging Topics in Leishmaniasis Research"

Leishmaniases, caused by dixenous trypanosomatids from the Leishmaniinae subfamily (over 20 Leishmania species), manifest in three primary clinical forms: visceral (VL), cutaneous (CL), and mucocutaneous (MCL) [...].

The role of economic factors in shaping and constituting the household burden of neglected tropical diseases of the skin: Qualitative findings from Ghana and Ethiopia

Tracers of health system equity, neglected tropical diseases (NTDs) disproportionately affect marginalized populations. NTDs that manifest on the skin - "skin NTDs" - are associated with scarring, disfigurement, physical disability, social exclusion, psychological distress, and economic hardship. To support development and evaluation of appropriate intervention strategies, we aimed to improve understanding of the role of economic factors in shaping and constituting the burden that skin NTDs place on households. We collected data in 2021 in two predominantly rural districts: Atwima Mponua in Ghana (where Buruli ulcer, yaws, and leprosy are endemic) and Kalu in Ethiopia (where cutaneous leishmaniasis and leprosy are endemic). We conducted interviews (n = 50) and focus group discussions (n = 14) that explored economic themes with affected individuals, caregivers, and community members and analysed the data thematically using a pre-defined framework. We found remarkable commonalities across countries and diseases. We developed a conceptual framework which illustrates skin NTDs' negative economic impact, including financial costs of care-seeking and reductions in work and schooling; categorises coping strategies by their degree of risk-pooling; and clarifies the mechanisms through which skin NTDs disproportionately affect the poorest. Despite health insurance schemes in both countries, wide-ranging, often harmful coping strategies were reported. Traditional healers were often described as more accessible, affordable and offering more flexible payment terms than formal health services, except for Ethiopia's well-established leprosy programme. Our findings are important in informing strategies to mitigate the skin NTD burden and identifying key drivers of household costs to measure in future evaluations. To reduce skin NTDs' impact on households' physical, mental, and economic wellbeing, intervention strategies should address economic constraints to prompt and effective care-seeking. While financial support and incentives for referrals and promotion of insurance enrolment may mitigate some constraints, structural interventions that decentralise care may offer more equitable and sustainable access to skin NTD care.

Canine leishmaniosis global prevalence over the last three decades: a meta-analysis and systematic review

Leishmaniosis by Leishmania infantum is a zoonotic vector-borne disease transmitted to humans and dogs by the bite of female sand-flies. The domestic dog is the main reservoir and infected dogs may show or not clinical symptoms. The prevalence of infection in dogs varies according to the population studied, the geographic area, and the diagnostics employed. This study aims to estimate the global prevalence, subgrouping per continent, country, diagnostic test and selected risk factors. Cross-sectional studies (n=150; from 1990 to 2020) estimating the prevalence of the infection by Leishmania infantum were extracted from four electronic databases. The pooled global prevalence obtained by random-effects meta-analysis was 15.2 % (95 %CI 13.6-16.9), mostly in rural (19.5 %) and owned dogs (16.5 %). Prevalence varied if the diagnosis was made by western blot (WB, 32.9 %), cellular immunity tests (27.5 %), ELISA (17 %), PCR (16.9 %), IFAT (15.9 %), rapid tests and direct agglutination test (DAT, 11.5 %), cytology/immunohistochemistry (13.1 %), culture (8.6 %). A small studies bias (P<0.005) in the overall prevalence meta-analysis, due to the impact of small-size studies on the overall results was found. Moreover, a continent-related bias was found regarding rapid test, DAT (P=0.021), and WB (P<0.001), as these assays are mainly used in South American studies. A study period bias (P=0.033) and a publication year bias (P=0.002) were detected for PCR, as the test was not employed before the year 2000. In conclusion, a high prevalence of canine leishmaniosis worldwide and high heterogeneity among studies were found.

