Phase 4 pharmacovigilance trial of paromomycin injection for the treatment of visceral leishmaniasis in India

Assessment of the impact of implementation research on the Visceral Leishmaniasis (VL) elimination efforts in Nepal

Nepal, Bangladesh, and India signed a Memorandum of Understanding (MoU) in 2005 to eliminate visceral leishmaniasis (VL) as a public health problem from the Indian subcontinent by 2015. By 2021, the number of reported VL cases in these countries had declined by over 95% compared to 2007. This dramatic success was achieved through an elimination programme that implemented early case detection and effective treatment, vector control, disease surveillance, community participation, and operational research that underpinned these strategies. The experience offered an opportunity to assess the contribution of implementation research (IR) to VL elimination in Nepal. Desk review and a stakeholder workshop was conducted to analyse the relationship between key research outputs, major strategic decisions in the national VL elimination programme, and annual number of reported new cases over time between 2005 and 2023. The results indicated that the key decisions across the strategic elements, throughout the course of the elimination programme (such as on the most appropriate tools for diganostics and treatment, and on best strategies for case finding and vector management), were IR informed. IR itself responded dynamically to changes that resulted from interventions, addressing new questions that emerged from the field. Close collaboration between researchers, programme managers, and implementers in priority setting, design, conduct, and review of studies facilitated uptake of evidence into policy and programmatic activities. VL case numbers in Nepal are now reduced by 90% compared to 2005. Although direct attribution of disease decline to research outputs is difficult to establish, the Nepal experience demonstrates that IR can be a critical enabler for disease elimination. The lessons can potentially inform IR strategies in other countries with diseases targeted for elimination.

Recent Advances in Chemotherapeutics for Leishmaniasis: Importance of the Cellular Biochemistry of the Parasite and Its Molecular Interaction with the Host

Leishmaniasis, a category 1 neglected protozoan disease caused by a kinetoplastid pathogen called Leishmania, is transmitted through dipteran insect vectors (phlebotomine, sand flies) in three main clinical forms: fatal visceral leishmaniasis, self-healing cutaneous leishmaniasis, and mucocutaneous leishmaniasis. Generic pentavalent antimonials have long been the drug of choice against leishmaniasis; however, their success is plagued with limitations such as drug resistance and severe side effects, which makes them redundant as frontline therapy for endemic visceral leishmaniasis. Alternative therapeutic regimens based on amphotericin B, miltefosine, and paromomycin have also been approved. Due to the unavailability of human vaccines, first-line chemotherapies such as pentavalent antimonials, pentamidine, and amphotericin B are the only options to treat infected individuals. The higher toxicity, adverse effects, and perceived cost of these pharmaceutics, coupled with the emergence of parasite resistance and disease relapse, makes it urgent to identify new, rationalized drug targets for the improvement in disease management and palliative care for patients. This has become an emergent need and more relevant due to the lack of information on validated molecular resistance markers for the monitoring and surveillance of changes in drug sensitivity and resistance. The present study reviewed the recent advances in chemotherapeutic regimens by targeting novel drugs using several strategies including bioinformatics to gain new insight into leishmaniasis. Leishmania has unique enzymes and biochemical pathways that are distinct from those of its mammalian hosts. In light of the limited number of available antileishmanial drugs, the identification of novel drug targets and studying the molecular and cellular aspects of these drugs in the parasite and its host is critical to design specific inhibitors targeting and controlling the parasite. The biochemical characterization of unique Leishmania-specific enzymes can be used as tools to read through possible drug targets. In this review, we discuss relevant metabolic pathways and novel drugs that are unique, essential, and linked to the survival of the parasite based on bioinformatics and cellular and biochemical analyses.

Insights into the drug screening approaches in leishmaniasis

Leishmaniasis, a tropically neglected disease, is responsible for the high mortality and morbidity ratio in poverty-stricken areas. Currently, no vaccine is available for the complete cure of the disease. Current chemotherapeutic regimens face the limitations of drug resistance and toxicity concerns indicating a great need to develop better chemotherapeutic leads that are orally administrable, potent, non-toxic, and cost-effective. The anti-leishmanial drug discovery process accelerated the desire for large-scale drug screening assays and high-throughput screening (HTS) technology to identify new chemo-types that can be used as potential drug molecules to control infection. Using the HTS approach, about one million compounds can be screened daily within the shortest possible time for biological activity using automation tools, miniaturized assay formats, and large-scale data analysis. Classical and modern in vitro screening assays have led to the progression of active compounds further to ex vivo and in vivo studies. In the present review, we emphasized on the HTS approaches employed in the leishmanial drug discovery program. Recent in vitro screening assays are widely explored to discover new chemical scaffolds. Developing appropriate experimental animal models and their related techniques is necessary to understand the pathophysiological processes and disease host responses, paving the way for unraveling novel therapies against leishmaniasis.

Genome-wide analysis reveals allelic variation and chromosome copy number variation in paromomycin-resistant Leishmania donovani

In the absence of adequate diagnosis and treatment, leishmaniasis remains a major public health concern on a global scale. Drug resistance remains a key obstacle in controlling and eliminating visceral leishmaniasis. The therapeutic gap due to lack of target-specific medicine and vaccine can be minimized by obtaining parasite's genomic information. This study compared whole-genome sequence of paromomycin-resistant parasite (K133PMM) developed through in vitro adaptation and selection with sensitive Leishmania clinical isolate (K133WT). We found a large number of upstream and intergenic gene variations in K133PMM. There were 259 single nucleotide polymorphisms (SNPs), 187 insertion-deletion (InDels), and 546 copy number variations (CNVs) identified. Most of the genomic variations were found in the gene's upstream and non-coding regions. Ploidy estimation revealed chromosome 5 in tetrasomy and 6, 9, and 12 in trisomy, uniquely in K133PMM. These contain the genes for protein degradation, parasite motility, autophagy, cell cycle maintenance, and drug efflux membrane transporters. Furthermore, we also observed reduction in ploidy of chromosomes 15, 20, and 23, in the resistant parasite containing mostly the genes for hypothetical proteins and membrane transporters. We chronicled correlated genomic conversion and aneuploidy in parasites and hypothesize that this led to rapid evolutionary changes in response to drug induced pressure, which causes them to become resistant.

