Long term outcomes and prognostics of visceral leishmaniasis in HIV infected patients with use of pentamidine as secondary prophylaxis based on CD4 level: a prospective cohort study in Ethiopia

Background

The long-term treatment outcome of visceral leishmaniasis (VL) patients with HIV co-infection is complicated by a high rate of relapse, especially when the CD4 count is low. Although use of secondary prophylaxis is recommended, it is not routinely practiced and data on its effectiveness and safety are limited.

Methods

A prospective cohort study was conducted in Northwest Ethiopia from August 2014 to August 2017 (NCT02011958). HIV-VL patients were followed for up to 12 months. Patients with CD4 cell counts below 200/μL at the end of VL treatment received pentamidine prophylaxis starting one month after parasitological cure, while those with CD4 count ≥200 cells/μL were followed without secondary prophylaxis. Compliance, safety and relapse-free survival, using Kaplan-Meier analysis methods to account for variable time at risk, were summarised. Risk factors for relapse or death were analysed.

Results

Fifty-four HIV patients were followed. The probability of relapse-free survival at one year was 50% (95% confidence interval [CI]: 35–63%): 53% (30–71%) in 22 patients with CD4 ≥200 cells/μL without pentamidine prophylaxis and 46% (26–63%) in 29 with CD4 <200 cells/μL who started pentamidine. Three patients with CD4 <200 cells/μL did not start pentamidine. Amongst those with CD4 ≥200 cells/μL, VL relapse was an independent risk factor for subsequent relapse or death (adjusted rate ratio: 5.42, 95% CI: 1.1–25.8). Except for one case of renal failure which was considered possibly related to pentamidine, there were no drug-related safety concerns.

Conclusion

The relapse-free survival rate for VL patients with HIV was low. Relapse-free survival of patients with CD4 count <200cells/μL given pentamidine secondary prophylaxis appeared to be comparable to patients with a CD4 count ≥200 cells/μL not given prophylaxis. Patients with relapsed VL are at higher risk for subsequent relapse and should be considered a priority for secondary prophylaxis, irrespective of their CD4 count.

Achieving parasitological cure at the end of visceral leishmaniasis (VL) treatment in HIV co-infected patients does not assure definitive cure, as the disease will recur within a year in many patients. In this cohort study, the probability of relapse-free survival at one-year was 50% in all patients. The use of monthly pentamidine infusion for those with lower CD4 counts (<200 cells/μL) at the time of VL cure appeared to result in a comparable relapse-free survival rate to those patients with higher CD4 count (≥200 cells/μL) who did not receive secondary prophylaxis. On the other hand, patients with a history of previous VL treatment (VL relapse) remained at high risk of relapse despite achieving CD4 count ≥200 cells/μL at the end of the VL treatment. While all VL patients with HIV co-infection may benefit from secondary prophylaxis, those with CD4 <200 cells/μL and previous history of treatment should be prioritized for secondary prophylaxis. New modalities for prevention of VL relapse in HIV patients should also be explored.

A chronic bioluminescent model of experimental visceral leishmaniasis for accelerating drug discovery

Background

Visceral leishmaniasis is a neglected parasitic disease with no vaccine available and its pharmacological treatment is reduced to a limited number of unsafe drugs. The scarce readiness of new antileishmanial drugs is even more alarming when relapses appear or the occurrence of hard-to-treat resistant strains is detected. In addition, there is a gap between the initial and late stages of drug development, which greatly delays the selection of leads for subsequent studies.

Methodology/Principal findings

In order to address these issues, we have generated a red-shifted luminescent Leishmania infantum strain that enables long-term monitoring of parasite burden in individual animals with an in vivo limit of detection of 10⁶ intracellular amastigotes 48 h postinfection. For this purpose, we have injected intravenously different infective doses (10⁴—5x10⁸) of metacyclic parasites in susceptible mouse models and the disease was monitored from initial times to 21 weeks postinfection. The emission of light from the target organs demonstrated the sequential parasite colonization of liver, spleen and bone marrow. When miltefosine was used as proof-of-concept, spleen weight parasite burden and bioluminescence values decreased significantly.

Conclusions

In vivo bioimaging using a red-shifted modified Leishmania infantum strain allows the appraisal of acute and chronic stage of infection, being a powerful tool for accelerating drug development against visceral leishmaniasis during both stages and helping to bridge the gap between early discovery process and subsequent drug development.

Visceral leishmaniasis is a neglected disease that poses a significant threat to impoverished human populations of low-income countries. Due to the unavailability of vaccines, pharmacological treatment is the only approach to control the disease that otherwise can be lethal. To date, drug management in endemic regions is based on combinations of a handful of mostly unsafe drugs, where the emergence of resistant strains is an additional problem. To accelerate the discovery of new drug entities, several gaps from the early discovery of a compound to its public use, should be filled. One of these gaps is the need of a rapid go/no-go testing system for compounds based on robust preclinical models. Here, we propose a new long-term model of murine visceral leishmaniasis using in vivo bioluminescent imaging. For this purpose, a red-shifted bioluminescent Leishmania infantum strain was engineered. This strain has allowed the appraisal of the disease in individual animals and the monitoring of parasite colonization in liver, spleen and bone marrow. As proof of concept of this platform, mice were infected with the transgenic L. infantum strain treated with a standard schedule of miltefosine, the only oral drug available against Leishmania parasites. Bioluminescence and parasite load in the target organs were compared showing a good correlation. Our findings provide a robust and reproducible tool for drug discovery in a chronic model of murine visceral leishmaniasis.