Epidemiological Mapping of Cutaneous Leishmaniasis in Saudi Arabia: An Observational Descriptive Study

Cutaneous leishmaniasis (CL) is a parasitic disease that affects individuals worldwide. An epidemiological observational population-cohort study was conducted on the basis of comprehensive research on CL incidence in Saudi and non-Saudi residents. The Ministry of Health recorded the incidence of CL between January 2020 and December 2022. The chi-square test was used to analyze the data and determine CL incidence rates in age-specific incidence rates (ASIRs) and gender between Saudi and non-Saudi residents in Saudi Arabia. The study found that between 2020 and 2022, there were 2280 cases of CL in Saudi Arabia, with 1367 and 913 cases in men and women, respectively. Of Saudi nationals, 64.26% and 12.91% were male and female, respectively. The frequency of CL was higher (87.09%) among non-Saudi residents than among Saudi nationals, with a statistically significant difference (P = 0.001) between the two groups. The ASIRs for CL were higher in patients aged 15-45 years. This study revealed variations in CL incidence rates among the 13 administrative regions; Qassim, followed by Aseer, Ha'il, and Madinah, had higher rates than the other regions. These findings indicate the need for targeted interventions and public health strategies to reduce the burden on CL, particularly among non-Saudi residents.

Abundance and Leishmania infection patterns of the sand fly Psathyromyia cratifer in Southern Mexico

BACKGROUND

Localized cutaneous leishmaniasis (LCL) is a serious public health problem in Southern Mexico. Six species of Phlebotominae (Diptera: Psychodidae) have been found to be infected with Leishmania (Leishmania) mexicana, the causative agent of LCL in the region. However, little is known about the biology and potential participation of Psathyromyia cratifer in the Leishmania transmission cycle in Mexico, and the Americas. The present study provides evidence of temporal infection caused by Leishmania in Psathyromyia cratifer as well as data on its population dynamics in a LCL endemic area during the well-known transmission cycle of Leishmania in Southern Mexico.

METHODOLOGY/PRINCIPAL FINDINGS

Individual specimens of Psathyromyia cratifer were collected in four sites over the course of five months (from November 2020 through March 2021) using animal-baited, human-baited, and light traps. The temporal activity pattern (month + hour) of Psathyromyia cratifer was assessed along with its relationship with environmental variables. Moreover, Leishmania DNA and blood meals were analyzed and detected in female sand flies. This evidenced an infection rate ranging from 8% to 83%, and the record of Homo sapiens and Ototylomys phyllotis as blood hosts of this sand fly species. High abundances of these sand flies in human-baited traps were recorded which revealed the marked anthropophilic behavior of Psathyromyia cratifer. As regards the transmission dynamics of the parasite within the region, it was observed that the potential highest epidemiological risk for Leishmania transmission by Psathyromyia cratifer occurred during the months of January and March.

CONCLUSION

This is the first contribution ever made to both the population dynamic and the temporal Leishmania prevalence patterns in Psathyromyia cratifer. The resulting findings suggest that this sand fly specimen is the sixth potential vector of L. (L.) mexicana in Southern Mexico. Nonetheless, various biology, behavior, and ecology strands are yet to be addressed. The latter, to determine the role it plays in the transmission dynamics of the parasite within the region, and other areas of the country.

Ecological study measuring the association between conflict, environmental factors, and annual global cutaneous and mucocutaneous leishmaniasis incidence (2005-2022)

BACKGROUND

Cutaneous and mucocutaneous leishmaniasis (CL/ML) cause significant morbidity globally and are vulnerable to changes from environmental events and conflict. In this ecological study, we aim to measure the associations between annual CL/ML cases, conflict intensity, and environmental factors between 2005 and 2022 globally.

METHODS

We pulled annual case data from the WHO for 52 nations that had conflict intensity scores (ranging from 1-10) from the Bertelsmann Transformation Index. Using Earth observation tools, we gathered temperature, precipitation, vegetation, and humidity data, in addition to data on annual estimates of population, internal displacement, and GDP. We fit a negative binomial generalized additive model with a random nation-level intercept.

RESULTS

Conflict was positively associated with increased CL/ML across the studied nations (IRR: 1.09, 95% CI: 1.01-1.16, p = 0.02). Given this, intense conflict (a score of ten) was associated with over double the risk of CL/ML compared to the lowest conflict levels (score of one). We also identified a curvilinear relationship between mean temperature and cases, as well as between vegetation level and cases. Each had small pockets of significant increased and decreased risk, respectively. Larger mean humidity ranges were negatively associated with cases. Importantly, the relationship between conflict intensity and cases was mediated by displacement.