Tackling Drug Resistance and Other Causes of Treatment Failure in Leishmaniasis

Leishmaniasis is a tropical infectious disease caused by the protozoan Leishmania parasite. The disease is transmitted by female sand flies and, depending on the infecting parasite species, causes either cutaneous (stigmatizing skin lesions), mucocutaneous (destruction of mucous membranes of nose, mouth and throat) or visceral disease (a potentially fatal infection of liver, spleen and bone marrow). Although more than 1 million new cases occur annually, chemotherapeutic options are limited and their efficacy is jeopardized by increasing treatment failure rates and growing drug resistance. To delay the emergence of resistance to existing and new drugs, elucidating the currently unknown causes of variable drug efficacy (related to parasite susceptibility, host immunity and drug pharmacokinetics) and improved use of genotypic and phenotypic tools to define, measure and monitor resistance in the field are critical. This review highlights recent progress in our understanding of drug action and resistance in Leishmania, ongoing challenges (including setbacks related to the COVID-19 pandemic) and provides an overview of possible strategies to tackle this public health challenge.

Antileishmanial Drug Discovery and Development: Time to Reset the Model?

Leishmaniasis is a vector-borne parasitic disease caused by Leishmania species. The disease affects humans and animals, particularly dogs, provoking cutaneous, mucocutaneous, or visceral processes depending on the Leishmania sp. and the host immune response. No vaccine for humans is available, and the control relies mainly on chemotherapy. However, currently used drugs are old, some are toxic, and the safer presentations are largely unaffordable by the most severely affected human populations. Moreover, its efficacy has shortcomings, and it has been challenged by the growing reports of resistance and therapeutic failure. This manuscript presents an overview of the currently used drugs, the prevailing model to develop new antileishmanial drugs and its low efficiency, and the impact of deconstruction of the drug pipeline on the high failure rate of potential drugs. To improve the predictive value of preclinical research in the chemotherapy of leishmaniasis, several proposals are presented to circumvent critical hurdles-namely, lack of common goals of collaborative research, particularly in public-private partnership; fragmented efforts; use of inadequate surrogate models, especially for in vivo trials; shortcomings of target product profile (TPP) guides.

Advancement in leishmaniasis diagnosis and therapeutics: An update

Leishmaniasis is regarded as a neglected tropical disease by World Health Organization (WHO) and is ranked next to malaria as the deadliest protozoan disease. The primary causative agents of the disease comprise of diverse leishmanial species sharing clinical features ranging from skin abrasions to lethal infection in the visceral organs. As several Leishmania species are involved in infection, the role of accurate diagnosis becomes pivotal in adding new dimensions to anti-leishmanial therapy. Diagnostic methods must be fast, reliable, easy to perform, highly sensitive, and specific to differentiate among similar parasitic diseases. Herein, we present the conventional and recent approaches impended for the disease diagnosis and their sensitivity, specificity, and clinical application in parasite detection. Furthermore, we have also elaborated various new methods to cure leishmaniasis, which include host-directed therapies, drug repurposing, nanotechnology, and combinational therapy. This review addresses novel techniques and innovations in leishmaniasis, which can aid in unraveling new strategies to fight against the deadly infection.

Visceral Leishmaniasis in pregnancy and vertical transmission: A systematic literature review on the therapeutic orphans

Background

Reports on the occurrence and outcome of Visceral Leishmaniasis (VL) in pregnant women is rare in published literature. The occurrence of VL in pregnancy is not systematically captured and cases are rarely followed-up to detect consequences of infection and treatment on the pregnant women and foetus.

Methods

A review of all published literature was undertaken to identify cases of VL infections among pregnant women by searching the following database: Ovid MEDLINE; Ovid Embase; Cochrane Database of Systematic Reviews; Cochrane Central Register of Controlled Trials; World Health Organization Global Index Medicus: LILACS (Americas); IMSEAR (South-East Asia); IMEMR (Eastern Mediterranean); WPRIM (Western Pacific); ClinicalTrials.gov; and the WHO International Clinical Trials Registry Platform. Selection criteria included any clinical reports describing the disease in pregnancy or vertical transmission of the disease in humans. Articles meeting pre-specified inclusion criteria and non-primary research articles such as textbook, chapters, letters, retrospective case description, or reports of accidental inclusion in trials were also considered.

Results

The systematic literature search identified 272 unique articles of which 54 records were included in this review; a further 18 records were identified from additional search of the references of the included studies or from personal communication leading to a total of 72 records (71 case reports/case series; 1 retrospective cohort study; 1926–2020) describing 451 cases of VL in pregnant women. The disease was detected during pregnancy in 398 (88.2%), retrospectively confirmed after giving birth in 52 (11.5%), and the time of identification was not clear in 1 (0.2%). Of the 398 pregnant women whose infection was identified during pregnancy, 346 (86.9%) received a treatment, 3 (0.8%) were untreated, and the treatment status was not clear in the remaining 49 (12.3%). Of 346 pregnant women, Liposomal amphotericin B (L-AmB) was administered in 202 (58.4%) and pentavalent antimony (PA) in 93 (26.9%). Outcomes were reported in 176 pregnant women treated with L-AmB with 4 (2.3%) reports of maternal deaths, 5 (2.8%) miscarriages, and 2 (1.1%) foetal death/stillbirth. For PA, outcomes were reported in 88 of whom 4 (4.5%) died, 24 (27.3%) had spontaneous abortion, 2 (2.3%) had miscarriages. A total of 26 cases of confirmed, probable or suspected cases of vertical transmission were identified with a median detection time of 6 months (range: 0–18 months).

Conclusions

Outcomes of VL treatment during pregnancy is rarely reported and under-researched. The reported articles were mainly case reports and case series and the reported information was often incomplete. From the studies identified, it is difficult to derive a generalisable information on outcomes for pregnant women and babies, although reported data favours the usage of liposomal amphotericin B for the treatment of VL in pregnant women.

Visceral Leishmaniasis (VL) is a neglected tropical disease with an estimated incidence of 50,000 to 90,000 cases in 2019. Women who are susceptible to becoming pregnant or those who are pregnant and lactating are regularly excluded from clinical studies of VL. A specific concern of public health relevance is the little knowledge of the consequences of VL and its treatment on the mother and the foetus. We did a systematic review of all published literature with an overarching aim of identifying cases of VL in pregnancy and assessing the risk-benefit balance of antileishmanial treatment to the pregnant women and the child. We identified a total of 72 records (1926–2020) describing 451 VL cases in pregnant women. In 398, infection was identified during pregnancy of whom 202 received Liposomal Amphotericin B (L-AmB) and 93 received pentavalent antimony (PA). In studies that reported maternal outcomes, reports of maternal death abortion/spontaneous abortion, and miscarriages were proportionally lower among those who received L-AmB compared to PA (no formal test of significance carried out). A total of 26 cases of confirmed, probable or suspected cases of vertical transmission were identified and the median time to detection was 6 months (range: 0–18 months). Our review brings together scattered observations of VL in pregnant women in the clinical literature and clearly highlights that the disease in pregnancy is under-reported and under-studied. The collated evidence derived mainly from case reports and case series indicate that L-AmB has a favourable safety profile than the antimony regimen and should be the preferred treatment for VL during pregnancy.

