Aminosidine and its combination with sodium stibogluconate in the treatment of diffuse cutaneous leishmaniasis caused by Leishmania aethiopica

Treatment outcomes of cutaneous leishmaniasis due to Leishmania aethiopica: A systematic review and meta-analysis

BACKGROUND

Leishmania aethiopica is a unique species that causes cutaneous leishmaniasis (CL), and studies evaluating treatment outcomes for this condition reported inconsistent findings. This study aimed to summarize the evidence on treatment outcomes of CL caused by L. aethiopica to support decisions or propose further study.

METHODS

We searched PubMed, Scopus, and ScienceDirect. In addition, we searched grey literature on Google Scholar and performed manual searching on the reference list of articles. Two authors did the screening, selection, critical appraisal, and data extraction. With the narrative synthesis of evidence, we performed a random effects model meta-analysis using the metaprop package in Stata 17. We did sensitivity and subgroup analyses after assessing heterogeneity using the I-squared test and forest plots. The funnel plot and Egger's test were used to assess publication bias.

RESULTS

The review included 22 studies with 808 participants, and the meta-analysis included seven studies with 677 participants. Most studies documented treatment outcomes with antimonial monotherapy, and only one study reported outcomes with combination therapy. The overall pooled proportion of cure was 63% (95% CI: 38-86%). In the subgroup analysis, systemic antimonial monotherapy showed a cure rate of 61%, and the proportion of cure was 87% with topical therapy. Topical therapy showed a better cure for the localized clinical phenotype. A cohort study documented a cure rate of 94.8% with combination therapy for the localized, mucocutaneous, and diffuse clinical phenotypes. The pooled proportion of unfavourable outcomes was partial response (19%), relapse (17%), discontinuation (19%), and unresponsiveness (6%).

CONCLUSIONS

The pooled proportion of cure is low with antimonial monotherapy. Despite limited evidence, combination therapies are a promising treatment option for all clinical phenotypes of CL caused by L. aethiopica. Future high-quality randomized control trials are needed to identify effective monotherapies and evaluate the effectiveness of combination therapies.

In vitro growth inhibitory activity of Medicines for Malaria Venture pathogen box compounds against Leishmania aethiopica

Introduction

Leishmania aethiopica (L. aethiopica) is responsible for different forms of cutaneous leishmaniasis (CL) in Ethiopia. Treatment heavily depends on limited drugs, together with drawbacks like toxicity and microbial resistance. The current research aimed to investigate in vitro growth inhibitory activity of Medicines for Malaria Ventures - Pathogen Box (MMV - PB) compounds against L. aethiopica clinical isolate.

Methodology

Four hundred MMV – PB compounds were screened against L. aethiopica using resazurin based colourimetric assay. Compounds with > 70% inhibition were further tested using macrophage based intracellular amastigote assay. Cytotoxic and hemolytic activity of candidate hits were assessed on THP1- cells and sheep red blood cells (RBCs), respectively. In vitro drug interaction study was also conducted for the most potent hit using the combination index method.

Results

At the test concentration of 1 μM, twenty-three compounds showed > 50% inhibition of promastigotes parasite growth, of which 11 compounds showed > 70% inhibition. The 50% growth inhibition (IC₅₀) of the 11 compounds was ranged from 0.024 to 0.483 μM in anti-promastigote assay and from 0.064 to 0.899 μM in intracellular amastigote assay. Candidate compounds demonstrated good safety on sheep RBCs and THP-1 cell lines. MMV688415 demonstrated a slight hemolytic activity on sheep RBC (5.3% at 25 μM) and THP-1 cell line (CC₂₀ = 25 μM) while MMV690102 inhibited half of THP-1 cells at 36.5 μM (selectivity index = 478). No synergistic activity was observed from the combinations of MMV690102 and amphotericin B (CI > 1), and MMV690102 and Pentamidine (CI > 1) at lower and higher combination points.