DISCUSSION

Conflict is significantly associated with increased CL/ML cases. This is especially true at higher conflict levels, marking when conflict turns violent. The destruction of critical infrastructure (e.g., that related to healthcare, water, and sanitation) often seen during conflict could drive this association. Such environments can be hospitable to sandflies and can heighten individuals' vulnerability through increased malnutrition, poverty, and displacement. Understanding this relationship is crucial for public health preparedness and response, especially as conflicts become increasingly violent and protracted.

Thiadiazine thione derivatives as anti-leishmanial agents: synthesis, biological evaluation, structure activity relationship, ADMET, molecular docking and molecular dynamics simulation studies

During last decades, 3,5-disubstituted-tetrahydro-2H-thiadiazine-2-thione scaffold remains the center of interest due to their ease of preparation, diverse range substituents at N-3 and N-5 positions, and profound biological activities. In the current study, a series of 3,5-disubstituted-tetrahydro-2H-thiadiazine-2-thiones were synthesized in good to excellent yield, and the structure of the compounds were confirmed by various spectroscopic techniques such as FTIR, 1H-NMR, 13C-NMR and Mass spectrometry, and finally evaluated against Leishmania major. Whereas, all the evaluated compounds (1-33), demonstrate potential leishmanicidal activities with IC50 values in the range of (1.30- 149.98 uM). Among the evaluated compounds such as 3, 4, 6, and 10 exhibited excellent leishmanicidal activities with IC50 values of (2.17 μM), (2.39 μM), (2.00 μM), and (1.39 μM), respectively even better than the standard amphotericin B (IC50 = 0.50) and pentamidine (IC50 = 7.52). In order to investigate binding interaction of the most active compounds, molecular docking study was conducted with Leishmania major. Further molecular dynamic simulation study was also carried out to assess the stability and correct binding of the most active compound 10, within active site of the Leishamania major. Likewise, the physiochemical properties, drug likeness, and ADMET of the most active compounds were investigated, it was found that none of the compounds violate Lipiniski's rule of five, which show that this class of compounds had enough potential to be used as drug candidate in near future.Communicated by Ramaswamy H. Sarma.

Extracellular vesicles release from protozoa parasite and animal model

Diseases caused by protozoan parasites, such as leishmaniasis, trypanosomiasis, and malaria, are highly complex and together continue to cause high annual morbidity and mortality. The search for new compounds in environmental biodiversity, repositioning known drugs, and developing vaccines using old and innovative technologies have been employed to discover vaccines and new and alternative treatments. Extracellular vesicles (EVs) can carry parasite antigens, creating a new possibility to develop an effective and affordable platform for treatment, vaccines, and drug delivery. Thus, the evaluation of EVs in animal models can and should be explored among the countless biomedical applications. Herein, we will address the concept of EVs, their acquisition and characterization in protozoan parasite models, and the primary studies using these vesicles in therapeutic applications.

Transcriptome and proteome changes triggered by overexpression of the transcriptional regulator Maf1 in the human pathogen Leishmania major

Maf1, originally described as a repressor of RNA polymerase III (RNAP III) transcription in yeast, participates in multiple functions across eukaryotes. However, the knowledge about Maf1 in protozoan parasites is scarce. To initiate the study of Maf1 in Leishmania major, we generated a cell line that overexpresses this protein. Overexpression of Maf1 led to a significant reduction in the abundance of tRNAs, 5S rRNA, and U4 snRNA, demonstrating that Maf1 regulates RNAP III activity in L. major. To further explore the roles played by Maf1 in this microorganism, global transcriptomic and proteomic changes due to Maf1 overexpression were determined using RNA-sequencing and label-free quantitative mass spectrometry. Compared to wild-type cells, differential expression was observed for 1082 transcripts (615 down-regulated and 467 up-regulated) and 205 proteins (132 down-regulated and 73 up-regulated) in the overexpressing cells. A correlation of 44% was found between transcriptomic and proteomic results. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the differentially expressed genes and proteins are mainly involved in transcription, cell cycle regulation, lipid metabolism and transport, ribosomal biogenesis, carbohydrate metabolism, autophagy, and cytoskeleton modification. Thus, our results suggest the involvement of Maf1 in the regulation of all these processes in L. major, as reported in other species, indicating that the functions performed by Maf1 were established early in eukaryotic evolution. Notably, our data also suggest the participation of L. major Maf1 in mRNA post-transcriptional control, a role that, to the best of our knowledge, has not been described in other organisms.