Efficacy and Safety of Paromomycin for Visceral Leishmaniasis: A Systematic Review

Visceral leishmaniasis, also known as kala-azar is one of the most commonly neglected tropical diseases affecting a large number of rural and resource-limited people in South Asia, Africa, and South America. Paromomycin, an aminoglycoside drug, is frequently used for the treatment of visceral leishmaniasis. Despite limited therapies for visceral leishmaniasis and emerging drug resistance, a proper review on the action of paromomycin for kala-azar is lacking. This systematic review aims to look for the efficacy and safety aspects of paromomycin for the treatment of visceral leishmaniasis.

Gender disparity in cases enrolled in clinical trials of visceral leishmaniasis: A systematic review and meta-analysis

BACKGROUND

A higher caseload of visceral leishmaniasis (VL) has been observed among males in community-based surveys. We carried out this review to investigate how the observed disparity in gender distribution is reflected in clinical trials of antileishmanial therapies.

METHODS

We identified relevant studies by searching a database of all published clinical trials in VL from 1980 through 2019 indexed in the Infectious Diseases Data Observatory (IDDO) VL clinical trials library. The proportion of male participants enrolled in studies eligible for inclusion in this review were extracted and combined using random effects meta-analysis of proportion. Results were expressed as percentages and presented with respective 95% confidence intervals (95% CIs). Heterogeneity was quantified using I2 statistics and sub-group meta-analyses were carried out to explore the sources of heterogeneity.

RESULTS

We identified 135 published studies (1980-2019; 32,177 patients) with 68.0% [95% CI: 65.9%-70.0%; I2 = 92.6%] of the enrolled participants being males. The corresponding estimates were 67.6% [95% CI: 65.5%-69.7%; n = 91 trials; I2 = 90.5%; 24,218 patients] in studies conducted in the Indian sub-continent and 74.1% [95% CI: 68.4%-79.1%; n = 24 trials; I2 = 94.4%; 6,716 patients] in studies from Eastern Africa. The proportion of male participants was 57.9% [95% CI: 54.2%-61.5%] in studies enrolling children aged <15 years, 78.2% [95% CI: 66.0%-86.9%] in studies that enrolled adults (≥15 years), and 68.1% [95% CI: 65.9%-70.0%] in studies that enrolled patients of all ages. There was a trend for decreased proportions of males enrolled over time: 77.1% [95% CI: 70.2%-82.8%; 1356 patients] in studies published prior to the 1990s whereas 64.3% [95% CI: 60.3%-68.2%; 15,611 patients] in studies published on or after 2010. In studies that allowed the inclusion of patients with HIV co-infections, 76.5% [95% CI: 63.8%-85.9%; 5,123 patients] were males and the corresponding estimate was 64.0% [95% CI: 61.4%-66.5% 17,500 patients] in studies which excluded patients with HIV co-infections.

CONCLUSIONS

Two-thirds of the participants enrolled in clinical studies in VL conducted in the past 40 years were males, though the imbalance was less in children and in more recent trials. VL treatment guidelines are informed by the knowledge of treatment outcomes from a population that is heavily skewed towards adult males. Investigators planning future studies should consider this fact and ensure approaches for more gender-balanced inclusion.

Recent advances and new strategies on leishmaniasis treatment

Leishmaniasis is one of the most important tropical neglected diseases according to the World Health Organization. Even after more than a century, we still have few drugs for the disease therapy and their great toxicity and side effects put in check the treatment control program around the world. Moreover, the emergence of strains resistant to conventional drugs, co-infections such as HIV/Leishmania spp., the small therapeutic arsenal (pentavalent antimonials, amphotericin B and formulations, and miltefosine), and the low investment for the discovery/development of new drugs force researchers and world health agencies to seek new strategies to combat and control this important neglected disease. In this context, the aim of this review is to summarize new advances and new strategies used on leishmaniasis therapy addressing alternative and innovative treatment paths such as physical and local/topical therapies, combination or multi-drug uses, immunomodulation, drug repurposing, and the nanotechnology-based drug delivery systems.Key points• The treatment of leishmaniasis is a challenge for global health agencies.• Toxicity, side effects, reduced therapeutic arsenal, and drug resistance are the main problems.• New strategies and recent advances on leishmaniasis treatment are urgent.• Immunomodulators, nanotechnology, and drug repurposing are the future of leishmaniasis treatment.

Paromomycin-loaded mannosylated chitosan nanoparticles: Synthesis, characterization and targeted drug delivery against leishmaniasis

Cutaneous leishmaniasis is the most common form of leishmaniasis caused by different species of Leishmania parasites. The emergence of resistance, toxicity, long term treatment, high cost of the current drugs, and intracellular nature of the parasite are the major difficulties for the treatment of leishmaniasis. Although the therapeutic effect of paromomycin (PM) on leishmaniasisLeishmania parasite). PM-loaded into mannosylated CS (MCS) nanoparticles using dextran (PM-MCS-dex-NPs) was prepared by ionic gelation and then characterized. The particle size and Zeta potential of PM-MCS-dex-NPs were obtained as 246 nm and + 31 mV, respectively. Mannosylation of CS was qualitatively evaluated by Fourier-transform infrared spectroscopy and quantitatively measured by CHNO elemental analysis; also, a mannosylation level of 17% (w) was attained. Encapsulation efficiency (EE), drug release profile, and THP-1 cell uptake potential were determined. A value of 83.5% for EE and a higher release rate in acidic media were achieved. THP-1 cell uptake level of PM-MCS-dex-NPs after 6 h was ˜2.8 and ˜3.9 times of non-mannosylated CS nanoparticles (PM-CS-dexIn vitroGlucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 1846 ± 158, 1234 ± 93, 784 ± 52 and 2714 ± 126 μg mL^-1Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 105.0 ± 14.0, 169.5 ± 9.8, 65.8 ± 7.3 and 17.8 ± 1.0 μg mL^-1Glucantim, PM-CS-dex-NPs and PM-MCS-dexGlucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs at a typical concentration of 20 μg mL^-1 were 71.78, 69.94, 83.14 and 33.41%, respectively. While the effect of PM-CS-dex-NPs was more salient on amastigotes, PM-MCS-dex-NPs effectively affected both stages of the parasite, especially the amastigote one. This indicated that the mannosylated formulation acts as a targeted delivery system. The findings of this study revealed that this novel targeted formulation represented a strong anti-leishmanial activity.

