Visceral leishmaniasis

Diagnosis of visceral and cutaneous leishmaniasis using loop-mediated isothermal amplification (LAMP) protocols: a systematic review and meta-analysis

Sensitive, reliable and fast diagnostic tools that are applicable in low-resource settings, at the point of care (PoC), are seen as crucial in the fight against visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). Addressing the need for a PoC test, several diagnostic tests, including serological and molecular methods, have been developed and evaluated in the past. One promising molecular method, already implemented for diagnosis of a range of diseases, is the loop-mediated isothermal amplification (LAMP) protocol. In this systematic review and meta-analysis, using a comprehensive search strategy, we focus on studies evaluating the performance of LAMP for the diagnosis of leishmaniasis in humans and other mammals such as dogs, compared with microscopy and/or any other molecular diagnostic method. A meta-analysis, pooling sensitivity and specificity rates and calculating areas under the curve (AUCs) in summary receiver operating characteristic (SROC) plots, was conducted on datasets extracted from studies, grouped by clinical condition and sample type. We found high sensitivity and specificity for LAMP when compared with microscopy and PCR using blood samples, with pooled estimate values of > 90% for all subgroups, corresponding to calculated AUC values > 0.96, except for LAMP compared to microscopy for diagnosis of CL. However, only a limited number of studies were truly comparable. Most of the observed heterogeneity is likely based on true differences between the studies rather than sampling error only. Due to simple readout methods and low laboratory equipment requirements for sample preparation compared to other molecular methods, LAMP is a promising candidate for a molecular (near-)PoC diagnostic method for VL and CL.

Leishmaniasis Beyond East Africa

Climate change is having a substantial impact on our environment and ecosystems and has altered the way humans live, access, and utilize resources with increased risk of zoonotic infectious disease encounters. As global temperatures continue to increase, they impact on public health, migration, food security and land conflict, and as new environments become favorable, exposure to disease carrying vectors. Increased forests or natural habitat clearance for land repurposing, urbanization, road building, and water management are related to an increase in emerging vector borne parasitic diseases. The East African region remains one of the most impacted regions globally for leishmaniasis, a vector borne disease that impacts significantly on the health, wellbeing and livelihoods of affected communities and for which a lack of reporting and control interventions hinder progress toward elimination of this neglected tropical disease. As our world continues to transform, both politically and climatically, it is essential that measures are put in place to improve surveillance and disease management with implementation of control measures, including vector control, especially in low- and middle-income countries that are expected to be most impacted by changes in climate. Only through effective management, now, can we be sufficiently resilient to preventing the inevitable spread of vectors into suitable habitat and expansion of the geographical range of leishmaniasis. This review offers a current perspective on Leishmaniasis as an endemic disease in East Africa and examines the potential of the recent emergence of Leishmania infection in hitherto unaffected regions to become a public health concern if no disease management is achieved.

PF-429242, a Subtilisin Inhibitor, Is Effective in vitro Against Leishmania infantum

PF-429242 is an inhibitor of subtilisin, an important protease found in Leishmania. However, studies regarding the effect of PF-429242 on Leishmania are scarce. In this work we evaluated the antileishmanial effect of PF-429242 against Leishmania infantum and the mechanism involved in the death of the parasite. PF-429242 had low toxicity against mammalian cells (peritoneal macrophages) (CC₅₀ = 189.07 μM) and presented activity against L. infantum promastigotes (IC₅₀ = 2.78 μM) and intracellular amastigotes (IC₅₀ = 14.07 μM), indicating selectivity toward the parasite. Transmission electron microscopy (TEM), as well as staining of L. infantum promastigotes with MitoTracker^® Red, rhodamine 123 and MitoSOX, revealed that the mitochondria was a potential target of PF-429242. In addition, PF-429242 caused an accumulation of neutral lipids in promastigotes, which was demonstrated by Nile Red staining and TEM, and induced oxidative stress (H₂DCFDA staining). Furthermore the formation of autophagic vacuoles in L. infantum promastigotes was observed by MDC staining and TEM. However, the killing induced by PF-429242 in L. infantum promastigotes appeared to be unrelated to apoptosis and/or necrosis as there was no phosphatidylserine externalization, DNA fragmentation or alterations in the permeability of the parasite plasma membrane, as assessed by annexin V-FITC, TUNEL and propidium iodide staining, respectively. The morphological and ultrastructural evaluation of the promastigotes by optical microscopy, scanning electron microscopy (SEM) and TEM, revealed the presence of parasites with flagellar defects. TEM analysis of the intracellular amastigotes indicated that mitochondrial damage and autophagy could also be involved in the death of these forms after treatment with PF-429242. In addition, PF-429242 treatment stimulated NO production from infected macrophage, but only at a high concentration (100 μM), as well as an increase of TNF levels after treatment with 10 μM of PF-429242. The compound did not stimulate ROS or IL-10 production. Together, these data highlight the antileishmanial potential of PF-429242, inducing several cellular alterations in the parasite, such as mitochondrial damage, neutral lipids accumulation, oxidative stress and autophagy which culminate in the death of L. infantum, as well as modulating host cellular responses that favor the development of an immune response against the parasite.

