American cutaneous leishmaniasis (ACL) is a complicated disease producing about 67.000 new cases per year. The severity of the disease depends on the parasite species; however in the vast majority of cases species confirmation is not feasible. WHO suggestion for ACL produced by Leishmania braziliensis, as first line treatment, are pentavalent antimonial derivatives (Glucantime or Sodium Stibogluconate) under systemic administration. According to different authors, pentavalent antimonial derivatives as treatment for ACL show a healing rate of about 75% and reasons for treatment failure are not well known. In order to characterise the clinical and parasitological features of patients with ACL that did not respond to Glucantime, a cross-sectional observational study was carried out in a cohort of 43 patients recruited in three of the Colombian Army National reference centers for complicated ACL. Clinical and paraclinical examination, and epidemiological and geographic information were recorded for each patient. Parasitological, histopathological and PCR infection confirmation were performed. Glucantime IC₅₀ and in vitro infectivity for the isolated parasites were estimated. Predominant infecting Leishmania species corresponds to L. braziliensis (95.4%) and 35% of the parasites isolated showed a significant decrease in in vitro Glucanatime susceptibility associated with previous administration of the medicament. Lesion size and in vitro infectivity of the parasite are negatively correlated with decline in Glucantime susceptibility (Spearman: r = (-)0,548 and r = (-)0,726; respectively). A negative correlation between lesion size and parasite resistance is documented. L. braziliensis was found as the main parasite species associated to lesion of patients that underwent treatment failure or relapse. The indication of a second round of treatment in therapeutic failure of ACL, produced by L. braziliensis, with pentavalent antimonial derivatives is discussable. Cutaneous leishmaniasis is tropical and subtropical worldwide vector-borne disease produced by protozoan parasites from the genus Leishmania that include over 20 species and produce an estimated 0.7 million to 1.3 million new cases annually. The disease features are dependent on the patient immunological stage, the parasite biology and to some extent are determined by the geographic regions in which it occurs. New World cutaneous infections known as American Cutaneous Leishmaniasis (ACL) are associated with metastatic sequelae and treatment failure. In the present study we found that in patients with ACL infected in the Colombian Amazon and Orinoco regions and not responding to Glucantime treatment, the predominant species was L. braziliensis. In addition 35% of these lesion-isolated parasites show some level of drug resistance. We also found that these resistant parasites display reduced competence when infecting the human monocytic cell line U-937 in “in vitro” tests and are associated with lesions of reduced size. According to our findings the indication for a second round of treatment with pentavalent antimonial derivatives in patients with ACL that did not respond to the first round of treatment is arguable.

Background: African trypanosomes belong to a eukaryotic lineage which displays many unusual genetic features. The mechanisms of chromosome segregation in these diploid protozoan parasites are poorly understood. Centromeres in Trypanosoma brucei have been localised to chromosomal regions that contain an array of ~147 bp AT-rich tandem repeats. Initial estimates from the genome sequencing project suggested that these arrays ranged from 2 - 8 kb. In this paper, we show that the centromeric repeat regions are much more extensive. Results: We used a long-range restriction endonuclease mapping approach to more accurately define the sizes of the centromeric repeat arrays on the 8 T. brucei chromosomes where unambiguous assembly data were available. The results indicate that the sizes of the arrays on different chromosomes vary from 20 to 120 kb. In addition, we found instances of length heterogeneity between chromosome homologues. For example, values of 20 and 65 kb were obtained for the arrays on chromosome 1, and 50 and 75 kb for chromosome 5. Conclusions: Our results show that centromeric repeat arrays on T. brucei chromosomes are more similar in size to those of higher eukaryotes than previously suspected. This information provides a firmer framework for investigating aspects of chromosome segregation and will allow epigenetic features associated with the process to be more accurately mapped.

The discrimination of Leishmania species from patient samples has epidemiological and clinical relevance. In this study, different gene target PCR-restriction fragment length polymorphism (RFLP) protocols were evaluated for their robustness as Leishmania species discriminators in 61 patients with cutaneous leishmaniasis. We modified the hsp70 -PCR-RFLP protocol and found it to be the most reliable protocol for species identification.

Leishmania RNA virus (LRV) is a double-stranded RNA virus belonging to the Totiviridae family detected as cytoplasmic inclusions in some strains of the human parasite Leishmania spp. Experimental evidence supports the hypothesis that human coinfection with Leishmania spp.–LRV triggers an exacerbated immune response in the host that can be responsible for the observed complicated outcomes in cutaneous leishmaniasis (CL), such as mucosal leishmaniasis (ML) and treatment failure of CL. However, the reported frequencies of LRV associated with complicated outcomes in patient’s series are highly variable, diminishing the relevance on the virus presence in the pathogenesis of the disease. To assess whether or not the inconsistent information about the frequency of LRV associated with CL complicated outcomes could be related to the virus detection approach, the present study evaluated the LRV presence in clinical samples using a diagnostic algorithm according to the type of the sample. In 36 samples with diagnosis of complicated forms of CL (15 of ML and 21 of CL antimony treatment failure) and six samples with non–Leishmania spp. infection, the LRV presence was assessed by RT-PCR, RT-qPCR, and nested RT-PCR. Viral load was estimated in parasite clinical isolates. By combining the methods, LRV1 presence was confirmed in 45% (9/20) of isolates and 37.5% (6/16) of the incisional biopsies. Remarkably, in some cases (4/8), LRV1 was undetectable in the isolates but present in their respective biopsies, and less frequently, the opposite was observed (1/8), suggesting the possibility of loss of parasites harboring LRV1 during the in vitro growth.

Leishmaniasis is an important public health problem worldwide, with a broad spectrum of clinical and epidemiological features partly associated with the diversity and complex life cycle of the Leishmania parasites. This study analyzes genomic data from 205 Leishmania (Viannia) samples, including 65 newly sequenced clinical isolates. It also provides chromosome-level genome assemblies for 10 isolates representing different species and populations. The observed distribution of Leishmania genomic diversity across the sampling locations suggests rapid adaptation to different ecosystems. The phylogenomic analysis provides new hypotheses challenging the current delimitation of species. Pangenomic analysis of high-quality assemblies shows consistent copy number variation between species for different gene families. Larger and more diverse amastin gene families were observed in the assembled genomes compared to previous reports based on the analysis of short-read data. This work provides genomic resources and helpful information regarding central problems in the biology of Leishmania spp, including species diversification, transmission dynamics, and the evolution of virulence mechanisms.