Paromomycin-loaded mannosylated chitosan nanoparticles: Synthesis, characterization and targeted drug delivery against leishmaniasis

Cutaneous leishmaniasis is the most common form of leishmaniasis caused by different species of Leishmania parasites. The emergence of resistance, toxicity, long term treatment, high cost of the current drugs, and intracellular nature of the parasite are the major difficulties for the treatment of leishmaniasis. Although the therapeutic effect of paromomycin (PM) on leishmaniasis has been investigated in different studies, it has a low oral absorption and short half-life, leading to a decreased drug efficacy. Therefore, new and targeted carriers with no such problems are needed. In the present study, PM was loaded into chitosan (CS) nanoparticles accompanied by targeting to macrophages (as the host of Leishmania parasite). PM-loaded into mannosylated CS (MCS) nanoparticles using dextran (PM-MCS-dex-NPs) was prepared by ionic gelation and then characterized. The particle size and zeta potential of PM-MCS-dex-NPs were obtained as 246 nm and +31 mV, respectively. Mannosylation of CS was qualitatively evaluated by Fourier-transform infrared spectroscopy and quantitatively measured by CHNO elemental analysis; also, a mannosylation level of 17% (w) was attained. Encapsulation efficiency (EE), drug release profile, and THP-1 cell uptake potential were determined. A value of 83.5% for EE and a higher release rate in acidic media were achieved. THP-1 cell uptake level of PM-MCS-dex-NPs after 6 h was ˜2.8 and ˜3.9 times of non-mannosylated CS nanoparticles (PM-CS-dex-NPs) and PM aqueous solution, respectively. In vitro cell cytotoxicity and promastigote and amastigote viabilities were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Half-maximal inhibitory concentration values toward the THP-1 cells for PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 1846 ± 158, 1234 ± 93, 784 ± 52 and 2714 ± 126 μg mL^-1, respectively. Half-maximal inhibitory concentration values toward the promastigotes for PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 105.0 ± 14.0, 169.5 ± 9.8, 65.8 ± 7.3 and 17.8 ± 1.0 μg mL^-1, respectively. Selectivity (therapeutic) indices for PM aqueous solution, Glucantim, PM-CS-dex-NPs and PM-MCS-dex-NPs after 48 h were obtained as 24.6, 17.5, 3.7 and 214, respectively. The parasite burden in THP-1 cells after 48 h treatment with PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs at a typical concentration of 20 μg mL^-1 were 71.78, 69.94, 83.14 and 33.41%, respectively. While the effect of PM-CS-dex-NPs was more salient on amastigotes, PM-MCS-dex-NPs effectively affected both stages of the parasite, especially the amastigote one. This indicated that the mannosylated formulation acts as a targeted delivery system. The findings of this study revealed that this novel targeted formulation represented a strong anti-leishmanial activity.

Emerging role of amiodarone and dronedarone, as antiarrhythmic drugs, in treatment of leishmaniasis

Leishmaniasis is a group of human and animal diseases causing 20,000-40,000 annual deaths and its etiological agents belong to the Leishmania genus. The most current treatment against leishmaniasis is chemotherapy. Pentavalent antimonials such as glucantime and pentostam have been administrated as the first-line drugs in treatment of various forms of leishmaniasis. The second-line drugs such as amphotericin B, liposomal amphotericin B, miltefosine, pentamidine, azole drugs and paromomycin are used in resistant cases to pentavalent antimonials. Because of drawbacks of the first-line and second-line drugs including adverse side effects on different organs, increasing resistance, high cost, need to hospitalization and long-term treatment, it is necessary to find an alternative drug for leishmaniasis treatment. Several investigations have reported the effectiveness of amiodarone, the most commonly used antiarrhythmic drug, against fungi, Trypanosomes and Leishmania spp. in vitro, in vivo and clinical conditions. Moreover, the beneficial effects of dronedarone, amiodarone analogues, against Trypanosoma cruzi and Leishmania mexicana have recently been demonstrated and such treatment regimens resulted in lower side effects. The anti- leishmanial and anti- trypanosomal effectiveness of amiodarone and dronedarone has been attributed to destabilization of intracellular Ca²⁺ homeostasis, inhibition of sterol biosynthesis and collapse of mitochondrial membrane potential. Because of relative low cost, excellent pharmacokinetic properties, easy accessibility and beneficial effects of amiodarone and dronedarone on leishmaniasis, they are proper candidates to replace the current drugs used in leishmaniasis treatment.

Using focused pharmacovigilance for ensuring patient safety against antileishmanial drugs in Bangladesh's National Kala-azar Elimination Programme

Background

Adverse effects of antileishmanial drugs can affect patients’ quality of life and adherence to therapy for visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL). In Bangladesh, there are 26 treatment centers that manage leishmaniasis cases coming from 100 endemic upazilas (subdistricts) of 26 districts (these include VL, PKDL, treatment failure, and relapse VL and cutaneous leishmaniasis cases). This study aimed to investigate the feasibility of using focused pharmacovigilance for VL (VLPV) in Bangladesh’s National Kala-azar Elimination Programme for the early detection and prevention of expected and unexpected adverse drug reactions (ADRs).

Methods

This activity has been going on since December 2014. Activity area includes secondary public hospital or Upazila health complex (UHC) in hundred sub districts and Surya Kanta Kala-azar Research Center (SKKRC) in Mymensingh District, a specialized center for management of complicated VL and PKDL cases. Communicable Disease Control (CDC) of the Directorate General of Health Services (DGHS) assigned twenty five of hundred UHCs and SKKRC (total 26) as treatment centers depending on their suitable geographical location. This was implemented for better management of VL cases with Liposomal Amphotericin B (AmBisome®) to ensure patient convenience and proper utilization of this expensive donated drug. A VLPV expert committee and a UHC VLPV team were established, an operational manual and pharmacovigilance report forms were developed, training and refresher training of health personnel took place at UHCs and at the central level, collected information such as patient data including demographics, treatment history and response, adverse events were analyzed. This report includes information for the period from December 2014 to December 2016.