Conclusion

The present study identified a panel of compounds that can be used as a novel starting point for lead optimization. MMV690102 appears to be the most potent inhibitor against L. aethiopica promastigotes and amastigotes. Future works should investigate the antileishmanial mechanism of action and in vivo antileishmanial activities of identified hits.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00538-2.

Susceptibility to paromomycin in clinical isolates and reference strains of Leishmania species responsible for tegumentary leishmaniasis in Brazil

Treatment of tegumentary leishmaniasis in Brazil is limited to pentavalent antimonial, amphotericin B and pentamidine. These drugs, administered parenterally, cause several side effects and have a varied clinical response, depending on the species of Leishmania. Urgent expansion of the therapeutic arsenal against the disease is therefore necessary. Paromomycin is an aminoglycoside antibiotic that has already been approved for the treatment of visceral leishmaniasis in Southeast Asia. Here, we provide an in vitro evaluation of the activity of paromomycin in fifteen clinical isolates from patients with tegumentary leishmaniasis at a reference center for the treatment of the disease. Furthermore, the in vitro susceptibility to this drug in reference strains of Leishmania species that are endemic in Brazil has also been evaluated. Among the clinical isolates, nine were typed as Leishmania (Viannia) braziliensis, five as L. (Leishmania) amazonensis and one as L. (V.) guyanensis. Although never exposed to paromomycin, we found variable susceptibility among these isolates and reference strains in promastigotes and intracellular amastigotes, with the drug being more active in the amastigote form of the parasite. This study provides a preclinical dataset that is useful for the evaluation of paromomycin in the treatment of tegumentary leishmaniasis caused by species that are endemic in Brazil.

Activity of paromomycin against Leishmania amazonensis: Direct correlation between susceptibility in vitro and the treatment outcome in vivo

Paromomycin is an aminoglycoside antibiotic approved in 2006 for the treatment of visceral leishmaniasis caused by Leishmania donovani in Southeast Asia. Although this drug is not approved for the treatment of visceral and cutaneous leishmaniasis in Brazil, it is urgent and necessary to evaluate the potential of this drug as alternative for the treatment against species responsible for these clinical forms of the disease. In Brazil, Leishmania amazonensis is responsible for cutaneous and diffuse cutaneous leishmaniasis. The diffuse cutaneous form of the disease is difficult to treat and frequent relapses are reported, mainly when the treatment is interrupted. Here, we evaluated paromomycin susceptibility in vitro of a L. amazonensis clinical isolate from a patient with cutaneous leishmaniasis and the reference strain L. amazonensis M2269, as well as its in vivo efficacy in a murine experimental model. Although never exposed to paromomycin, a significant differential susceptibility between these two lines was found. Paromomycin was highly active in vitro against the clinical isolate in both forms of the parasite, while its activity against the reference strain was less active. In vivo studies in mice infected with each one of these lines demonstrated that paromomycin reduces lesion size and parasite burden and a direct correlation between the susceptibility in vitro and the effectiveness of this drug in vivo was found. Our findings indicate that paromomycin efficacy in vivo is dependent on intrinsic susceptibility of the parasite. Beyond that, this study contributes for the evaluation of the potential use of paromomycin in chemotherapy of cutaneous leishmaniasis in Brazil caused by L. amazonensis.

The Novel Serine/Threonine Protein Kinase LmjF.22.0810 from Leishmania major may be Involved in the Resistance to Drugs such as Paromomycin

The identification and clarification of the mechanisms of action of drugs used against leishmaniasis may improve their administration regimens and prevent the development of resistant strains. Herein, for the first time, we describe the structure of the putatively essential Ser/Thr kinase LmjF.22.0810 from Leishmania major. Molecular dynamics simulations were performed to assess the stability of the kinase model. The analysis of its sequence and structure revealed two druggable sites on the protein. Furthermore, in silico docking of small molecules showed that aminoglycosides preferentially bind to the phosphorylation site of the protein. Given that transgenic LmjF.22.0810-overexpressing parasites displayed less sensitivity to aminoglycosides such as paromomycin, our predicted models support the idea that the mechanism of drug resistance observed in those transgenic parasites is the tight binding of such compounds to LmjF.22.0810 associated with its overexpression. These results may be helpful to understand the complex machinery of drug response in Leishmania.