Identification of GSK3186899/DDD853651 as a Preclinical Development Candidate for the Treatment of Visceral Leishmaniasis

The leishmaniases are diseases that affect millions of people across the world, in particular visceral leishmaniasis (VL) which is fatal unless treated. Current standard of care for VL suffers from multiple issues and there is a limited pipeline of new candidate drugs. As such, there is a clear unmet medical need to identify new treatments. This paper describes the optimization of a phenotypic hit against Leishmania donovani, the major causative organism of VL. The key challenges were to balance solubility and metabolic stability while maintaining potency. Herein, strategies to address these shortcomings and enhance efficacy are discussed, culminating in the discovery of preclinical development candidate GSK3186899/DDD853651 (1) for VL.

The safety and efficacy of miltefosine in the long-term treatment of post-kala-azar dermal leishmaniasis in South Asia - A review and meta-analysis

BACKGROUND

Miltefosine (MF) is the only oral drug available for treatment of visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL). Although the drug is effective and well tolerated in treatment of VL, the efficacy and safety of MF for longer treatment durations (>28 days) in PKDL remains unclear. This study provides an overview of the current knowledge about safety and efficacy of long treatment courses with MF in PKDL, as a strategy in the VL elimination in South Asia.

METHODOLOGY/PRINCIPAL FINDINGS

Literature was searched systematically for articles investigating MF treatment in PKDL. A meta-analysis included eight studies (total 324 PKDL patients) to estimate the efficacy of MF in longer treatment regimens (range 6-16 weeks). We found a per-protocol (PP) initial cure rate of 95.2% (95%CI 89.6-100.8) and a PP definite cure rate of 90% (95%CI 81.6-96.3). Descriptive analysis showed that 20% of patients experienced adverse events, which mostly had an onset in the first week of treatment and were likely to get more severe after four weeks of treatment. Gastrointestinal (GI) side effects such as vomiting, nausea, diarrhoea, and abdominal pain were most common.

CONCLUSIONS/SIGNIFICANCE

Longer treatment regimens with MF are effective in PKDL patients in India, however with the caveat that the efficacy has recently been observed to decline. GI side effects are frequent, although mostly mild or moderate. However, on the basis of limited data, we cannot conclude that longer MF treatment regimens are safe. Moreover, VL and PKDL pharmacovigilance studies indicate a risk for serious adverse events, questioning the safety of MF. The provision of safer treatment regimens for PKDL patients are therefore recommended. Until these regimens are identified, it should be considered to halt the use of MF monotherapy for PKDL in order to preserve the drug's efficacy.

Eliminating visceral leishmaniasis in South Asia: the road ahead

Suman Rijal and colleagues highlight lessons from a regional collaboration to eliminate visceral leishmaniasis and identify priorities for the post-elimination plan

A randomized trial of AmBisome monotherapy and AmBisome and miltefosine combination to treat visceral leishmaniasis in HIV co-infected patients in Ethiopia

Background

Visceral leishmaniasis (VL) in human immunodeficiency virus (HIV) co-infected patients requires special case management. AmBisome monotherapy at 40 mg/kg is recommended by the World Health Organization. The objective of the study was to assess if a combination of a lower dose of AmBisome with miltefosine would show acceptable efficacy at the end of treatment.

Methodology/Principal findings

An open-label, non-comparative randomized trial of AmBisome (30 mg/kg) with miltefosine (100 mg/day for 28 days), and AmBisome monotherapy (40 mg/kg) was conducted in Ethiopian VL patients co-infected with HIV (NCT02011958). A sequential design was used with a triangular continuation region. The primary outcome was parasite clearance at day 29, after the first round of treatment. Patients with clinical improvement but without parasite clearance at day 29 received a second round of the allocated treatment. Efficacy was evaluated again at day 58, after completion of treatment.

Recruitment was stopped after inclusion of 19 and 39 patients in monotherapy and combination arms respectively, as per pre-specified stopping rules. At D29, intention-to-treat efficacy in the AmBisome arm was 70% (95% CI 45–87%) in the unadjusted analysis, and 50% (95% CI 27–73%) in the adjusted analysis, while in the combination arm, it was 81% (95% CI 67–90%) and 67% (95% CI 48–82%) respectively. At D58, the adjusted efficacy was 55% (95% CI 32–78%) in the monotherapy arm, and 88% (95% CI 79–98%) in the combination arm.