Results

From December 2014 to December 2016, 1327 leishmaniasis patients were treated and 1066 (80%) were available for VLPV. Out of these, 57, 33, 9, and 1% were new VL, PKDL, VL relapse, and other cases, respectively. Liposomal amphotericin B was mostly used (82%) for case management, followed by miltefosine (20%) and paromomycin (3%). Out of the 1066 patients, 26% experienced ADRs. The most frequent ADR was fever (17%, 176/1066), followed by vomiting (5%, 51/1066). Thirteen serious adverse events (SAEs) (eight deaths and five unexpected SAEs) were observed. The expert committee assessed that three of the deaths and all unexpected SAEs were possibly related to treatment. Out of the five unexpected SAEs, four were miltefosine-induced ophthalmic complications and the other was an AmBisome®-induced avascular necrosis of the nasal alae. The Directorate General of the Drug Administration entered the ADRs into the World Health Organization Uppsala Monitoring Centre (WHO-UMC) VigiFlow database.

Conclusions

This study found that VLPV through NKEP is feasible and should be continued as a routine activity into the public health system of Bangladesh to ensure patient safety against anti-leishmanial drugs.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0461-0) contains supplementary material, which is available to authorized users.

Transcriptome profiling identifies genes/pathways associated with experimental resistance to paromomycin in Leishmania donovani

Widespread resistance towards antimony and reports of relapses following miltefosine treatment has severely affected the management of visceral leishmaniasis (VL) in the Indian subcontinent. Paromomycin (PMM), an aminoglycoside antibiotic, has been licensed for VL treatment in India in 2007. Although its use is still restricted in the field, unraveling the molecular mechanism of resistance towards PMM is the key to preserve the drug. In this study, PMM resistant lines were selected up to 100 μM of PMM in three distinct field isolates of Leishmania donovani at promastigote stage. The resistance induced at promastigote level was also evident in amastigotes which showed 6 fold decreases in PMM susceptibility. Comparative transcriptome profiling of PMM resistant (PMM-R) and the corresponding PMM sensitive (PMM-S) parasites revealed modulated expression of 500 genes (1.5 fold cut off) in PMM-R parasites. Selected genes were validated for their modulated expression by quantitative real-time PCR. Functional classification and pathway analysis of modulated genes indicated probable adaptations in drug resistant lines which included a) reduced oxidative phosphorylation; b) increased glycosomal succinate fermentation and substrate level phosphorylation; c) dependency on lipids and amino acids for energy generation; d) reduced DNA synthesis and increased DNA damage repair and e) decreased protein synthesis and degradation. Interestingly, PMM-R parasites showed a marked increase in PMM susceptibility in presence of verapamil and amlodipine, antagonists of Ca2+ channel that are also modulators of ABC transporters. Moreover, infection of macrophages by PMM-R parasites led to modulated nitric oxide (NO) levels while reactive oxygen species (ROS) level remained unaltered. The present study highlights the putative mechanisms of PMM resistance in Leishmania.

The enemy within: Targeting host-parasite interaction for antileishmanial drug discovery

The state of antileishmanial chemotherapy is strongly compromised by the emergence of drug-resistant Leishmania. The evolution of drug-resistant phenotypes has been linked to the parasites’ intrinsic genome instability, with frequent gene and chromosome amplifications causing fitness gains that are directly selected by environmental factors, including the presence of antileishmanial drugs. Thus, even though the unique eukaryotic biology of Leishmania and its dependence on parasite-specific virulence factors provide valid opportunities for chemotherapeutical intervention, all strategies that target the parasite in a direct fashion are likely prone to select for resistance. Here, we review the current state of antileishmanial chemotherapy and discuss the limitations of ongoing drug discovery efforts. We finally propose new strategies that target Leishmania viability indirectly via mechanisms of host–parasite interaction, including parasite-released ectokinases and host epigenetic regulation, which modulate host cell signaling and transcriptional regulation, respectively, to establish permissive conditions for intracellular Leishmania survival.

Recent developments and future prospects in the treatment of visceral leishmaniasis

Limited therapeutic options in visceral leishmaniasis (VL) make the treatment of this neglected disease very challenging. In addition to this, long treatment duration and toxic adverse effects make it even more difficult. With no effective vaccine available to date, treatment of VL is based only on chemotherapy. In the Indian subcontinent, a single dose of liposomal amphotericin B (L-AmB) and multidrug therapy (L-AmB + miltefosine, L-AmB + paromomycin [PM], or miltefosine + PM) are the treatments of choice for VL. In East Africa, however, combination therapy of pentavalent antimonials (Sb(v)) and PM remains the treatment of choice, and in the Mediterranean region and South America, L-AmB is the recommended drug. Fexinidazole and PA-824 are new promising drugs which have shown encouraging results in preclinical studies.

Current challenges in treatment options for visceral leishmaniasis in India: a public health perspective

Visceral leishmaniasis (VL) is a serious parasitic disease causing considerable mortality and major disability in the Indian subcontinent. It is most neglected tropical disease, particularly in terms of new drug development for the lack of financial returns. An elimination campaign has been running in India since 2005 that aim to reduce the incidence of VL to below 1 per 10,000 people at sub-district level. One of the major components in this endeavor is reducing transmission through early case detection followed by complete treatment. Substantial progress has been made during the recent years in the area of VL treatment, and the VL elimination initiatives have already saved many lives by deploying them effectively in the endemic areas. However, many challenges remain to be overcome including availability of drugs, cost of treatment (drugs and hospitalization), efficacy, adverse effects, and growing parasite resistance. Therefore, better emphasis on implementation research is urgently needed to determine how best to deliver existing interventions with available anti-leishmanial drugs. It is essential that the new treatment options become truly accessible, not simply available in endemic areas so that they may promote healing and save lives. In this review, we highlight the recent advancement and challenges in current treatment options for VL in disease endemic area, and discuss the possible strategies to improve the therapeutic outcome.

Effectiveness Study of Paromomycin IM Injection (PMIM) for the Treatment of Visceral Leishmaniasis (VL) in Bangladesh

Background

This study was conducted in Bangladeshi patients in an outpatient setting to support registration of Paromomycin Intramuscular Injection (PMIM) as a low-cost treatment option in Bangladesh.