Cutaneous Leishmaniasis Due to Leishmania aethiopica

Leishmania aethiopica is the main causative species for cutaneous leishmaniasis (CL) in Ethiopia. Despite its considerable burden, L. aethiopica has been one of the most neglected Leishmania species. In this review, published evidence on L. aethiopica history, geography, vector, reservoir, epidemiology, parasitology, and immunology is discussed and knowledge gaps are outlined. L. aethiopica endemic regions are limited to the highland areas, although nationwide studies on CL prevalence are lacking. Phlebotomus pedifer and P. longipes are the sandfly vectors and hyraxes are considered to be the main reservoir, but the role of other sandfly species and other potential reservoirs requires further investigation. Where and how transmission occurs exactly are also still unknown. Most CL patients in Ethiopia are children and young adults. Lesions are most commonly on the face, in contrast to CL caused by other Leishmania species which may more frequently affect other body parts. CL lesions caused by L. aethiopica seem atypical and more severe in their presentation as compared to other Leishmania species. Mucocutaneous leishmaniasis and diffuse cutaneous leishmaniasis are relatively common, and healing of lesions caused by L. aethiopica seems to take longer than that of other species. A thorough documentation of the natural evolution of L. aethiopica as well as in depth studies into the immunological and parasitological characteristics that underpin the atypical and severe clinical presentation are needed. Better understanding of CL caused by this parasite species will contribute to interventions related to transmission, prevention, and treatment.

Treatment of Cutaneous Leishmaniasis Caused by Leishmania aethiopica: A Systematic Review

Leishmania aethiopica is the etiological agent of cutaneous leishmaniasis (CL) in Ethiopia and can cause severe and complicated cases such as diffuse CL (DCL), mucocutaneous leishmaniasis or extensive CL, requiring systemic treatment. Despite the substantial burden, evidence-based treatment guidelines are lacking. We conducted a systematic review of clinical studies reporting on treatment outcomes of CL due to L aethiopica in order to help identify potentially efficacious medications on CL that can be taken forward for clinical trials. We identified a total of 24 records reporting on 506 treatment episodes of CL presumably due to L aethiopica. The most commonly used drugs were antimonials (n = 201), pentamidine (n = 150) and cryotherapy (n = 103). There were 20 case reports/series, with an overall poor study quality. We only identified two small and/or poor quality randomized controlled trials conducted a long time ago. There were two prospective non-randomized studies reporting on cryotherapy, antimonials and pentamidine. With cryotherapy, cure rates were 60-80%, and 69-85% with antimonials. Pentamidine appeared effective against complicated CL, also in cases non-responsive to antimonials. However, all studies suffered from methodological limitations. Data on miltefosine, paromomycin and liposomal amphotericin B are extremely scarce. Only a few studies are available on DCL. The only potentially effective treatment options for DCL seem to be antimonials with paromomycin in combination or pentamidine, but none have been properly evaluated. In conclusion, the evidence-base for treatment of complicated CL due to L aethiopica is extremely limited. While antimonials remain the most available CL treatment in Ethiopia, their efficacy and safety in CL should be better defined. Most importantly, alternative first line treatments (such as miltefosine or paromomycin) should be explored. High quality trials on CL due to L aethiopica are urgently needed, exploring group sequential methods to evaluate several options in parallel.