No major safety concerns related to the study medication were identified. Ten SAEs were observed within the treatment period, and 4 deaths unrelated to the study medication.

Conclusions/Significance

The extended treatment strategy with the combination regimen showed the highest documented efficacy in HIV-VL patients; these results support a recommendation of this regimen as first-line treatment strategy for HIV-VL patients in eastern Africa.

Trial registration number

www.clinicaltrials.govNCT02011958.

Visceral Leishmaniasis is a complex parasitological disease and is particularly challenging to treat in patients coinfected with human immunodeficiency virus (HIV). Antimonial drugs used in first-line treatments for immunocompetent patients in eastern Africa are more toxic in immunocompromised patients. In 2010, a WHO expert committee recommended a lipid formulation of amphotericin B as first line treatment for HIV/VL co-infected patients, based on a single clinical trial conducted in Spain and empirical information obtained from scattered case reports using AmBisome (liposomal amphotericin B). In addition, Médecins Sans Frontières began a compassionate use regimen combining AmBisome and miltefosine a in a treatment centre in Northwest Ethiopia with encouraging results. Here, we report the results of a trial to assess the efficacy and safety of both the currently internationally recommended treatment of AmBisome monotherapy and the new AmBisome-miltefosine combination regimen, in Ethiopian patients. The results of this trial show that one course of treatment with either regimen could be insufficient to clear parasites in a high proportion of patients and that an extended treatment strategy, of administrating a second course of treatment, could lead to a high parasite clearance rate in patients treated with the combination regimen.

Pharmacological Validation of N-Myristoyltransferase as a Drug Target in Leishmania donovani

Visceral leishmaniasis (VL), caused by the protozoan parasites Leishmania donovani and L. infantum, is responsible for ∼30 000 deaths annually. Available treatments are inadequate, and there is a pressing need for new therapeutics. N-Myristoyltransferase (NMT) remains one of the few genetically validated drug targets in these parasites. Here, we sought to pharmacologically validate this enzyme in Leishmania. A focused set of 1600 pyrazolyl sulfonamide compounds was screened against L. major NMT in a robust high-throughput biochemical assay. Several potent inhibitors were identified with marginal selectivity over the human enzyme. There was little correlation between the enzyme potency of these inhibitors and their cellular activity against L. donovani axenic amastigotes, and this discrepancy could be due to poor cellular uptake due to the basicity of these compounds. Thus, a series of analogues were synthesized with less basic centers. Although most of these compounds continued to suffer from relatively poor antileishmanial activity, our most potent inhibitor of LmNMT (DDD100097, K i of 0.34 nM) showed modest activity against L. donovani intracellular amastigotes (EC50 of 2.4 μM) and maintained a modest therapeutic window over the human enzyme. Two unbiased approaches, namely, screening against our cosmid-based overexpression library and thermal proteome profiling (TPP), confirm that DDD100097 (compound 2) acts on-target within parasites. Oral dosing with compound 2 resulted in a 52% reduction in parasite burden in our mouse model of VL. Thus, NMT is now a pharmacologically validated target in Leishmania. The challenge in finding drug candidates remains to identify alternative strategies to address the drop-off in activity between enzyme inhibition and in vitro activity while maintaining sufficient selectivity over the human enzyme, both issues that continue to plague studies in this area.

An acute presentation of haemophagocytic lymphohistiocytosis due to visceral leishmaniasis in a British adult returning traveller

A 62-year old British Caucasian woman normally resident in Spain presented with fever and pancytopaenia after returning to the UK. Her symptoms persisted despite broad-spectrum antibiotics, and she gradually became confused, hypotensive and progressively more pancytopaenic. Imaging demonstrated hepatosplenomegaly, and a bone marrow aspirate confirmed a diagnosis of haemophagocytic lymphohistiocytosis (HLH). Bone marrow polymerase chain reaction (PCR) and blood serology were both positive for Leishmania donovani, consistent with visceral leishmaniasis (VL). Following treatment with dexamethasone and amphotericin, she improved clinically and biochemically, and was able to return to Spain. Fever in the returning traveller is a common acute medical presentation. Although HLH and VL are rare diagnoses, both carry a very high mortality rate if undiagnosed and untreated.

Miransertib (ARQ 092), an orally-available, selective Akt inhibitor is effective against Leishmania

