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Background. The treatment of cutaneous leishmaniasis (CL) caused by leishmania braziliensis in Brazil with pentavalent antimony (Sb) is associated with a high rate of failure, up to 45% of cases. In addition, Sb can only administered parenterally and has important toxic effect. An effective, safe, and oral treatment for CL is required. Methods. A randomized controlled clinical trial was conducted to compare the efficacy and safety of high-dosage oral fluconazole (6.5–8.0 mg/kg/d for 28 days) versus a standard Sb protocol (20 mg/kg/d for 20 days) for the treatment of CL in Bahia, Brazil. Results. A total of 53 subjects were included in the trial; 26 were treated with Sb, and 27 with fluconazole. Intention-to-treat analysis showed initial cure rates (2 months after treatment) of 22.2% (6 of 27) in the fluconazole and 53.8% (14 of 26) in the Sb group (P = .04). Six months after treatment, the final cure rate remained the same in both groups, without any replaces. The frequencies of adverse effects in the Sb and fluconazole groups were similar, 34.6% versus 37% respectively. One patient treated with fluconazole discontinued treatment owing to malaise, headache, and moderate dizziness (Common Terminology Criteria for Adverse Events grade 2). Conclusions. Oral fluconazole at a dosage of 6.5–8 mg/kg/d for 28 days should not be considered an effective treatment for CL caused by L. braziliensis. Clinical Trials Registration. NCT01953744.

Leishmania parasites cause a broad spectrum of clinical disease. Here we report the sequencing of the genomes of two species of Leishmania : Leishmania infantum and Leishmania braziliensis . The comparison of these sequences with the published genome of Leishmania major reveals marked conservation of synteny and identifies only ∼200 genes with a differential distribution between the three species. L. braziliensis , contrary to Leishmania species examined so far, possesses components of a putative RNA-mediated interference pathway, telomere-associated transposable elements and spliced leader–associated SLACS retrotransposons. We show that pseudogene formation and gene loss are the principal forces shaping the different genomes. Genes that are differentially distributed between the species encode proteins implicated in host-pathogen interactions and parasite survival in the macrophage.

Chitinases, a group of glycosyl hydrolases (GHs), catalyze the degradation of chitin by releasing N-acetylglucosamine subunits. GHs can be found in all three domains of life. Among the three GH families (GH18, GH19, and GH20), GH18 chitinases are the most conserved and extensively studied. These enzymes have been implicated in nutrition, immune modulation, invasion, and virulence across diverse pathogens. In some parasitic protists, GH18 chitinases are essential for transmission. However, in kinetoplastids, including Leishmania spp., these enzymes remain poorly characterized. This study aimed to identify and characterize chitinase across kinetoplastids, with a particular focus on GH18 chitinase in Leishmania braziliensis , the causative agent of muco-cutaneous leishmaniasis. A bioinformatic pipeline was implemented to retrieve and annotate chitinase genes from multiple databases. Catalytic domains and subcellular localization were identified using dedicated computational tools. Phylogenetic relationships were reconstructed in MEGA12 using maximum likelihood and neighbor-joining methods. RNA-seq data were analyzed to evaluate stage-specific expression. Structural models of L. braziliensis GH18 chitinase (Lbr_ChGH18) were created with AlphaFold and subsequently refined. We identified GH18 chitinases genes across Leishmania species and other kinetoplastids, together with GH19 and GH20 chitinase genes. Lbr_ChGH18 was detected across all life-cycle stages, with peak levels in amastigotes. Docking analyses identified closantel, argifin, and argadin as potential inhibitors of Lbr_ChGH18. Epitope prediction revealed conserved B- and T-cell epitopes in GH18 chitinases from Old and New World Leishmania , capable of binding multiple HLA class I and II molecules, highlighting their potential as diagnostic and vaccine candidates. The discovery of GH20 chitinase-like genes in Trypanosoma species offers new insights into the evolution and functional diversification of GHs in kinetoplastids. The high conservation and expression of GH18 chitinases underscore their potential as promising targets for drug and vaccine development against leishmaniasis.