Miltefosine: a review of its pharmacology and therapeutic efficacy in the treatment of leishmaniasis

Miltefosine is an alkylphosphocholine drug with demonstrated activity against various parasite species and cancer cells as well as some pathogenic bacteria and fungi. For 10 years it has been licensed in India for the treatment of visceral leishmaniasis (VL), a fatal neglected parasitic disease. It is the first and still the only oral drug that can be used to treat VL and cutaneous leishmaniasis (CL). The standard 28 day miltefosine monotherapy regimen is well tolerated, except for mild gastrointestinal side effects, although its teratogenic potential severely hampers its general use in the clinic and roll-out in national elimination programmes. The pharmacokinetics of miltefosine are mainly characterized by its long residence time in the body, resulting in extensive drug accumulation during treatment and long elimination half-lives. At the moment, different combination therapy strategies encompassing miltefosine are being tested in multiple controlled clinical trials in various geographical areas of endemicity, both in South Asia and East Africa. We here review the most salient pre-clinical and clinical pharmacological aspects of miltefosine, its mechanism of action against Leishmania parasites and other pathogens, and provide a systematic overview of the efficacy and safety data from all clinical trials of miltefosine, either alone or in combination, in the treatment of VL and CL.

Drug resistance in leishmaniasis

The treatment options of leishmaniasis are limited and far from satisfactory. For more than 60 years, treatment of leishmaniasis has centered around pentavalent antimonials (Sb^v). Widespread misuse has led to the emergence of Sb^v resistance in the hyperendemic areas of North Bihar. Other antileishmanials could also face the same fate, especially in the anthroponotic cycle. The HIV/ visceral leishmaniasis (VL) coinfected patients are another potential source for the emergence of drug resistance. At present no molecular markers of resistance are available and the only reliable method for monitoring resistance of isolates is the technically demanding in vitro amastigote-macrophage model. As the armametrium of drugs for leishmaniasis is limited, it is important that effective monitoring of drug use and response should be done to prevent the spread of resistance. Regimens of simultaneous or sequential combinations should be seriously considered to limit the emergence of resistance.

Case report: Successful treatment of cutaneous leishmaniasis caused by Leishmania aethiopica with liposomal amphothericin B in an immunocompromised traveler returning from Eritrea

Cutaneous leishmaniasis caused by Leishmania aethiopica is rarely encountered outside disease-endemic areas and there have been no clinical trials evaluating its pharmacotherapy. We describe the treatment of cutaneous leishmaniasis caused by L. aethiopica using liposomal amphothericin B in an immunocompromised traveler returning from Eritrea.

Therapeutic switching in leishmania chemotherapy: a distinct approach towards unsatisfied treatment needs

Current drugs for the treatment of visceral leishmaniasis are inadequate. No novel compound is in the pipeline. Since economic returns on developing a new drug for neglected disease, leishmaniasis is so low that therapeutic switching represents the only realistic strategy. It refers to "alternative drug use" discoveries which differ from the original intent of the drug. Amphotericin B, paromomycin, miltefosine and many other drugs are very successful examples of "new drugs from old". This article reviews the discovery, growth and current status of these drugs and concluded that the potential of this approach (therapeutic switching) may use in the development of new antileishmanials in future also.

Paromomycin

Paromomycin is an aminoglycoside that is active against Gram-negative and many Gram-positive bacteria as well as some protozoa and cestodes. It is out of use as an antibiotic but was licensed in 2007 in India as an effective, well tolerated and affordable treatment for visceral leishmaniasis (VL) at a dose of 11 mg/kg (base) for 21 days. Currently, the non-profit group Drugs for Neglected Diseases Initiative is conducting studies on paromomycin (as monotherapy and in combination) in VL in Africa, and the Institute for OneWorld Health is conducting a Phase IV study in India. Paromomycin in combination with sodium stibogluconate has proven to be effective in African and Indian VL and improves survival in African VL. To prevent the emergence of drug-resistant leishmaniasis in areas of anthroponotic transmission (India and Africa), paromomycin should be used as part of combination therapy for VL. Further trials testing different combinations are much needed. In addition, the distribution of paromomycin (like other drugs for leishmaniasis) should be well regulated and preferably restricted to the public sector. These strategies should ensure the longevity of paromomycin as a useful drug for VL.

Interventions for Old World cutaneous leishmaniasis

BACKGROUND

Cutaneous leishmaniasis is caused by a parasitic infection and is considered one of the most serious skin diseases in many developing countries. Antimonials are the most commonly prescribed treatment but other drugs have been used with varying success.