Modified solid lipid nanoparticles encapsulated with Amphotericin B and Paromomycin: an effective oral combination against experimental murine visceral leishmaniasis

The development of an effective oral therapeutics is an immediate need for the control and elimination of visceral leishmaniasis (VL). We exemplify the preparation and optimization of 2-hydroxypropyl-β-cyclodextrin (HPCD) modified solid lipid nanoparticles (SLNs) based oral combinational cargo system of Amphotericin B (AmB) and Paromomycin (PM) against murine VL. The emulsion solvent evaporation method was employed to prepare HPCD modified dual drug-loaded solid lipid nanoparticles (m-DDSLNs). The optimized formulations have a mean particle size of 141 ± 3.2 nm, a polydispersity index of 0.248 ± 0.11 and entrapment efficiency for AmB and PM was found to be 96% and 90% respectively. The morphology of m-DDSLNs was confirmed by scanning electron microscopy and transmission electron microscopy. The developed formulations revealed a sustained drug release profile upto 57% (AmB) and 21.5% (PM) within 72 h and were stable at both 4 °C and 25 °C during short term stability studies performed for 2 months. Confocal laser scanning microscopy confirmed complete cellular internalization of SLNs within 24 h of incubation. In vitro cytotoxicity study against J774A.1 macrophage cells confirmed the safety and biocompatibility of the developed formulations. Further, m-DDSLNs did not induce any hepatic/renal toxicities in Swiss albino mice. The in vitro simulated study was performed to check the stability in simulated gastric fluids and simulated intestinal fluids and the release was found almost negligible. The in vitro anti-leishmanial activity of m-DDSLNs (1 µg/ml) has shown a maximum percentage of inhibition (96.22%) on intra-cellular amastigote growth of L. donovani. m-DDSLNs (20 mg/kg × 5 days, p.o.) has significantly (P < 0.01) reduced the liver parasite burden as compared to miltefosine (3 mg/kg × 5 days, p.o.) in L. donovani-infected BALB/c mice. This work suggests that the superiority of as-prepared m-DDSLNs as a promising approach towards the oral delivery of anti-leishmanial drugs.

Evaluating the immunomodulatory responses of LdODC-derived MHC Class-II restricted peptides against VL

In a bid to develop a novel immunoprophylactic measure against visceral leishmaniasis (VL), MHC class-II-restricted epitopes of LdODC were identified by reverse vaccinology approach. Five consensus HLA-DRB1*0101-restricted epitopes were screened. The analysis revealed that the set of epitopes was presented by at least 54 diverse MHC class-II alleles. Based on in silico screening, followed by molecular dynamics simulation, population coverage analysis, and HLA cross-presentation ability, five best epitopes were evaluated. PBMCs isolated from treated VL subjects, when stimulated with synthetic peptide alone or as a cocktail of peptides, triggered a secretory IFN-γ, but not the IL-10 level. Support in this notion came from intracellular cytokine level with a considerable up-regulated IFN-γ produced by CD4⁺ T cells. Also, the enhanced IFN-γ seemed to be augmented with the activation of macrophages with prominent IL-12 production. Therefore, it can be concluded that the screened MHC class-II-restricted epitope hotspots derived from Leishmania ODC can trigger CD4⁺ T cells, which can skew macrophage functions towards protection. However, a detailed analysis can explore its potentiality as a vaccine candidate.

Epidemiological situations and control strategies of vector-borne diseases in Nepal during 1998–2016

Purpose

The purpose of this paper is to investigate epidemiology and control strategies of the four priority vector-borne diseases (VBDs) in Nepal, i.e. malaria, Kala-azar (visceral leishmaniasis), lymphatic filariasis (LF) and dengue fever/dengue hemorrhagic fever.

Design/methodology/approach

The study was a retrospective design to collect data during 1998–2016 from VBDs endemic districts of Nepal. All data were reviewed and epidemiological information of the four VBDs were analyzed.