Assessment of the antileishmanial activity of diallyl sulfide combined with meglumine antimoniate on Leishmania major: Molecular docking, in vitro, and animal model

Currently, no safe vaccine against leishmaniasis is available. So far, different control strategies against numerous reservoir hosts and biological vectors have not been environment-friendly and feasible. Hence, employing medicinal components and conventional drugs could be a promising approach to developing novel therapeutic alternatives. This study aimed to explore diallyl sulfide (DAS), a dynamic constituent of garlic, alone and in a mixture with meglumine antimoniate (MAT as standard drug) using in vitro and animal model experiments against Leishmania major stages. The binding affinity of DAS and four major defense elements of the immune system (iNOS, IFN-ɣ, IL-12, and TNF-α) was used to predict the predominant binding mode for molecular docking configurations. Herein, we conducted a broad range of experiments to monitor and assess DAS and MAT potential treatment outcomes. DAS, combined with MAT, displayed no cytotoxicity and employed a powerful anti-leishmanial activity, notably against the clinical stage. The function mechanism involved immunomodulation through the induction of Th1 cytokine phenotypes, triggering a high apoptotic profile, reactive oxygen species (ROS) production, and antioxidant enzymes. This combination significantly decreased cutaneous lesion diameter and parasite load in BALB/c mice. The histopathological findings performed the infiltration of inflammatory cells associated with T-lymphocytes, particularly CD4+ phenotypes, as determined by biochemical markers in alleviating the amastigote stage and improving the pathological changes in L. major infected BALB/c mice. Therefore, DAS and MAT deserve further advanced therapeutic development and should be considered as possible candidates for treating volunteer cases with cutaneous leishmaniasis in designing an upcoming clinical trial.

CD4+ and CD8+ T-cell multi-epitope chimeric protein associated with an MPLA adjuvant induce protective efficacy and long-term immunological memory for the immunoprophylaxis of American Tegumentary Leishmaniasis

American Tegumentary Leishmaniasis (ATL) is a disease of high severity and incidence in Brazil, in addition to being a worldwide concern in public health. Leishmania amazonensis is one of the etiological agents of ATL, and the inefficiency of control measures, associated with the high toxicity of the treatment and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present study proposes to elaborate a chimeric protein (rChiP), based on the fusion of multiple epitopes of CD4+/CD8+ T cells, identified in the immunoproteome of the parasites L. amazonensis and L. braziliensis. The designed chimeric protein was tested in the L. amazonensis murine model of infection using the following formulations: 25 μg of the rChiP in saline (rChiP group) and 25 μg of the rChiP plus 25 μg of MPLA-PHAD® (rChiP+MPLA group). After completing immunization, CD4+ and CD8+ T cells, stimulated with SLa-Antigen or rChiP, showed an increased production of nitric oxide and intracytoplasmic pro-inflammatory cytokines, in addition to the generation of central and effector memory T cells. rChiP and rChiP+MPLA formulations were able to promote an effective protection against L. amazonensis infection determined by a reduction in the development of skin lesions and lower parasitic burden. Reduction in the development of skin lesions and lower parasitic burden in the vaccinated groups were associated with an increase of nitrite, CD4+/CD8+IFN-γ+TNF-α+ and CD4+/CD8+CD44highCD62Lhigh/low T cells, IgGTotal, IgG2a, and lower rates of IgG1 and CD4+/CD8+IL-10+. This data suggests that proposed formulations could be considered potential tools to prevent ATL.