OBJECTIVES

To assess the effects of treatments for Old World cutaneous leishmaniasis (OWCL).

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (April 2008), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2008), MEDLINE (2003-April 2008), EMBASE (2005-April 2008), CINAHL (1982-August 2007), LILACS (from inception to April 2008) and ongoing trials databases (August 2007).

SELECTION CRITERIA

Randomised controlled trials assessing treatments in immuno-competent people with OWCL confirmed by smear, histology, culture or polymerase chain reaction.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We included 49 trials involving 5559 participants. Reporting quality was generally poor and only two studies contained sufficiently similar data to pool.In Leishmania major infections, there was good RCT evidence of benefit of cure around 3 months after treatment when compared to placebo for 200 mg oral fluconazole (1 RCT n = 200, RR 2.78; 95% CI 1.86, 4.16), topical 15% paromomycin + 12% methylbenzethonium chloride (PR-MBCL) (1 RCT n = 60, RR 3.09; 95% CI 1.14, 8.37) and photodynamic therapy (1 RCT n = 60, RR 7.02; 95% CI 3.80, 17.55). Topical PR-MBCL was less efficacious than photodynamic therapy (1 RCT n = 65, RR 0.44; 95% CI 0.29, 0.66). Oral pentoxifylline was a good adjuvant therapy to intramuscular meglumine antimoniate (IMMA) when compared to IMMA plus placebo (1 RCT n = 64, RR 1.63; 95% CI 1.11, 2.39)In Leishmania tropica infections, there was good evidence of benefit for the use of 200 mg oral itraconazole for 6 weeks compared with placebo (1 RCT n = 20, RR 7.00; 95% CI 1.04, 46.95), for intralesional sodium stibogluconate (1 RCT n = 292, RR 2.62; 95% CI 1.78, 3.86), and for thermotherapy compared with intramuscular sodium stibogluconate (1 RCT n = 283, RR 2.99; 95% CI 2.04, 4.37).

AUTHORS' CONCLUSIONS

Most trials have been designed and reported poorly, resulting in a lack of evidence for potentially beneficial treatments. There is a desperate need for large well conducted studies that evaluate long-term effects of current therapies. We suggest the creation of an international platform to improve quality and standardization of future trials in order to inform clinical practice.

Combined effect of the essential oil from Chenopodium ambrosioides and antileishmanial drugs on promastigotes of Leishmania amazonensis

To date, there are no vaccines against Leishmania, and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs of choice used for leishmaniasis therapy are significantly toxic, expensive and with a growing frequency of refractory infections. Because of these limitations, a combination therapy is the better hope. This work demonstrates that the essential oil from Chenopodium ambrosioides shows a synergic activity after incubation in conjunction with pentamidine against promastigotes of Leishmania amazonensis. However, an indifferent effect has been found for combinations of meglumine antimoniate or amphotericin B and the essential oil.

Leishmania (Kinetoplastida): Species typing with isoenzyme and PCR–RFLP from cutaneous leishmaniasis patients in Ethiopia

Cutaneous leishmaniasis (CL) is an increasing public health problem in Ethiopia. There is a concern that it is spreading with increased incidence. In this study, we used isoenzyme electrophoresis and internal transcribed spacer one (ITS1) PCR-RFLP techniques to identify Leishmania species from CL patients in Ethiopia. We obtained isolates from 55 localized cutaneous leishmaniasis (LCL), 3 diffused cutaneous leishmaniasis (DCL) and 36 biopsy samples from 34 LCL and 2 DCL cases from All Africa Leprosy and Tuberculosis Rehabilitation and Training Center (ALERT) and clinically diagnosed CL cases from Ochollo village. Both isoenzyme and ITS1 PCR-RFLP techniques showed that Leishmania aethiopica (L. aethiopica) was the aetiologic agent in all cases. Our study also showed that ITS1 PCR-RFLP could identify Leishmania species from biopsy samples and suggests the method could be used for epidemiological surveillance of leishmaniasis in Ethiopia and for species-specific diagnosis.