Findings

The number of malaria cases during 1998–2016 of the 13 affected districts was declined from 8,498 to 991 cases with no record of deaths since 2012. The number of cases and deaths in the 12 kala-azar (visceral leishmaniasis) affected districts in 1998 was 1,409 and 42 cases, respectively, but was dramatically decreased in 2016 to 213 and 2 cases, respectively. LF cases of the 61 affected districts in 2011, 2014 and 2016 were 28,855, 30,000 and 33,517 cases, respectively. In total, 25 districts achieved elimination target and the remaining are expected to complete the needful cycles by 2018. Dengue incidence of the 31 affected districts during 2006–2015 was under controlled with reported cases of 642, 356 and 136 cases in 2013, 2014 and 2015, respectively, and only one death in 2015. Implementation of control strategies particularly disease management and community peoples’ awareness significantly reduced the cases and deaths of the target VBDs.

Practical implications

The results of this study clearly suggest that the current control strategies have been worked effectively. However, in particular of the VBDs, health education in communities in the endemic areas should be adopted for better community participation in the context of the primary health care approach and increase the effectiveness of disease control.

Originality/value

VBDs, i.e., malaria, kala-azar (visceral leishmaniasis), LF and dengue fever/dengue hemorrhagic fever, are major causes of morbidity and mortality in the least developed countries which include Nepal. Globalization of travel and trading, unplanned urbanization, environmental and climate change are having a significant impact on disease transmission. Therefore, the Ministry of Health of Nepal had brought some changes in strategies based on activities for disease control, vector control, preventive and preparedness for outbreak response. Consequently, the cases and deaths due to malaria, kala-azar (visceral leishmaniasis), lymphatic filaiasis and dengue fever/dengue hemorrhagic fever have been brought down markedly.

Modulation of TLR4 Sialylation Mediated by a Sialidase Neu1 and Impairment of Its Signaling in Leishmania donovani Infected Macrophages

Altered sialylation is generally maintained by a fine balance between sialidases and sialyltransferases, which plays an essential role during disease pathogenesis. TLR4 is a membrane-bound highly sialylated glycoprotein predominantly having α2,3-linked sialic acids. It is one of the most important client molecules in the anti-leishmanial innate immune arm. Here, we initiated a comprehensive study on the modulation of TLR4 sialylation in Leishmania donovani (L. d)-infected macrophages by a mammalian sialidase/neuraminidase-1 (Neu1) having substrate specificity toward α2,3-linked sialic acids. We observed reduced membrane-associated Neu1 with its decreased enzyme activity in infected macrophages. Moreover, we demonstrated reduced association of Neu1 with TLR4 leading to enhanced sialylation of TLR4 in these infected cells. Conversely, Neu1 over expression exhibited enhanced association of TLR4 with Neu1 leading to reduced sialylation which possibly linked to increased association of TLR4 with its downstream adaptor protein, MyD88. This, in turn, activated downstream MAP kinase signaling pathway, with enhanced nuclear translocation of NFκB that resulted in increased genetic and protein levels expression of Th1 cytokines and effector molecule nitric oxide secretion which ultimately leads to reduced parasite burden in macrophages. This was further validated by Neu1 silencing in infected macrophages which reversed such a situation. Such events strongly confirm the importance of Neu1 in modulation of TLR4 sialylation during parasite infection resulting in impairment of innate immune response. Furthermore, decreased membrane-bound Neu1 in infected macrophages could be attributed to its reduced tyrosine-phosphorylation as well as diminished association with cathepsin A. Both these phenomenon possibly play significant roles in inhibiting translocation of the sialidase from cytosol to membrane. Taken together, our study first time demonstrated impaired translocation of cytosolic Neu1 to the membrane of L. donovani-infected macrophages due to impaired phosphorylation of this enzyme. This novel finding establishes a link between enhanced α2,3-linked sialic acids on TLR4 and reduced membrane-bound Neu1 which plays a significant role for inhibiting downstream signaling to establish successful infection in the host cells.

Visceral Leishmaniasis Treatment Outcome and Associated Factors in Northern Ethiopia

BACKGROUND

Visceral leishmaniasis (VL), one of the most neglected tropical diseases, is placing a huge burden on Ethiopia. Despite the introduction of antileishmanial drugs, treatment outcomes across regions are variable due to drug resistance and other factors. Thus, understanding of VL treatment outcomes and its contributing factors helps decisions on treatment. However, the magnitude and the risk factors of poor treatment outcome are not well studied in our setting. Therefore, our study was designed to assess treatment outcomes and associated factors in patients with VL.

MATERIALS AND METHODS

A cross-sectional study was conducted in VL patients admitted between June 2016 and April 2018 to Ayder Comprehensive Specialized Hospital, Tigray, Northern Ethiopia. Data was collected through chart review of patient records. Logistic regression analysis was used to identify factors associated with poor treatment outcome.