Photodynamic therapy in management of cutaneous leishmaniasis: A systematic review

This systematic review evaluated the efficacy and safety of photodynamic therapy (PDT) in the management of cutaneous leishmaniasis (CL). The electronic search for identification of relevant studies, adhered to the PICOS (Population, Intervention, Comparator, Outcomes and Study type) framework, was conducted through PubMed, Google scholar, Dimensions, X-mol, and Semantic Scholar till December 2023. All types of studies reporting PDT in the management of CL with no language restriction were included. Methodological quality appraised of the selected studies was performed using Jadad index. Of the 317 identified studies, 21 reported PDT for the treatment of CL lesions, consisting of two randomized controlled trials (RCTs), four single-center open study, one case series and 14 case reports. Collectively, these studies presented a total of 304 patients with ages ranging from 1 to 82 years, undergoing varying number of PDT sessions (3-28) and follow-up durations spanning 4 weeks to 24 months. The CL lesions predominantly manifested on the exposed body areas, such as face, limbs, neck, ear and nose, and characterized with the use of clinical variables, such as plaques, papules, erythema and ulceration. PDT protocols differed in the photosensitizer type, incubation time, light source characteristics (e.g., wavelength, output power, and energy density), duration of light illumination, number of PDT sessions and their respective frequencies. Treatment response was assessed through the clinical presentation (i.e., at the baseline and after PDT completion) or by the absence of Leishmania parasites. Adverse effects comprised of pain, burning and tingling sensation experienced during PDT, followed by erythema, pigmentation changes and edema post-treatment. This systematic review revealed that PDT is an efficacious and safe modality for the treatment of CL, with mild and transient side effects.

HIF-α signaling regulates the macrophage inflammatory response during Leishmania major infection

Cutaneous leishmaniasis (CL) contributes significantly to the global burden of neglected tropical diseases, with 12 million people currently infected with Leishmania parasites. CL encompasses a range of disease manifestations, from self-healing skin lesions to permanent disfigurations. Currently there is no vaccine available, and many patients are refractory to treatment, emphasizing the need for new therapeutic targets. Previous work demonstrated macrophage HIF-α-mediated lymphangiogenesis is necessary to achieve efficient wound resolution during murine L. major infection. Here, we investigate the role of macrophage HIF-α signaling independent of lymphangiogenesis. We sought to determine the relative contributions of the parasite and the host-mediated inflammation in the lesional microenvironment to myeloid HIF-α signaling. Because HIF-α activation can be detected in infected and bystander macrophages in leishmanial lesions, we hypothesize it is the host's inflammatory response and microenvironment, rather than the parasite, that triggers HIF-α activation. To address this, macrophages from mice with intact HIF-α signaling (LysM Cre ARNT f/+ ) or mice with deleted HIF-α signaling (LysM Cre ARNT f/f ) were subjected to RNASequencing after L. major infection and under pro-inflammatory stimulus. We report that L. major infection alone is enough to induce some minor HIF-α-dependent transcriptomic changes, while infection with L. major in combincation with pro-inflammatory stimuli induces numerous transcriptomic changes that are both dependent and independent of HIF-α signaling. Additionally, by coupling transcriptomic analysis with several pathway analyses, we found HIF-α suppresses pathways involved in protein translation during L. major infection in a pro-inflammatory environment. Together these findings show L. major induces a HIF-α-dependent transcriptomic program, but HIF-α only suppresses protein translation in a pro-inflammatory environment. Thus, this work indicates the host inflammatory response, rather than the parasite, largely contributes to myeloid HIF-α signaling during Leishmania infection.

Detection of Leishmania RNA Virus 2 (LRV2) among Clinical Isolates of Leishmania Major in Four Endemic Regions of Iran

PURPOSE

Leishmania RNA viruses (LRV) are double-stranded RNA viruses (dsRNA viruses) that play a role in the pathogenesis of Leishmania parasites. Cutaneous leishmaniasis (CL) is endemic in various parts of Iran. Our aimed was to investigate presence of LRV among the Leishmania major isolates in four endemic regions of Iran.

METHODS

In a cross-sectional study, we assessed the presence of LRV1 and LRV2 in 181 clinical isolates of L. major from four endemic cities in Iran using reverse transcription polymerase chain reaction (RT-PCR). After RNA extraction and cDNA synthesis, RT-PCR tests were conducted with LRV1 and LRV2 specific primers. Human beta-actin and kmp genes served as internal and external controls, respectively, and the Allele ID software was used to optimize melting curves.

