Genetic typing reveals monomorphism between antimony sensitive and resistant Leishmania donovani isolates from visceral leishmaniasis or post kala-azar dermal leishmaniasis cases in India

Population structures of Leishmania infantum and Leishmania tropica the causative agents of kala-azar in Southwest Iran

Visceral leishmaniasis (VL) is endemic in Iran and is caused predominantly by Leishmania infantum, but L. tropica is emerging as an important cause. We studied the intra-species population structure of Leishmania spp. causing VL in southwest Iran by sequence analysis of the internal transcribed spacer (ITS) 1 of DNA samples from 29 bone marrow aspiration smears. L. infantum (n = 25) and L. tropica (n = 4) were identified, consisting of 10 and three ITS1 sequence types (STs), respectively. Compared to GenBank ITS1 STs, our L. infantum parasites displayed high heterogeneity but less heterogeneity compared than northwest Iranian isolates. VL affects mostly nomadic populations in southwest Iran, and their mobility may explain partly the L. infantum heterogeneity. The VL causing L. tropica was also genetically heterogeneous but genetically indistinguishable from L. tropica strains causing anthroponotic cutaneous leishmaniasis from southwest Iran.

A new cost and time effective method for multilocus microsatellite typing (MLMT) studies: Application of Leishmania tropica isolates and clinical samples from Turkey

Molecular techniques are widely used in the field of parasitology to identify the genetic profile of the microbiological agents. Microsatellite typing studies are comprised of the amplification of polymorphic markers to analyze the fragment sizes using bioinformatics tools. Current methods need fluorescently labeled primers and size markers to obtain fragment peaks in ABI PRISM® systems and due to low discrimination power of gel-electrophoresis, it is not possible to differentiate primer-dimers from small fragments In the present study, we designed a new method for fragment analysis studies, which reduce the time by eliminating the classical PCR, the gel-electrophoresis and the preparation steps of fragment analysis. Ten previously studied Leishmania tropica strains and one Giemsa-stained slide were tested by new method and obtained fragment peaks were compared to the previous data obtained from ABI PRISM® system. Overall twelve makers were tested and the signal peak from each fragment was compared to classical ABI PRISM®-based fragment analysis and noted as identical. The new protocol is time saving, cost effective, and eliminates the human error comparing to classical MLMT analysis protocol. We believe that this method enables the easy detection of the fragment lengths without having bioinformatics experience and the obtained data can be easily shared with other laboratories.

Drug Targeting to Macrophages With Solid Lipid Nanoparticles Harboring Paromomycin: an In Vitro Evaluation Against L. major and L. tropica

Leishmaniasis is a worldwide disease that leads to high mortality and morbidity in human populations. Today, leishmaniasis is managed via drug therapy. The drugs that are already in clinical use are limited to a number of toxic chemical compounds and their parasite drug resistance is increasing. It is therefore essential, in order to circumvent the current difficulties, to design a new anti-leishmanial drug treatment strategy. Besides producing new, active anti-leishmanial entities, another promising strategy could be developing novel delivery systems and formulations of the existing pharmaceutical ingredients to improve drug efficacy. In the present study, paromomycin sulfate (PM), as one of the promising anti-leishmanial drugs, was formulated in solid lipid nanoparticles (SLN), and its in vitro efficacy was investigated against different strains of Leishmania using a MTT test, Parasite-Rescue-Transformation-Assay, SYTO Green staining, and fluorescent microscope imaging. The results show that PM-loaded SLN is significantly more effective than PM in inhibiting parasite propagation (P < 0.05) and that cytotoxicity of PM-SLN formulations is size dependent. According to our results, delivery of the drugs to the macrophages via nanoparticle utilization seems to be an accessible and practical approach.