Cutaneous leishmaniasis

Cutaneous leishmaniasis is a widespread tropical infection caused by numerous different species of Leishmania protozoa that are transmitted by sandflies. Its clinical presentations are extremely diverse and dependent on a variety of parasite and host factors that are poorly understood. Diagnosis should aim to identify the exact species involved, but this requires laboratory investigations that are not widely available. No single ideal treatment has been identified, and those available are limited by variable success rates and toxicity. Clinical guidelines are needed to make better use of the investigations and treatments that do exist. Prevention is currently limited to bite prevention measures.

Chemotherapy in the treatment and control of leishmaniasis

Drugs remain the most important tool for the treatment and control of both visceral and cutaneous leishmaniasis. Although there have been several advances in the past decade, with the introduction of new therapies by liposomal amphotericin, oral miltefosine and paromomycin (PM), these are not ideal drugs, and improved shorter duration, less toxic and cheaper therapies are required. Treatments for complex forms of leishmaniasis and HIV co-infections are inadequate. In addition, full deployment of drugs in treatment and control requires defined strategies, which can also prevent or delay the development of drug resistance.

Treatment options for visceral leishmaniasis

This review summarizes the current developments in therapy for visceral leishmaniasis. With the recent introduction of new drugs, the main limits in reducing deaths from visceral leishmaniasis are difficulty in diagnosis in the field and health inequality--patients lack of access to treatment. No new drugs are currently in the early stages of development. There are good reasons for the use of combination therapy; to prevent further development of resistance against the limited therapeutic options available.

Drug resistance in leishmaniasis

Leishmaniasis is a complex disease, with visceral and cutaneous manifestations, and is caused by over 15 different species of the protozoan parasite genus Leishmania. There are significant differences in the sensitivity of these species both to the standard drugs, for example, pentavalent antimonials and miltefosine, and those on clinical trial, for example, paromomycin. Over 60% of patients with visceral leishmaniasis in Bihar State, India, do not respond to treatment with pentavalent antimonials. This is now considered to be due to acquired resistance. Although this class of drugs has been used for over 60 years for leishmaniasis treatment, it is only in the past 2 years that the mechanisms of action and resistance have been identified, related to drug metabolism, thiol metabolism, and drug efflux. With the introduction of new therapies, including miltefosine in 2002 and paromomycin in 2005-2006, it is essential that there be a strategy to prevent the emergence of resistance to new drugs; combination therapy, monitoring of therapy, and improved diagnostics could play an essential role in this strategy.

Miltefosine (Impavido): the first oral treatment against leishmaniasis

Miltefosine is a novel antileishmanial drug that has significant selectivity in both in vitro and in vivo models. Clinical efficacy was demonstrated for the treatment of visceral leishmaniasis with the advantage of oral administration over the currently recommended antileishmanial drugs that require parenteral administration. Miltefosine produces high cure rates also in patients resistant to the standard antimonial therapy.

Monitoring drug resistance in leishmaniasis

There are many factors that can influence the efficacy of drugs in the treatment of leishmaniasis. These include both an intrinsic variation in the sensitivity of Leishmania species, described for pentavalent antimonials, paromomycin, azoles and other drugs that have reached clinical trials, as well as acquired drug resistance to antimonials. Acquired resistance has been studied in the laboratory for several decades but it is only recently that clinical resistance in L. donovani field isolates has been demonstrated. The monitoring of resistance is problematic due to a reliance on the amastigote-macrophage culture assay to adequately correlate clinical and in vitro resistance and a lack of knowledge about the molecular and biochemical mechanisms of resistance to antileishmanial drugs.

Genetic variability within the species Leishmania aethiopica does not correlate with clinical variations of cutaneous leishmaniasis

Leishmania aethiopica infections in man result in a spectrum of diseases from LCL to DCL. These clinical manifestations have been attributed to genetic differences within the host or the parasites. In this study two different PCR-based methods were used to elucidate genetic variation within the species L. aethiopica. Inter- and intra-specific variations were detected in the ITS of the ribosomal operon in different strains and species of Leishmania, using a PCR-RFLP approach, and by a PCR fingerprinting technique that used single non-specific primers to amplify polymorphic regions of the genomic DNA. Both methods revealed genetic heterogeneity among ten L. aethiopica isolates examined. Unrooted distance trees separated the ten strains into two different genetic groups. This subdivision was correlated to the geographical origin of the isolates rather than to the clinical manifestation of the disease.