RESULTS

LRV2 was detected in 27.6% (50 out of 181) of L. major isolates, while no LRV1 was found. We did not observe a statistically significant difference in the presence of LRV2 based on age group, number, or location of lesions.

CONCLUSION

This study confirms the presence of LRV2 in clinical isolates of L. major from endemic regions of Iran. Further researches with larger sample sizes is recommended to explore the association between LRV and clinical symptoms as well as treatment response.

The Interaction of Zinc as an Essential Trace Element with Leishmania Parasites: A Systematic Review

Background

The trace element of zinc (Zn) has shown great effectiveness in control of leishmaniasis infection. Hence, the present study conducted a systematic review of in vitro and in vivo studies evaluating the zinc effect in the treatment or prevention of leishmaniasis.

Materials and Methods

A systematic literature search was performed of all articles published in PubMed, SciELO, ScienceDirect, Scopus, Google Scholar, and Web of Science databases (1997-2023). The search terms were "zinc" OR "cutaneous leishmaniasis (CL)" OR "visceral leishmaniasis (VL)".

Results

Initial search yielded 89 citations, and 59 subjects were included. Data showed the zinc serum level in CL patients was lower than controls. Also, in vitro studies of zinc were more effective against L. tropica and L. major promastigotes compared to the amastigotes. Moreover, in vivo studies did not show destructive effects of zinc on the mammalian cell viability like macrophages. Furthermore, zinc depletion by specific chelators affected L. donovani survival and growth through promoting apoptosis and reactive oxygen species-dependent mechanisms.

Conclusion

The serum level determination of zinc could be useful for estimating the leishmaniasis pathophysiology. Environmentally or genetically determined increases in zinc levels might augment resístanse to CL. In contrast, zinc depletion using a zinc-specific chelator could be effective treatment of VL in endemic areas.

Synthesis and in vitro evaluation shows disquaramide compounds are a promising class of anti-leishmanial drugs

An increasing number of treatment failures with current pharmaceutics, as well as a lack of a vaccine, demonstrates the need to develop new treatment options for leishmaniasis. Herein, we describe the synthesis and in vitro analysis of 24 disquaramide compounds targeting the Leishmania major parasite. Of the compounds that were evaluated, six of them ( 13 , 19 , 20 , 22 , 24 , and 26 ) were capable of significantly decreasing the number of parasites by up to 42% compared to the control by day four. This demonstrates that disquaramides either impair parasite replication or have leishmancidal effects. Additionally, none of the disquaramide compounds tested displayed host cell cytotoxicity. These experiments provide evidence that disquaramides have the potential to be effective anti-leishmanial therapeutics.

Targeting Leishmania Promastigotes and Amastigotes Forms through Amino Acids and Peptides: A Promising Therapeutic Strategy

Millions of people worldwide are affected by leishmaniasis, caused by the Leishmania parasite. Effective treatment is challenging due to the biological complexity of the parasite, drug toxicity, and increasing resistance to conventional drugs. To combat this disease, the development of specific strategies to target and selectively eliminate the parasite is crucial. This Review highlights the importance of amino acids in the developmental stages of Leishmania as a factor determining whether the infection progresses or is suppressed. It also explores the use of peptides as alternatives in parasite control and the development of novel targeted treatments. While these strategies show promise for more effective and targeted treatment, further studies to address the remaining challenges are imperative.

Enhanced translational activity is linked to lymphatic endothelial cell activation in cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a significant public health problem leading to permanently disfiguring skin lesions caused by Leishmania parasites. Lesion severity stems from an excessive host inflammatory response that prevents healing. Here, we characterized the transcriptional and translational responses of lymphatic endothelial cells (LECs) during murine CL using historical single-cell RNA sequencing data combined with flow cytometry and in vivo puromycin incorporation to assess translational activity. We identified upregulation of antigen presentation pathways including MHC-I, MHC-II, and immunoproteasome transcripts in dermal LECs from Leishmania major -infected mice compared to naive controls. LECs also exhibited increased expression of guanylate binding proteins and interferon-inducible genes, indicative of immune activation. Moreover, our findings demonstrate that LECs in leishmanial lesions displayed heightened translational activity relative to LECs from uninflamed ears, and LEC translational activity was highest in activated LECs. Furthermore, LEC translational activity exceeded that of other cell types within the lesion microenvironment. Validating the transcriptomic data, LECs in lesions expressed elevated MHC-II and programmed death-ligand 1 (PDL-1), supporting their potential role in antigen presentation. Functional assays using DQ-OVA confirmed that LECs from leishmanial lesions efficiently uptake and process antigens, highlighting their capability as antigen presenting cells in the inflamed dermal microenvironment. Overall, our study reveals the activation status of LECs in leishmanial lesions, shedding light on their potential role in shaping local immunity and inflammation in a variety of skin diseases.