Leishmaniasis is amongst the most important neglected diseases, afflicting more than 12 million people in 88 countries. There is an urgent need for safe orally bioavailable and cost-effective drugs for the treatment of leishmaniasis. It has recently been shown that Leishmania activates host macrophage serine/threonine kinase Akt, to promote survival of both parasites and infected cells. Here, we sought to evaluate a compound, Miransertib (ARQ 092), an orally bioavailable and selective allosteric Akt inhibitor currently in clinical trials for patients with PI3K/Akt-driven tumors or Proteus syndrome. Miransertib was tested against Leishmania donovani and Leishmania amazonensis, causative agents of visceral and cutaneous leishmaniasis, respectively. Cultured promastigotes were susceptible to Miransertib. In addition, Miransertib was markedly effective against intracellular amastigotes of L. donovani or L. amazonensis-infected macrophages. Miransertib also enhanced mTOR dependent autophagy in Leishmania-infected macrophages, which may represent one mechanism of Miransertib-mediated killing of intracellular Leishmania. Whereas parasite clearance in the spleen of mice infected with L. donovani and treated with Miransertib was comparable to that when treated with miltefosine, Miransertib caused a greater reduction in the parasite load in the liver. In the cutaneous leishmaniasis infection model, lesions were reduced by 40% as compared to mock treated mice. Together, these results provide direct evidence to support the conclusion that Miransertib is an excellent lead compound for the development of a new oral drug therapy for visceral and cutaneous leishmaniasis.

A rare case of visceral leishmaniasis in an immunocompetent traveler returning to the United States from Europe

A young, healthy traveler returning to the United States presented with fever, night sweats, splenomegaly, and pancytopenia. Bone marrow biopsy revealed leishmaniasis (Leishmania infantum), likely acquired in southern France. Although many cases of endemic visceral leishmaniasis (VL) have been reported in Europe, this is a rare case of imported VL in a healthy traveler returning from Europe to the US. Despite successful initial treatment with liposomal amphotericin B (LamB), relapse occurred. Treatments for VL in immunocompetent individuals are highly effective, but relapse can occur. There is more extensive experience in endemic areas with treating relapse that may be lacking in North America. This case alerts physicians in the US that immunocompetent adults can acquire VL during brief visits to endemic areas in Europe. It is important that travelers be counseled on preventive measures. Patients should be monitored after treatment for relapse.

Field safety and effectiveness of new visceral leishmaniasis treatment regimens within public health facilities in Bihar, India

BACKGROUND

In 2010, WHO recommended the use of new short-course treatment regimens in kala-azar elimination efforts for the Indian subcontinent. Although phase 3 studies have shown excellent results, there remains a lack of evidence on a wider treatment population and the safety and effectiveness of these regimens under field conditions.

METHODS

This was an open label, prospective, non-randomized, non-comparative, multi-centric trial conducted within public health facilities in two highly endemic districts and a specialist referral centre in Bihar, India. Three treatment regimens were tested: single dose AmBisome (SDA), concomitant miltefosine and paromomycin (Milt+PM), and concomitant AmBisome and miltefosine (AmB+Milt). Patients with complicated disease or significant co-morbidities were treated in the SDA arm. Sample sizes were set at a minimum of 300 per arm, taking into account inter-site variation and an estimated failure risk of 5% with 5% precision. Outcomes of drug effectiveness and safety were measured at 6 months. The trial was prospectively registered with the Clinical Trials Registry India: CTRI/2012/08/002891.

RESULTS

Out of 1,761 patients recruited, 50.6% (n = 891) received SDA, 20.3% (n = 358) AmB+Milt and 29.1% (n = 512) Milt+PM. In the ITT analysis, the final cure rates were SDA 91.4% (95% CI 89.3-93.1), AmB+Milt 88.8% (95% CI 85.1-91.9) and Milt+PM 96.9% (95% CI 95.0-98.2). In the complete case analysis, cure rates were SDA 95.5% (95% CI 93.9-96.8), AmB+Milt 95.5% (95% CI 92.7-97.5) and Milt+PM 99.6% (95% CI 98.6-99.9). All three regimens were safe, with 5 severe adverse events in the SDA arm, two of which were considered to be drug related.

CONCLUSION

All regimens showed acceptable outcomes and safety profiles in a range of patients under field conditions. Phase IV field-based studies, although extremely rare for neglected tropical diseases, are good practice and an important step in validating the results of more restrictive hospital-based studies before widespread implementation, and in this case contributed to national level policy change in India.

TRIAL REGISTRATION

Clinical trial is registered at Clinical trial registry of India (CTRI/2012/08/002891, Registered on 16/08/2012, Trial Registered Prospectively).

Estimating the efficacy of community-wide use of systemic insecticides in dogs to control zoonotic visceral leishmaniasis: A modelling study in a Brazilian scenario

Systemic insecticides in dogs have been suggested as a public health intervention to prevent human cases of Zoonotic Visceral Leishmaniasis (ZVL). But, currently there are no systemic insecticides for dogs registered against zoo-anthropophilic pool blood feeding phlebotomine flies. We predict the impact of community-wide use of systemic insecticide in dog populations as a public health measure to control transmission of Leishmania infantum to humans using a mathematical model. We developed a Susceptible-Exposed-Infected (SEI) compartmental model to describe L. infantum transmission dynamics in dogs, with a vectorial capacity term to represent transmission between L. infantum-hosting dogs via phlebotomine flies. For Infected (I) dogs two levels of infectiousness were modelled, high infectiousness and low infectiousness. Human incidence was estimated through its relationship to infection in the dog population. We evaluated outcomes from a wide range of scenarios comprising different combinations of initial insecticide efficacy, duration of insecticide efficacy over time, and proportion of the dog population treated (60%, 70% & 80%). The same reduction in human infection incidence can be achieved via different combinations of insecticide efficacy, duration and dog coverage. For example, a systemic insecticide with an initial efficacy of 80% and 6 months above 65% efficacy would require treating at least 70% of the dogs to reduce the human infection incidence by 50%. Sensitivity analysis showed that the model outcome was most sensitive to baseline values of phlebotomine fly daily survival rate and insecticide coverage. Community-wide use of systemic insecticides applied to the “L. infantum canine reservoir” can significantly reduce human incidence of L. infantum infection. The results of this mathematical model can help defining the insecticide target product profile and how the insecticide should be applied to maximise effectiveness.