The immunology of post-kala-azar dermal leishmaniasis (PKDL)

Post-kala-azar dermal leishmaniasis (PKDL) is a common complication of visceral leishmaniasis (VL) caused by Leishmania donovani. Because of its possible role in transmission it is considered a public health problem in VL endemic areas. The clinical features include a skin rash consisting of macules, papules or nodules in an otherwise healthy individual; this presentation is determined by the immune response towards parasites in the skin that probably persisted from the previous VL episode. The immune response in VL, cured VL and PKDL is the result of changes in the cytokine profile that only in part can be captured under the Th1 and Th2 dichotomy. Regulatory T cells and Th 17 cells also play a role. VL is characterized by an absent immune response to Leishmania with a predominantly Th2 type of response with high levels of IL-10; after successful treatment the patient will be immune with in vitro features of a Th1 type of response and in vivo a positive leishmanin skin test. PKDL takes an intermediate position with a dissociation of the immune response between the skin and the viscera, with a Th2 and Th1 type of response, respectively. It is likely that immune responses determine the different epidemiological and clinical characteristics of PKDL in Asia and Africa; various risk factors for PKDL may influence this, such as incomplete and inadequate treatment of VL, parasite resistance and genetic factors. It should be noted that PKDL is a heterogeneous and dynamic condition and patients differ with regard to time of onset after visceral leishmaniasis (VL), chronicity, extent and appearance of the rash including related immune responses, all of which may vary over time. Better understanding of these immune responses may offer opportunities for manipulation including combined chemotherapy and immunotherapy for VL to prevent PKDL from occurring and similarly in the treatment of chronic or treatment resistant PKDL cases.

Multilocus microsatellite typing of Leishmania and clinical applications: a review

Microsatellite markers have been used for Leishmania genetic studies worldwide, giving useful insight into leishmaniasis epidemiology. Understanding the geographic distribution, dynamics of Leishmania populations, and disease epidemiology improved markedly with this tool. In endemic foci, the origins of antimony-resistant strains and multidrug treatment failures were explored with multilocus microsatellite typing (MLMT). High genetic variability was detected but no association between parasite genotypes and drug resistance was established. An association between MLMT profiles and clinical disease manifestations was highlighted in only three studies and this data needs further confirmation. At the individual level, MLMT provided information on relapse and reinfection when multiple leishmaniasis episodes occurred. This information could improve knowledge of epidemiology and guide therapeutic choices for active chronic visceral leishmaniasis, the disease form in some HIV-positive patients.

Heterogeneity of the internal transcribed spacer region in Leishmania tropica isolates from southern Iran

Most of cutaneous leishmaniasis cases occur in only 7 countries, including Iran. Leishmania tropica is the main cause of anthroponotic cutaneous leishmaniasis in Iran. In order to study the heterogeneity and phylogeny of L. tropica in southern Iran, a total of 61 isolates were obtained from Bam district and the cities Kerman and Shiraz. The internal transcribed spacer (ITS) from the ribosomal DNA locus was amplified and then analysed by sequencing. Analysis of the ITS sequences showed four haplotypes in the isolates, including 3 haplotypes among the 58 isolates from the south eastern region, including Bam district and Kerman city, and 2 haplotypes among the 3 isolates from Shiraz city. The results showed a monophyletic structure for the south eastern population. In comparison to GenBank sequences of L. tropica from different countries, most of the southeast Iranian and Indian isolates are comprised in one cluster, while isolates from other countries and few other Iranian isolates group in a different cluster. Analysis of ITS sequences of south eastern L. tropica showed a homogeneous population which could be the basis for other molecular epidemiology studies using more discriminative markers and tracing possible changes in the population structure of L. tropica.

Treatment-based strategy for the management of post-kala-azar dermal leishmaniasis patients in the Sudan

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis that affects more than 50% of successfully treated visceral leishmaniasis (VL) patients in Sudan. PKDL is considered an important reservoir for the parasite and its treatment may help in the control of VL. Currently, treatment is mainly with sodium stibogluconate (SSG), an expensive and fairly toxic drug and without universally in treatment protocols used. A literature review, a consensus of a panel of experts, and unpublished data formed the basis for the development of guidelines for the treatment of PKDL in the Sudan. Six treatment modalities were evaluated. Experts were asked to justify their choices based on their experience regarding of drug safety, efficacy, availability, and cost. The consensus was defined by assigning a categorical rank (first line, second line, third line) to each option. Regarding the use of AmBisome the presence of the drug in the skin was confirmed in smears from PKDL lesions. Recommendations: AmBisome at 2.5 mg/kg/day/20 days or SSG at 20 mg/kg/day/40 days plus four/weekly intradermal injection of alum-precipitated autoclave L. major vaccine are suggested as first- and second-treatment options for PKDL in the Sudan, respectively. SSG at 20 mg/Kg/day/60 or more days can be used if other options are not available.