Unveiling the Enigmatic nature of six neglected Amazonian Leishmania (Viannia) species using the hamster model: Virulence, Histopathology and prospection of LRV1

American tegumentary leishmaniasis (ATL) is highly endemic in the Amazon basin and occurs in all South American countries, except Chile and Uruguay. Most Brazilian ATL cases are due to Leishmania (Viannia) braziliensis, however other neglected Amazonian species are being increasingly reported. They belong to the subgenus L. (Viannia) and information on suitable models to understand immunopathology are scarce. Here, we explored the use of the golden hamster Mesocricetus auratus and its macrophages as a model for L. (Viannia) species. We also studied the interaction of parasite glycoconjugates (LPGs and GIPLs) in murine macrophages. The following strains were used: L. (V.) braziliensis (MHOM/BR/2001/BA788), L. (V.) guyanensis (MHOM/BR/85/M9945), L. (V.) shawi (MHOM/BR/96/M15789), L. (V.) lindenbergi (MHOM/BR/98/M15733) and L. (V.) naiffi (MDAS/BR/79/M5533). In vivo infections were initiated by injecting parasites into the footpad and were followed up at 20- and 40-days PI. Parasites were mixed with salivary gland extract (SGE) from wild-captured Nyssomyia neivai prior to in vivo infections. Animals were euthanized for histopathological evaluation of the footpads, spleen, and liver. The parasite burden was evaluated in the skin and draining lymph nodes. In vitro infections used resident peritoneal macrophages and THP-1 monocytes infected with all species using a MOI (1:10). For biochemical studies, glycoconjugates (LPGs and GIPLs) were extracted, purified, and biochemically characterized using fluorophore-assisted carbohydrate electrophoresis (FACE). They were functionally evaluated after incubation with macrophages from C57BL/6 mice and knockouts (TLR2-/- and TLR4-/-) for nitric oxide (NO) and cytokine/chemokine production. All species, except L. (V.) guyanensis, failed to generate evident macroscopic lesions 40 days PI. The L. (V.) guyanensis lesions were swollen but did not ulcerate and microscopically were characterized by an intense inflammatory exudate. Despite the fact the other species did not produce visible skin lesions there was no or mild pro-inflammatory infiltration at the inoculation site and parasites survived in the hamster skin/lymph nodes and even visceralized. Although none of the species caused severe disease in the hamster, they differentially infected peritoneal macrophages in vitro. LPGs and GIPLs were able to differentially trigger NO and cytokine production via TLR2/TLR4 and TLR4, respectively. The presence of a sidechain in L. (V.) lainsoni LPG (type II) may be responsible for its higher proinflammatory activity. After Principal Component analyses using all phenotypic features, the clustering of L. (V.) lainsoni was separated from all the other L. (Viannia) species. We conclude that M. auratus was a suitable in vivo model for at least four dermotropic L. (Viannia) species. However, in vitro studies using peritoneal cells are a suitable alternative for understanding interactions of the six L. (Viannia) species used here. LRV1 presence was found in L. (V.) guyanensis and L. (V.) shawi with no apparent correlation with virulence in vitro and in vivo. Finally, parasite glycoconjugates were able to functionally trigger various innate immune responses in murine macrophages via TLRs consistent with their inflammatory profile in vivo.