Zoonotic visceral leishmaniasis (ZVL) is a potentially deadly disease in humans caused by Leishmania infantum. This leishmania species can be delivered by pool blood feeding zoo-anthropophilic phlebotomine flies to several mammals, the dog population being recognized as the main reservoir. Transmission from infected dogs to humans is through the bite of female phlebotomine sand flies. The disease is endemic in several countries and Brazil has a high prevalence of cases with over 3000 ZVL cases reported per year. The main, inefficient and highly controversial, control measure in Brazil has been culling sero-positive dogs. The community-wide use of systemic insecticides in dogs could be an alternative to control L. infantum transmission from phlebotomine flies to humans. The rationale is that phlebotomine flies which sampled their blood meals from dogs treated with systemic insecticides would die reducing the risk of L. infantum transmission. To reduce the number of ZVL cases, a large proportion of dogs in the community should be treated and the systemic insecticide used should be effective in killing phlebotomine flies acting as vectors of L. infantum parasites for a significant amount of time. We used a mathematical model mimicking L. infantum transmission to show that this novel vector control strategy could be effective. We identified the combination of different key parameters (e.g. insecticide efficacy, duration and proportion of dogs treated) that could lead to a significant reduction of the risk of L. infantum infection in humans.

Leishmaniasis

Leishmaniasis is a poverty-related disease with two main clinical forms: visceral leishmaniasis and cutaneous leishmaniasis. An estimated 0·7-1 million new cases of leishmaniasis per year are reported from nearly 100 endemic countries. The number of reported visceral leishmaniasis cases has decreased substantially in the past decade as a result of better access to diagnosis and treatment and more intense vector control within an elimination initiative in Asia, although natural cycles in transmission intensity might play a role. In east Africa however, the case numbers of this fatal disease continue to be sustained. Increased conflict in endemic areas of cutaneous leishmaniasis and forced displacement has resulted in a surge in these endemic areas as well as clinics across the world. WHO lists leishmaniasis as one of the neglected tropical diseases for which the development of new treatments is a priority. Major evidence gaps remain, and new tools are needed before leishmaniasis can be definitively controlled.

Knowledge, stigma, health seeking behaviour and its determinants among patients with post kalaazar dermal leishmaniasis, Bihar, India

Background

Lesishmaniasis is a neglected tropical disease endemic in Bihar, India. Inappropriate health seeking behaviour of post kala-azar dermal leishmaniasis (PKDL) patients may increase the disease duration, severity and transmissibility. Simultaneously, lack of knowledge and perceived stigma may also increase the length of delay in receiving treatment. This ultimately effects the kala-azar elimination program.

Methods

A cross sectional study was conducted in 120 confirmed PKDL patients, aged 18 years and older. Data related to knowledge and health seeking behaviour was collected by a pre-tested questionnaire. EMIC stigma scale was used for assessing the perceived stigma. Patients were personally interviewed after taking informed consent. Data analysis was done by using SPSS 16 software.

Results

The time between appearance of symptoms and first medical consultation (patient delay) ranged from 15 days to 5475 days (15 years) with a median of 285 days. The time between first medical consultations to onset of specific treatment (system delay) ranged from 2 to 5475 days with a median of 365 days. Many patients approached first to quacks (8.4%), homeopathic and ayurvedic practitioners (25.8%) upon recognition of symptoms. Majority of the patients (68.3%) had poor knowledge about PKDL and its vector. Type of skin lesions and gender had significant association with patient delay and system delay respectively (p<0.05). Distance to primary health centre (PHC) had significant association with patients delay as well as system delay (p<0.05). Patients with younger age, unmarried and polymorphic lesions had higher stigma (p<0.05). Patients with PKDL feel stigmatized in different areas.

Conclusion

PKDL treatment delays were unacceptably high and patients had poor knowledge compounded with feelings of stigmatization. To reduce the delay, a system may be evolved to establish some sort of public-private collaboration, besides awareness programs should be tailored, and implemented for improving the patient education regarding the disease and its linkage with VL.