Treatment of two patients with diffuse cutaneous leishmaniasis caused by Leishmania mexicana modifies the immunohistological profile but not the disease outcome

Two patients with diffuse cutaneous leishmaniasis caused by Leishmania mexicana were treated with two leishmanicidal drugs (pentamidine and allopurinol) combined with recombinant interferon-gamma restoring Th-1 favouring conditions in the patients. Parasites decreased dramatically in the lesions and macrophages diminished concomitantly, while IL-12-producing Langerhans cells and interferon-gamma- producing NK and CD8 + lymphocytes increased in a reciprocal manner. The CD4+/CD8 + ratio in the peripheral blood normalized. During exogenous administration of interferon-gamma the parasites' capacity to inhibit the oxidative burst of the patients' monocytes was abolished. Even though Th-1-favouring conditions were restored, both patients relapsed two months after therapy was discontinued. We conclude that the tendency to develop a disease-promoting Th-2 response in DCL patients is unaffected by, and independent of, parasite numbers. Even though intensive treatment in DCL patients induced Th-1 disease restricting conditions, the disease-promoting immunomodulation of few persistent Leishmania sufficed to revert the immune response.

New developments in the chemotherapy of leishmaniasis

Several significant advances in the chemotherapy of leishmaniasis have occurred in the last 10 years. Some of these advances have arisen due to the greater awareness of the pharmacokinetic properties of drugs, such as the pentavalent antimonials, while others have resulted from the introduction of drugs new to the treatment of leishmaniasis, such as aminosidine which can be used both systemically and topically against cutaneous leishmaniasis. The most encouraging advance is the use of lipid-associated amphotericin B; very short treatments with these preparations have been shown to be effective. Other studies have shown the usefulness of combination therapy and the use of immune modulators. A number of biochemical pathways in Leishmania, such as those associated with purine and sterol metabolism, are known to be distinct from those of the mammalian hosts. These have been exploited in the search for the rational choice of anti-leishmanial agents.

Aminosidine plus sodium stibogluconate for the treatment of Indian kala-azar: a randomized dose-finding clinical trial

This randomized, open sequential design trial was set up to assess the efficacy, tolerability and toxicity of 20 d courses of combined intramuscular aminosidine and sodium stibogluconate at various dosages in patients with newly-diagnosed kala-azar in Bihar, India. Three successive studies of 96 patients each were originally planned with aminosidine administered at 12, 6 and 3 mg/kg/d, respectively. For each aminosidine dosage, patients were randomly assigned to receive sodium stibogluconate at 20, 10 or 5 mg/kg/d of antimony. Ninety-six patients were enrolled and assigned aminosidine 12 mg/kg/d as scheduled. In the subsequent study with aminosidine at 6 mg/kg/d, the trial was interrupted after 40 patients had entered owing to inadequacy of the treatment. With aminosidine 12 mg/kg/d the success rates with sodium stibogluconate at 20, 10 and 5 mg/kg/d were 88%, 71% and 72%, respectively and did not differ significantly. With aminosidine 6 mg/kg/d, 69%, 50% and 46% of patients were cured with the same sodium stibogluconate doses, respectively; again, there was no significant difference between the subgroups. The overall success rate with aminosidine at 12 mg/kg/d (76%) was significantly higher than that with 6 mg/kg/d (55%) (odds ratio = 2.69; 95% confidence interval, 1.11-6.4). Patients improved clinically and the treatments were equally well tolerated. The combination of aminosidine 12 mg/kg/d and sodium stibogluconate 20 mg/kg/d for 20 d appears to be an effective and safe replacement in Bihar for sodium stibogluconate alone for > or = 40 d.