The first evaluation of the in vitro effects of silver(I)-N-heterocyclic carbene complexes on Encephalitozoon intestinalis and Leishmania major promastigotes

Encephalitozoon intestinalis is an opportunistic microsporidian parasite that primarily infects immunocompromised individuals, such as those with HIV/AIDS or undergoing organ transplantation. Leishmaniasis is responsible for parasitic infections, particularly in developing countries. The disease has not been effectively controlled due to the lack of an effective vaccine and affordable treatment options. Current treatment options for E. intestinalis infection and leishmaniasis are limited and often associated with adverse side effects. There is no previous study in the literature on the antimicrosporidial activities of Ag(I)-N-heterocyclic carbene compounds. In this study, the in vitro antimicrosporidial activities of previously synthesized Ag(I)-N-heterocyclic carbene complexes were evaluated using E. intestinalis spores cultured in human renal epithelial cell lines (HEK-293). Inhibition of microsporidian replication was determined by spore counting. In addition, the effects of the compounds on Leishmania major promastigotes were assessed by measuring metabolic activity or cell viability using a tetrazolium reaction. Statistical analysis was performed to determine significant differences between treated and control groups. Our results showed that the growth of E. intestinalis and L. major promastigotes was inhibited by the tested compounds in a concentration-dependent manner. A significant decrease in parasite viability was observed at the highest concentrations. These results suggest that the compounds have potential anti-microsporidial and anti-leishmanial activity. Further research is required to elucidate the underlying mechanisms of action and to evaluate the efficacy of the compounds in animal models or clinical trials.

Altered co-stimulatory and inhibitory receptors on monocyte subsets in patients with visceral leishmaniasis

Visceral leishmaniasis (VL) is a neglected tropical disease caused by parasites from the Leishmania (L.) donovani complex. VL is characterised by uncontrolled parasite replication in spleen, liver and bone marrow, and by an impaired immune response and high systemic levels of inflammation. Monocytes have been poorly characterised in VL patients. The aim of this study was to evaluate the expression levels of markers involved in the regulation of T cell responses on different subsets of monocytes from the blood of VL patients and healthy non-endemic controls (HNEC). Monocytes can broadly be divided into three subsets: classical, intermediate and non-classical monocytes. Our results show that the percentages of all three subsets stayed similar at the time of VL diagnosis (ToD) and at the end of anti-leishmanial treatment (EoT). We first looked at co-stimulatory receptors: the expression levels of CD40 were significantly increased on classical and intermediate, but not non-classical monocytes, at ToD as compared to EoT and HNEC. CD80 expression levels were also increased on intermediate monocytes at ToD as compared to EoT and HNEC, and on classical monocytes only as compared to HNEC. The levels of CD86 were similar at EoT and ToD and in HNEC on classical and intermediate monocytes, but significantly higher at EoT on non-classical monocytes. We also looked at an inhibitory molecule, PD-L1. Our results show that the expression levels of PD-L1 were significantly higher on all three monocyte subsets at ToD as compared to HNEC, and to EoT on classical and intermediate monocytes. These results show that monocytes from the blood of VL patients upregulate both co-stimulatory and inhibitory receptors and that their expression levels are restored at EoT.

Galactokinase-like protein from Leishmania donovani: Biochemical and structural characterization of a recombinant protein

Leishmaniasis is a spectrum of conditions caused by infection with the protozoan Leishmania spp. parasites. Leishmaniasis is endemic in 98 countries around the world, and resistance to current anti-leishmanial drugs is rising. Our work has identified and characterised a previously unstudied galactokinase-like protein (GalK) in Leishmania donovani, which catalyses the MgATP-dependent phosphorylation of the C-1 hydroxyl group of d-galactose to galactose-1-phosphate. Here, we report the production of the catalytically active recombinant protein in E. coli, determination of its substrate specificity and kinetic constants, as well as analysis of its molecular envelope using in solution X-ray scattering. Our results reveal kinetic parameters in range with other galactokinases with an average apparent Km value of 76 μM for galactose, Vmax and apparent Kcat values with 4.46376 × 10-9 M/s and 0.021 s-1, respectively. Substantial substrate promiscuity was observed, with galactose being the preferred substrate, followed by mannose, fructose and GalNAc. LdGalK has a highly flexible protein structure suggestive of multiple conformational states in solution, which may be the key to its substrate promiscuity. Our data presents novel insights into the galactose salvaging pathway in Leishmania and positions this protein as a potential target for the development of pharmaceuticals seeking to interfere with parasite substrate metabolism.