Corneal complications following Post Kala-azar Dermal Leishmaniasis treatment

Post Kala-azar Dermal Leishmaniasis (PKDL) is a sequel of Visceral Leishmaniasis (VL). The patients act as a reservoir for the causative parasite (i.e. Leishmania donovani) and thus should be diagnosed and treated with the utmost urgency to prevent the transmission of the disease. In this study, we tried to report the first instances of corneal complications supposedly associated with Miltefosine (MF), in PKDL patients and the probable pathophysiology of such events. The recently rejuvenated National Kala-azar Elimination Program in Bangladesh has put great emphasis on monitoring all the leishmaniasis patients to investigate possible adverse drug reactions (ADR). A total of 194 patients have received Miltefosine for the treatment of Post Kala-azar Dermal Leishmaniasis. So far five patients were found to have developed unilateral ophthalmic complications during the periods from May 2016 to October 2017, after being treated with MF for PKDL. Unfortunately, one of whom had to go through complete evisceration of the affected eyeball. Despite the fact that MF is the only oral formulation of choice to treat PKDL, occurrences of such unexpected ADRs after MF administration urges the exploration of the pathogenesis of such incidents and determine measures to avert such occurrences from happening in future.

Concomitant T-cell prolymphocytic leukemia and visceral leishmaniasis: A case report

RATIONALE

T-cell prolymphocytic leukaemia (T-PLL) is a rare aggressive lymphoid disease featured by a significant increased lymphocyte count and obvious hepatosplenomegaly with poor prognosis. The concomitant presentation of T-PLL and visceral leishmaniasis (VL) has not previously been reported.

PATIENT CONCERNS

The patient initially suffered from anorexia, skin pigmentation, fever and hepatosplenomegaly. Bone marrow smear described leishmania and antibody test was positive. VL was diagnosed and he was given antimony gluconate therapy. His symptoms recurred.

DIAGNOSIS

A combination of serological rk39 test, morphologic evaluation and immunophenotyping by flow cytometry finally supported the diagnosis of concomitant VL and T-PLL.

OUTCOMES

Amphotericin B was used for the treatment of VL first and a referral for treating T-PLL after recovery from VL was suggested. Unfortunately, the patient requested to be discharged. Telephone follow-up indicated that he died a few days after leaving the hospital.

LESSONS

Due to the rarity of the disease combination, the pathogenesis association of T-PLL and VL is unclear. However, a duly diagnosis is crucial for treatment. In immunosuppressed patients due to malignancies and treatment, VL should be considered as an opportunistic infection. In VL infections, the clinical manifestations mimicking hematological malignancies may cover up the underlying disease. Under such conditions, a complete work-up based on laboratory test is necessary to achieve a correct diagnosis.

Visceral Leishmaniasis in Renal Transplant Recipients: Report of 2 Cases

Visceral leishmaniasis is a disease caused by the protozoan Leishmania and is transmitted by Lutzomyia longipalpis (sand fly). It is an endemic parasitic infection in numerous areas around the Mediterranean basin. Though immunocompetent patients may not develop the disease, in transplant recipients the use of corticoids and intensified immunosuppressants to prevent graft rejection may accelerate the disease, causing severe damage to the liver, spleen, and hematopoietic system. We report 2 cases of visceral leishmaniasis with an atypical presentation in transplant recipients. The first patient, who had a kidney transplant, was treated successfully with liposomal amphotericin B, and the second patient, a combined kidney-pancreas transplant recipient, suffered a relapse 3 years after treatment. Visceral leishmaniasis should be considered in the differential diagnosis of pancytopenia or unexplained fever occurring after organ transplantation in patients living in endemic areas or returning from endemic countries.

Visceral Leishmaniasis in Traveler to Guyana Caused by Leishmania siamensis, London, UK

The parasite Leishmania siamensis is a zoonotic agent of leishmaniasis; infection in animals has been documented in Europe and the United States. Reported authochthonous human infections have been limited to Thailand. We report a case of human visceral Leishmania siamensis infection acquired in Guyana, suggesting colonization in South America.

Biological evaluation and structure-activity relationships of imidazole-based compounds as antiprotozoal agents

We discovered a series of azole antifungal compounds as effective antiprotozoal agents. They displayed promising inhibitory activities within the micromolar-submicromolar range against P. falciparum, L. donovani, and T. b. rhodesiense. Moreover, most of such compounds showed excellent nanomolar IC₅₀ against T. cruzi, showing also very low cytotoxicity. Discussion of structure-activity relationships and biological data for these compounds are provided against the different parasites. To assess the mechanism of action against T. cruzi we proved that the most potent compounds (3b, 3j-l) inhibited the T. cruzi CYP51. Moreover, the most active derivative 3j dramatically reduced parasitemia in T. cruzi mouse model without acute toxicity.