Methodology

This Phase IIIb, open-label, multi-center, single-arm trial assessed the efficacy and safety of PMIM administered at 11 mg/kg (paromomycin base) intramuscularly once daily for 21 consecutive days to children and adults with VL in a rural outpatient setting in Bangladesh. Patients ≥5 and ≤55 years were eligible if they had signs and symptoms of VL (intermittent fever, weight loss/decreased appetite, and enlarged spleen), positive rK39 test, and were living in VL-endemic areas. Compliance was the percentage of enrolled patients who received 21 daily injections over no more than 22 days. Efficacy was evaluated by initial clinical response, defined as resolution of fever and reduction of splenomegaly at end of treatment, and final clinical response, defined as the absence of new clinical signs and symptoms of VL 6 months after end of treatment. Safety was assessed by evaluation of adverse events.

Principal Findings

A total of 120 subjects (49% pediatric) were enrolled. Treatment compliance was 98.3%. Initial clinical response in the Intent-to-Treat population was 98.3%, and final clinical response 6 months after end of treatment was 94.2%. Of the 119 subjects who received ≥1 dose of PMIM, 28.6% reported at least one adverse event. Injection site pain was the most commonly reported adverse event. Reversible renal impairment and/or hearing loss were reported in 2 subjects.

Conclusions/Significance

PMIM was an effective and safe treatment for VL in Bangladesh. The short treatment duration and lower cost of PMIM compared with other treatment options may make this drug a preferred treatment to be investigated as part of a combination therapy regimen. This study supports the registration of PMIM for use in government health facilities in Bangladesh.

Trial Registration

ClinicalTrials.gov identifier: NCT01328457

Effective and safe therapies for visceral leishmaniasis (VL), also known as kala-azar, at an affordable cost are urgently needed in Bangladesh. Although sodium stibogluconate, miltefosine, and paromomycin are included in the National Essential Drug List for VL, only miltefosine is currently registered in Bangladesh. Paromomycin is a low-cost drug that was demonstrated to be an efficacious and safe treatment for VL in endemic areas of India, which led to approval of paromomycin IM injection (PMIM) for the treatment of VL in India in 2006 and inclusion of PMIM in the WHO Essential Medicines List in 2007. A subsequent Phase IV trial in India revealed a similarly high efficacy and safety profile coupled with high treatment compliance in a rural outpatient setting. We confirmed the effectiveness, safety, and high compliance of PMIM when used in an outpatient setting in Bangladesh. This study supports the registration of PMIM as a low-cost treatment option for VL in Bangladesh.

An update on pharmacotherapy for leishmaniasis

INTRODUCTION

Leishmaniasis broadly manifests as visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis. The treatment of leishmaniasis is challenging and the armamentarium of drugs is small, duration of treatment is long, and most drugs are toxic.

AREAS COVERED

A literature search on treatment of leishmaniasis was done on PubMed. Single dose of liposomal amphotericin B (L-AmB) and multidrug therapy (L-AmB + miltefosine, L-AmB + paromomycin (PM), or miltefosine + PM) are the treatment of choice for VL in the Indian subcontinent. A 17-day combination therapy of pentavalent antimonials (Sb(v)) and PM remains the treatment of choice for East African VL. L-AmB at a total dose of 18 - 21 mg/kg is the recommended regimen for VL in the Mediterranean region and South America. Treatment of CL should be decided by the severity of clinical lesions, etiological species and its potential to develop into mucosal leishmaniasis.

EXPERT OPINION

There is an urgent need to implement a single-dose L-AmB or combination therapy in the Indian subcontinent. Shorter and more acceptable regimens are needed for the treatment of post - kala-azar dermal leishmaniasis. Combination therapy with newer drugs needs to be tested in Africa. Due to the toxicity of systemic therapy, a trend toward local treatment for New World CL is preferred in patients without risk of mucosal disease.

Efficacy and safety of amphotericin B emulsion versus liposomal formulation in Indian patients with visceral leishmaniasis: a randomized, open-label study

Background

India is home to 60% of the total global visceral leishmaniasis (VL) population. Use of long-term oral (e.g. miltefosine) and parenteral drugs, considered the mainstay for treatment of VL, is now faced with increased resistance, decreased efficacy, low compliance and safety issues. The authors evaluated the efficacy and safety of an alternate treatment option, i.e. single infusion of preformed amphotericin B (AmB) lipid emulsion (ABLE) in comparison with that of liposomal formulation (LAmB).

Methods

In this multicentric, open-label study, 500 patients with VL were randomly assigned in a 3∶1 ratio to receive 15 mg/kg single infusion of either ABLE (N = 376) or LAmB (N = 124). Initial cure (Day 30/45), clinical improvement (Day 30) and long term definitive cure (Day 180) were assessed.

Findings

A total of 326 (86.7%) patients in the ABLE group and 122 (98.4%) patients in the LAmB group completed the study. Initial cure was achieved by 95.9% of patients in the ABLE group compared to 100% in the LAmB group (p = 0.028; 95% CI: −0.0663, −0.0150). Clinical improvement was comparable between treatments (ABLE: 98.9% vs. LAmB: 98.4%). Definitive cure was achieved in 85.9% with ABLE compared to 98.4% with LAmB. Infusion-related pyrexia (37.2% vs. 32.3%) and chills (18.4% vs. 18.5%) were comparable between ABLE and LAmB, respectively. Treatment-related serious adverse events were fewer in ABLE (0.3%) compared to LAmB (1.6%). Two deaths occurred in the ABLE group, of which one was probably related to the study drug. Nephrotoxicity and hepatotoxicity was not observed in either group.

Conclusions

ABLE 15 mg/kg single infusion had favorable efficacy and was well tolerated. Considering the demographic profile of the population in this region, a single dose treatment offers advantages in terms of compliance, cost and applicability.

Trial Registration

www.clinicaltrials.govNCT00876824

Visceral leishmaniasis (VL) is highly prevalent in northeastern India, particularly the state of Bihar and its bordering areas with Bangladesh and Nepal. The current standards of treatment, namely, miltefosine (oral) and pentavalent antimonials (parenteral) have long treatment durations and are faced with increasing resistance, decreased efficacy, low compliance and safety issues. In this regard, lipid formulations of amphotericin B (AmB) have become an attractive treatment option due to their high efficacy, shorter treatment regimens and favorable safety profiles. This Phase III study evaluated the efficacy and safety of preformed AmB lipid emulsion (ABLE) versus liposomal AmB (LAmB) (both 15 mg/kg single dose infusions) in the treatment of VL. ABLE showed favorable efficacy measured in terms of initial cure at Day 30/45, and overall clinical improvement. ABLE was well tolerated and its adverse event profile was consistent with previously documented findings. Based on the favorable efficacy and safety profile of ABLE, and considering the demographic profile of the population in the endemic region, a single dose treatment may offer advantages in terms of compliance, cost and applicability.