RESULTS

A total of 148 VL patients were included in the study. The mean age (SD) of the patients was 32.86 (11.9) years; most of them (94.6%) were male patients. The proportion of poor treatment outcome was 12.1%. Multivariable logistic regression analysis showed that long duration of illness (> four weeks) (adjusted odds ratio (AOR): 6.1 [95% confidence interval (CI); 1.3-28.6], p=0.02) and concomitant tuberculosis (TB) infection (AOR 4.6 [95% CI; 1.1-19.1], p=0.04) were the independent predictors of poor treatment outcome.

CONCLUSIONS

Poor treatment outcome was observed in a considerable proportion of VL patients. Long duration of illness and coinfection with TB were associated with poor VL treatment outcome. Hence, early diagnosis and effective prompt treatment are important to improve treatment outcomes among VL patients. Special attention should also be given in the treatment of VL/TB coinfected patients in our setting.

Assessment of quality of life using WHOQOL-BREF in patients with visceral leishmaniasis

BACKGROUND

This study was aimed to assess the impact of quality of life using WHOQOL-BREF in patients with Visceral leishmaniasis (VL).

METHODS

A total of 95 VL cases and 95 healthy participants filled out the questionnaires. Data on socio-demographic aspects along with disease duration were collected. Data were compared using a t-test, analysis of variance and chi-square test.

RESULTS

VL patients experienced very high impact on their quality of life. Study cohort had male preponderance (72.63%). Majority (64.21%) were aged < 40 years. Longer disease duration was found to have significantly poor quality of life (p < 0.05). The physical domain was found to be most affected domains of quality of life (QOL). QOL was affected most in illiterate, married, housewife, rural population and patients with longer disease duration (p < 0.05). The psychological and environmental domains were significantly affected in > 40 years of age group married patients (p < 0.05).

CONCLUSIONS

VL significantly impaired the patients' (QOL) in all four domains (physical, psychological, social relationship and environmental). Physical domain was significantly the most affected domain.

Ruthenium-Clotrimazole complex has significant efficacy in the murine model of cutaneous leishmaniasis

In previous studies we reported a novel series of organometallic compounds, Ru^II complexed with clotrimazole, displaying potent trypanosomatid activity with unnoticeable toxicity toward normal mammalian cells. In view of the promising activity of Ru-clotrimazole complexes against Leishmania major (L. major), the present work sought to investigate the anti-leishmanial activity of the AM162 complex in the murine model of cutaneous leishmaniasis. In addition, to facilitate the design of new therapeutic strategies against this disease, we investigated the mode of action of two Ru-clotrimazole complexes in L. major promastigotes. Overall, we demonstrate that AM162 significantly reduced the lesion size in mice exposed to L. major infection. In addition, Ru-clotrimazole compounds are able to induce a mitochondrial dependent apoptotic-like death in the extracellular form of the parasite based on labeling of DNA fragments, mitochondrial depolarization, cell cycle alteration profile and plasma membrane phospholipid externalization. Our findings reveal a promising efficacy of the Ru-clotrimazole AM162 complex for the treatment of cutaneous leishmaniasis, as well as pro-apoptotic activity and thus guarantees further evaluation in pre-clinical studies.

Decentralized control of human visceral leishmaniasis in endemic urban areas of Brazil: a literature review

OBJECTIVES

Human migration and concomitant HIV infections are likely to bring about major changes in the epidemiology of some parasitic infections in Brazil. Human visceral leishmaniasis (HVL) control is particularly fraught with intricacies. It is against a backdrop of decentralized health care that the complex HVL control initiatives are brought to bear. This comprehensive review aims to explore the obstacles facing decentralized HVL control in urban endemic areas in Brazil.

METHOD

A literature search was carried out in December 2015 by means of three databases: MEDLINE, Google Scholar, and Web of Science.

RESULTS

Although there have been many strides that have been made in elucidating the eco-epidemiology of Leishmania infantum, which forms the underpinnings of the national control program, transmission risk factors for HVL are still insufficiently elucidated in urban settings. Decentralized HVL epidemiological surveillance and control for animal reservoirs and vectors may compromise sustainability. In addition, it may hamper timely human HVL case management. With the burgeoning of the HIV-HVL co-infection, the potential human transmission may be underestimated.

CONCLUSION

HVL is a disease with focal transmission at a critical juncture, which warrants that the bottlenecks facing the control program within contexts of decentralized healthcare systems be taken into account. In addition, HIV-driven HVL epidemics may substantially increase the transmission potential of the human reservoir. Calculating the basic reproductive number to fine-tune interventions will have to take into consideration the specific socio-economic development context.