Combined neutralization of interferon gamma and tumor necrosis factor alpha induces IL-4 production but has no direct additive impact on parasite burden in splenic cultures of human visceral leishmaniasis

Immune activating cytokines Interferon (IFN)-γ and Tumor necrosis factor (TNF)-α are known to activate macrophages for killing of Leishmania parasite. IFN-γ provides therapeutic potential while TNF-α has been recognized to mediate protection in visceral model of infection. In the present study we investigated whether combination of IFN-γ and TNF-α has better therapeutic strength than individually using one of these cytokines in Visceral Leishmaniasis (VL) patients. We performed combined blockade of IFN-γ and TNF-α in VL splenic biopsies and demonstrated it's impact on number of viable amastigotes and cytokine production. Additionally, selective depletion of splenic cell subsets was performed to establish the cellular sources of IFN-γ and TNF-α. Treatment of splenic aspirate cells with combination of anti-IFN-γ and anti-TNF-α monoclonal antibodies for 72 hours enabled no direct additive impact of these cytokines on parasite replication and IL-10 secretion, but IL-4 production was induced. Further assessment of splenic biopsies put forward CD4+ T cells as a source of IFN-γ whereas CD14+ cells contribute towards TNF-α production. Overall our results suggest, the interplay of pro-inflammatory cytokines IFN-γ derived from CD4+T lymphocytes and TNF-α from CD14+ cells has no direct additive impact on parasite replication but induces IL-4 production. Our data does not support direct targeting of IFN-γ and TNF-α for combination therapy but targeting these cytokines as an adjuvant in patients with exaggerated tissue inflammatory responses can have favourable patient outcome.

Design of commercially comparable nanotherapeutic agent against human disease-causing parasite, Leishmania

Nanotherapeutic agents (NTA) play a crucial role in clinical medicine, if their unique properties are well understood and well exploited. In this direction, we report synthesis and characterization of highly potent phytofabricated silver nanoparticles (AgNPs) using Sechium edule, which served the purpose of both reducing and capping agent. The designed AgNPs were characterized using UV-Vis spectroscopy, XRD, FTIR, HR-TEM, and TGA techniques. The formation of AgNPs was also confirmed using electrochemistry, which to the best of our knowledge has never been reported before for biosynthesized nanoparticles. The antileishmanial potential of AgNPs was examined on the clinical isolates of Leishmania donovani promastigote cells in an in vitro experimental setting. A dose dependent killing activity of the AgNP was observed with an IC50 value of 51.88 ± 3.51 µg/ml. These results were also compared using commercially available drug, miltefosine. Furthermore, the clinical applicability of AgNP, as antileishmanial agent was proven by testing them against normal mammalian monocyte cell line (U937). The results were statistically analyzed and no significant toxicity of AgNPs on the normal mammalian cells was observed.

A conserved Leishmania hypothetical protein evaluated for the serodiagnosis of canine and human visceral and tegumentary leishmaniasis, as well as a serological marker for the posttreatment patient follow-up

In the present study, a conserved Leishmania hypothetical protein, LiHyE, was evaluated for the serodiagnosis of leishmaniasis. Results showed that it presented high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to serologically identify visceral leishmaniasis (VL) dogs when 40 positive sera and 95 cross-reactive samples were used. rLiHyE also showed the best results of sensitivity, specificity, PPV, and NPV to identify tegumentary leishmaniasis (TL) and VL patients when 45 leishmaniasis patients' sera and 90 cross-reactive samples were used. Results were better in comparison to those obtained when rA2 or Leishmania antigenic extract was employed as controls. The posttreatment follow-up showed that rLiHyE-specific antibodies declined significantly after the end of treatments, and a predominance of the IgG2 subclass was found in comparison to IgG1 levels in both TL and VL patients. In conclusion, rLiHyE can be considered a candidate for the serodiagnosis of canine and human leishmaniasis.

The initial effectiveness of liposomal amphotericin B (AmBisome) and miltefosine combination for treatment of visceral leishmaniasis in HIV co-infected patients in Ethiopia: A retrospective cohort study

BACKGROUND

North-west Ethiopia faces the highest burden world-wide of visceral leishmaniasis (VL) and HIV co-infection. VL-HIV co-infected patients have higher (initial) parasitological failure and relapse rates than HIV-negative VL patients. Whereas secondary prophylaxis reduces the relapse rate, parasitological failure rates remain high with the available antileishmanial drugs, especially when administered as monotherapy. We aimed to determine the initial effectiveness (parasitologically-confirmed cure) of a combination of liposomal amphotericin B (AmBisome) and miltefosine for treatment of VL in HIV co-infected patients.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a retrospective cohort study at a Médecins Sans Frontières-supported health center in north-west Ethiopia. We included VL-HIV co-infected adults, treated for VL between January 2011 and August 2014, with AmBisome infusion (30 mg/kg total dose) and miltefosine orally for 28 days (100 mg/day). Proportions of initial treatment outcome categories were calculated. Predictors of initial parasitological failure and of death were determined using multivariable logistic regression. Of the 173 patients included, 170 (98.3%) were male and the median age was 32 years. The proportion of patients with primary VL (48.0%) and relapse VL (52.0%) were similar. The majority had advanced HIV disease (n = 111; 73.5%) and were on antiretroviral therapy prior to VL diagnosis (n = 106; 64.2%). Initial cure rate was 83.8% (95% confidence interval [CI], 77.6-88.6); death rate 12.7% (95% CI, 8.5-18.5) and parasitological failure rate 3.5% (95% CI, 1.6-7.4). Tuberculosis co-infection at VL diagnosis was predictive of parasitological failure (adjusted odds ratio (aOR), 8.14; p = 0.02). Predictors of death were age >40 years (aOR, 5.10; p = 0.009), hemoglobin ≤6.5 g/dL (aOR, 5.20; p = 0.002) and primary VL (aOR, 8.33; p = 0.001).