Therapeutic options for visceral leishmaniasis

Visceral leishmaniasis (VL), also known as Kala-Azar, is a disseminated protozoal infection caused principally by Leishmania donovani and Leishmania infantum (known as Leishmania chagasi in South America). The therapeutic options for VL are diverse and depend on different factors, such as the geographical area of the infection, development of resistance to habitual treatments, HIV co-infection, malnourishment and other concomitant infections. This article provides an exhaustive review of the literature regarding studies published on the treatment of VL, and gives therapeutic recommendations stratified according to their level of evidence, the species of Leishmania implicated and the geographical location of the infection.

The lost hope of elimination of Kala-azar (visceral leishmaniasis) by 2010 and cyclic occurrence of its outbreak in India, blame falls on vector control practices or co-infection with human immunodeficiency virus or therapeutic modalities?

The Kala-azar/visceral leishmaniasis (VL) turns epidemic form once in every 15 years in the endemic regions of Indian subcontinent. The goal of elimination of Kala-azar from India by 2010 was lost despite paramount efforts taken by the Government of India and World Health Organization and Regional Office for South East Asia. The main objective of this review was to elucidate the possible reason for the failure of Kala-azar elimination program and to suggest possible remedial measures to achieve the goal in future. The annual numbers of VL cases and deaths recorded in India since 1977 were plotted on a graph, to see if the temporal trends could be associated with changes in the vector control practices or co-infection with human immunodeficiency virus (HIV) or therapeutic modalities used against VL. The VL cases flares up whenever the effect of dichlorodiphenyltrichloroethane (DDT) diminished after the withdrawal of spray. The fading effectiveness was clearly correlated with an increasing number of VL cases. Therapeutic modalities were found to be highly correlating with VL mortality not with VL morbidity. The diminishing efficacy of first and second line drugs and the introduction of new drugs and drugs combination were responsible for ups and downs in the VL mortality. The VL mortality is constantly declining since 1993, but cases started increasing from 2003 to 2007 and then recently again from 2010 to 2011. This shows a serious lacuna in the vector control practices applied. The extent of HIV co-infection did not show any correlation with number/trend of VL cases or death over the study period. It is concluded that, by strict vector control practices, the VL cases can be reduced and by applying proper therapeutic strategies, the VL mortality can be reduced. HIV-VL co-infection does not seem to be in a worried stage.

Elucidation of cellular mechanisms involved in experimental paromomycin resistance in Leishmania donovani

Leishmania donovani is the causative agent of the potentially fatal disease visceral leishmaniasis (VL). Chemotherapeutic options available to treat VL are limited and often face parasite resistance, inconsistent efficacy, and toxic side effects. Paromomycin (PMM) was recently introduced to treat VL as a monotherapy and in combination therapy. It is vital to understand the mechanisms of PMM resistance to safeguard the drug. In the present study, we utilized experimentally generated PMM-resistant L. donovani to elucidate the mechanisms of resistance and parasite biology. We found increased membrane fluidity accompanied by decreased intracellular drug accumulation in the PMM-resistant parasites. There were marked increases in gene expression of ATP-binding cassette (ABC) transporters (MDR1 and MRPA) and protein phosphatase 2A that evince increased drug efflux. Further, evaluation of parasite tolerance toward host leishmanicidal mechanisms revealed PMM-resistant parasites as being more tolerant to nitrosative stress at the promastigote and amastigote stages. The PMM-resistant parasites also predicted a better survival capacity, as indicated by resistance to complement-mediated lysis and increased stimulation of host interleukin-10 (IL-10) expression. The susceptibilities of PMM-resistant isolates to other antileishmanial agents (sodium antimony gluconate and miltefosine) remained unchanged. The data implicated the roles of altered membrane fluidity, decreased drug accumulation, increased expression of ABC transporters, and greater tolerance of parasites to host defense mechanisms in conferring PMM resistance in Leishmania.

[Leishmania epidemiology, diagnosis, chemotherapy and vaccination approaches in the international network of Pasteur Institutes]

Protozoan parasites of the genus Leishmania generate severe human diseases termed leishmaniases. Due to their frequency and the severity of certain clinical forms, these diseases represent a major public health problem and limit the economic growth in various developing countries. The presence of Pasteur Institutes in countries with endemic leishmaniasis has provided important incentives to develop a strong public health agenda in the Pasteur scientific community with respect to this important disease. A concerted effort is now coordinated through the recently created LeishRIIP platform (www.leishriip.org), which aims to identify synergies and complementary expertise between the eleven members of the international network of Pasteur Institutes working on various aspects of the disease including epidemiology, diagnosis, chemotherapy and vaccination.

Developments in diagnosis and treatment of visceral leishmaniasis during the last decade and future prospects

Human visceral leishmaniasis (VL) continues to be a life-threatening neglected tropical disease, with close to 200 million people at risk of infection globally. Epidemics and resurgence of VL are associated with negligence by the policy makers, economic decline and population movements. Control of the disease is hampered by the lack of proficient vaccination, rapid diagnosis in a field setting and severe side effects of current drug therapies. The diagnosis of VL relied largely on invasive techniques of detecting parasites in splenic and bone marrow aspirates. rK39 and PCR, despite problems related to varying sensitivities and specificities and field adaptability, respectively, are considered the best options for VL diagnosis today. No single therapy of VL currently offers satisfactory efficacy along with safety. The field of VL research only recently shifted toward actively identifying new drugs for safe and affordable treatment. Oral miltefosine and safe AmBisome along with better use of amphotericin B have been rapidly implemented in the last decade. A combination therapy will substantially reduce the required dose and duration of drug administration and reduce the chance of the development of resistance. In addition, identification of asymptomatic cases, vector control and treatment of post-kala-azar dermal leishmaniasis would allow new perspectives in VL control and management.