CONCLUSIONS/SIGNIFICANCE

Initial parasitological failure rates were very low with AmBisome and miltefosine combination therapy. This regimen seems a suitable treatment option. Knowledge of predictors of poor outcome may facilitate better management. These findings remain to be confirmed in clinical trials.

Complex Interplay between Sphingolipid and Sterol Metabolism Revealed by Perturbations to the Leishmania Metabolome Caused by Miltefosine

With the World Health Organization reporting over 30,000 deaths and 200,000 to 400,000 new cases annually, visceral leishmaniasis is a serious disease affecting some of the world's poorest people. As drug resistance continues to rise, there is a huge unmet need to improve treatment. Miltefosine remains one of the main treatments for leishmaniasis, yet its mode of action (MoA) is still unknown. Understanding the MoA of this drug and parasite response to treatment could help pave the way for new and more successful treatments for leishmaniasis. A novel method has been devised to study the metabolome and lipidome of Leishmania donovani axenic amastigotes treated with miltefosine. Miltefosine caused a dramatic decrease in many membrane phospholipids (PLs), in addition to amino acid pools, while sphingolipids (SLs) and sterols increased. Leishmania major promastigotes devoid of SL biosynthesis through loss of the serine palmitoyl transferase gene (ΔLCB2) were 3-fold less sensitive to miltefosine than wild-type (WT) parasites. Changes in the metabolome and lipidome of miltefosine-treated L. major mirrored those of L. donovani A lack of SLs in the ΔLCB2 mutant was matched by substantial alterations in sterol content. Together, these data indicate that SLs and ergosterol are important for miltefosine sensitivity and, perhaps, MoA.

Phlebotomine mortality effect of systemic insecticides administered to dogs

BACKGROUND

Zoonotic visceral leishmaniasis (ZVL) caused by Leishmania (Leishmania) infantum is an important disease in humans and dogs. Different mammal species are reservoirs but dogs are considered to be the main one. Phlebotomine sand flies are the proven vector. Four systemic insecticides approved for their use in dogs were previously selected based on their potential to be used in endemic countries as part of the control programs of ZVL. These insecticides are proved to be safe and effective against the on-label insects and parasites, but there is no information about their activity against phlebotomine sand flies.

METHODS

The phlebotomine mortality of four systemic insecticides in dogs was evaluated using two randomized clinical trials. For the first trial, thirty dogs were randomly allocated into five groups: four treatments and one control, of equal size. The treatments evaluated were: Guardian®SR, Elanco (moxidectin); Comfortis®, Elanco (spinosad); Bravecto®, Merck Animal Health (fluralaner); and NexGard®, Merial (afoxolaner). Blood from dogs was taken at days 2, 4, 21 and 31 post-treatment (trial 1). The compound that showed the highest efficacy was selected for a second trial (trial 2) with 20 dogs sampled at days 0, 2, 4, 7, 14, 18, 32, 39, 51 and 84 post-treatment. Membrane feeding bioassays with Phlebotomus papatasi were used to evaluate the phlebotomine mortality efficacy of the different treatments. Phlebotomine mortality was observed every 24 h following the membrane feeding during 5 days. A mixed model for a negative binomial logistic regression, and a Cox proportional hazard mixed model were used to estimate phlebotomine mortality due to different treatments.

RESULTS

Fluralaner was the only compound that showed significant phlebotomine mortality. Fluralaner maintained the phlebotomine mortality between 60-80% for 30 days after treatment. In trial 1 we found that fluralaner increased the risk of death by 1.9 times (95% CI: 1.02-3.6) and 1.7 times (95% CI: 1.09-2.6) at days 2 and 4 after treatment. The Cox model resulted in an increase of 1.47 (95% CI: 1.1-1.96) times in hazard risk at day 2 and 1.89 (95% CI: 1.35-2.45) at day 4 after treatment. In trial 2 we found that fluralaner increased the risk of death by 1.64 times (95% CI: 1.16-2.54) and 1.97 times (95% CI: 1.23-3.17) at days 14 and 32. The hazard risk was also increased by 1.92 (95% CI: 1.4-2.64) times at day 14 after treatment. Phlebotomine survival including all experimental days was significantly lower in the fluralaner group in both trials.

CONCLUSIONS

A single oral treatment of fluralaner in dogs induces phlebotomine mortality. Systemic insecticides in dogs should be considered as a potential preventive measure of ZVL.