Identification of the molecular attributes required for aminoglycoside activity against Leishmania

Leishmaniasis, a parasitic disease caused by protozoa of the genus Leishmania, affects millions of people worldwide. Aminoglycosides are mostly known as highly potent, broad-spectrum antibiotics that exert their antibacterial activity by selectively targeting the decoding A site of the bacterial ribosome, leading to aberrant protein synthesis. Recently, some aminoglycosides have been clinically approved and are currently used worldwide for the treatment of leishmaniasis; however the molecular details by which aminoglycosides induce their deleterious effect on Leishmaina is still rather obscure. Based on high conservation of the decoding site among all kingdoms, it is assumed that the putative binding site of these agents in Leishmania is the ribosomal A site. However, although recent X-ray crystal structures of the bacterial ribosome in complex with aminoglycosides shed light on the mechanism of aminoglycosides action as antibiotics, no such data are presently available regarding their binding site in Leishmania. We present crystal structures of two different aminoglycoside molecules bound to a model of the Leishmania ribosomal A site: Geneticin (G418), a potent aminoglycoside for the treatment of leishmaniasis at a 2.65-Å resolution, and Apramycin, shown to be a strong binder to the leishmanial ribosome lacking an antileishmanial activity at 1.4-Å resolution. The structural data, coupled with in vitro inhibition measurements on two strains of Leishmania, provide insight as to the source of the difference in inhibitory activity of different Aminoglycosides. The combined structural and physiological data sets the ground for rational design of new, and more specific, aminoglycoside derivatives as potential therapeutic agents against leishmaniasis.

Leishmaniasis: an update of current pharmacotherapy

INTRODUCTION

Leishmaniasis broadly manifests as visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL). The treatment of VL is challenging. The duration of treatment is long, and drugs are toxic thereby needing monitoring and hospitalization.

AREAS COVERED

Novel therapies such as single dose of liposomal amphotericin B (L-AmB) and multidrug therapy are important breakthrough for VL in the Indian subcontinent and have been recommended as the treatment of choice in this region. African Leishmania donovani is less susceptible to L-AmB, miltefosine and paromomycin as compared to the Indian strains, and the treatment of choice remains a 17-day combination therapy of pentavalent antimonials (SB(v)) and paromomycin. L-AmB at a total dose of 18 - 21 mg/kg is the recommended regimen in the Mediterranean region and South America. It is also the treatment of choice for HIV-VL coinfection. Treatment of CL should be decided by the clinical lesions, etiological species and its potential to develop into mucosal leishmaniasis. A literature search on treatment of leishmaniasis was done on PubMed and through Google.

EXPERT OPINION

There is an urgent need for exploratory studies with short course, highly efficient regimens such as single dose L-AmB or combination therapy for all the endemic regions of VL. Shorter and more acceptable regimens are needed for the treatment of post-kala-azar dermal leishmaniasis. Treatment of CL remains one of the neglected areas of leishmaniasis as data are scarce and drawn from uncontrolled studies.

Interest in paromomycin for the treatment of visceral leishmaniasis (kala-azar)

Leishmaniasis is an important vector-borne disease, and it is classified as one of the most important tropical fly-borne infections. This disease can cause two types of clinical manifestations: cutaneous forms and visceral forms. Visceral leishmaniasis, which is also called kala-azar, is a very serious infection that can be fatal. The management of visceral leishmaniasis requires informed diagnostic and therapeutic approaches. Continuous research and development regarding the treatment of visceral leishmaniasis had led to many improvements. Paromomycin is a relatively new antibiotic drug that has been used for the treatment of visceral leishmaniasis for several years. This article reviews and discusses the use of paromomycin for visceral leishmaniasis therapy.

Drug susceptibility in Leishmania isolates following miltefosine treatment in cases of visceral leishmaniasis and post kala-azar dermal leishmaniasis

Background

With widespread resistance to antimonials in Visceral Leishmaniasis (VL) in the Indian subcontinent, Miltefosine (MIL) has been introduced as the first line therapy. Surveillance of MIL susceptibility in natural populations of Leishmania donovani is vital to preserve it and support the VL elimination program.

Methodology and Principal Findings

We measured in vitro susceptibility towards MIL and paromomycin (PMM) in L. donovani isolated from VL and PKDL, pre- and post-treatment cases, using an amastigote-macrophage model. MIL susceptibility of post-treatment isolates from cured VL cases (n = 13, mean IC₅₀±SD = 2.43±1.44 µM), was comparable (p>0.05) whereas that from relapses (n = 3, mean IC₅₀ = 4.72±1.99 µM) was significantly higher (p = 0.04) to that of the pre-treatment group (n = 6, mean IC₅₀ = 1.86±0.75 µM). In PKDL, post-treatment isolates (n = 3, mean IC₅₀ = 16.13±2.64 µM) exhibited significantly lower susceptibility (p = 0.03) than pre-treatment isolates (n = 5, mean IC₅₀ = 8.63±0.94 µM). Overall, PKDL isolates (n = 8, mean IC₅₀ = 11.45±4.19 µM) exhibited significantly higher tolerance (p<0.0001) to MIL than VL isolates (n = 22, mean IC₅₀ = 2.58±1.58 µM). Point mutations in the miltefosine transporter (LdMT) and its beta subunit (LdRos3) genes previously reported in parasites with experimentally induced MIL resistance were not present in the clinical isolates. Further, the mRNA expression profile of these genes was comparable in the pre- and post-treatment isolates. Parasite isolates from VL and PKDL cases were uniformly susceptible to PMM with respective mean IC₅₀ = 7.05±2.24 µM and 6.18±1.51 µM.

Conclusion

The in vitro susceptibility of VL isolates remained unchanged at the end of MIL treatment; however, isolates from relapsed VL and PKDL cases had lower susceptibility than the pre-treatment isolates. PKDL isolates were more tolerant towards MIL in comparison with VL isolates. All parasite isolates were uniformly susceptible to PMM. Mutations in the LdMT and LdRos3 genes as well as changes in the expression of these genes previously correlated with experimental resistance to MIL could not be verified for the field isolates.

Resistance to antimonials has emerged as a major hurdle to the treatment and control of VL and led to the introduction of Miltefosine as first line treatment in the Indian subcontinent. MIL is an oral drug with a long half-life, and it is feared that resistance may emerge rapidly, threatening control efforts under the VL elimination program. There is an urgent need for monitoring treatment efficacy and emergence of drug resistance in the field. In a set of VL/PKDL cases recruited for MIL treatment, we observed comparable drug susceptibility in pre- and post-treatment isolates from cured VL patients while MIL susceptibility was significantly reduced in isolates from VL relapse and PKDL cases. The PKDL isolates showed higher tolerance to MIL as compared to VL isolates. Both VL and PKDL isolates were uniformly susceptible to PMM. MIL transporter genes LdMT/LdRos3 were previously reported as potential resistance markers in strains in which MIL resistance was experimentally induced. The point mutations and the down-regulated expression of these transporters observed in vitro could, however, not be verified in natural populations of parasites. LdMT/LdRos3 genes therefore, do not appear to be suitable markers so far for monitoring drug susceptibility in clinical leishmanial isolates.