Cutaneous leishmaniasis (CL) is treated with parenteral drugs for decades with decreasing rate cures. Miltefosine is an oral medication with anti-leishmania activity and may increase the cure rates and improve compliance. This study is a randomized, open-label, controlled clinical trial aimed to evaluate the efficacy and safety of miltefosine versus pentavalent antimony (Sb(v)) in the treatment of patients with CL caused by Leishmania braziliensis in Bahia, Brazil. A total of 90 patients were enrolled in the trial; 60 were assigned to receive miltefosine and 30 to receive Sb(v). Six months after treatment, in the intention-to-treat analyses, the definitive cure rate was 53.3% in the Sb(v) group and 75% in the miltefosine group (difference of 21.7%, 95% CI 0.08% to 42.7%, p = 0.04). Miltefosine was more effective than Sb(v) in the age group of 13-65 years-old compared to 2-12 years-old group (78.9% versus 45% p = 0.02; 68.2% versus 70% p = 1.0, respectively). The incidence of adverse events was similar in the Sb(v) and miltefosine groups (76.7% vs. 78.3%). Vomiting (41.7%), nausea (40%), and abdominal pain (23.3%) were significantly more frequent in the miltefosine group while arthralgias (20.7%), mialgias (20.7%) and fever (23.3%) were significantly more frequent in the Sb(v) group. This study demonstrates that miltefosine therapy is more effective than standard Sb(v) and safe for the treatment of CL caused by Leishmania braziliensis in Bahia, Brazil. Clinicaltrials.gov Identifier NCT00600548.

The challenge of American tegumentary leishmaniasis (ATL) continues in Brazil, presenting a persistent public health issue despite initiatives aimed at public outreach, vector control and health education. To gain a deeper understanding of this disease, a study was conducted in an endemic region located in the northern region of the state of Minas Gerais, Brazil. The study monitored 30 resident patients diagnosed with ATL, using serum samples from 6 healthy individuals as controls. The localized cutaneous form of the disease was found to be predominant, with lesions appearing on various parts of the body and the majority of the affected individuals being male. The study found significantly higher levels of IgG anti- α -Gal antibodies in ATL-infected patients compared to healthy individuals. Treatment of 19 patients with meglumine antimoniate resulted in limited improvement in symptoms for most. Nonetheless, the study found that 12 patients who completed treatment with epithelialization of the lesions showed a significant decrease in IgG anti- α -Gal antibodies, indicating potential applications of this antibody in the diagnosis and monitoring of the disease. The study also identified Leishmania species in 7 analysed patients, revealing 6 cases infected by Leishmania braziliensis and 1 by L. infantum , with a significant difference in the anti- α -Gal responses. The findings of the study emphasize the urgent need for the development of human vaccines and innovative treatment strategies adapted to the diversity of Leishmania species causing cutaneous leishmaniasis and individual patient responses to improve the clinical management of ATL in Brazil and similar endemic regions.

Leishmaniases are neglected tropical diseases and Leishmania ( Leishmania ) infantum and Leishmania ( Viannia ) braziliensis are the most important causative agents of leishmaniases in the New World. These two parasite species may co-circulate in a given endemic area but their interactions in the vector have not been studied yet. We conducted experimental infections using both single infections and co-infections to compare the development of L . ( L .) infantum (OGVL/mCherry) and L . ( V .) braziliensis (XB29/GFP) in Lutzomyia longipalpis and Lutzomyia migonei . Parasite labelling by different fluorescein proteins enabled studying interspecific competition and localization of different parasite species during co-infections. Both Leishmania species completed their life cycle, producing infective forms in both sand fly species studied. The same happens in the co infections, demonstrating that the two parasites conclude their development and do not compete with each other. However, infections produced by L . ( L .) infantum reached higher rates and grew more vigorously, as compared to L . ( V .) braziliensis . In late-stage infections, L . ( L .) infantum was present in all midgut regions, showing typical suprapylarian type of development, whereas L . ( V .) braziliensis was concentrated in the hindgut and the abdominal midgut (peripylarian development). We concluded that both Lu. migonei and Lu. longipalpis are equally susceptible vectors for L . ( L .) infantum , in laboratory colonies. In relation to L . ( V .) braziliensis , Lu. migonei appears to be more susceptible to this parasite than Lu. longipalpis .

The protozoan parasite Leishmania spp. is a causative agent of leishmaniasis, a disease that affects millions of people in more than 80 countries worldwide. Apart from its medical relevance, this organism has a genetic organization that is unique among eukaryotes. Studies of the mechanisms regulating gene expression in Leishmania led us to investigate noncoding RNAs (ncRNAs) as regulatory elements. We previously identified differentially expressed (DE) ncRNAs in Leishmania braziliensis with potential roles in the parasite biology and development. Herein, we present a functional analysis of one such DE ncRNA, the 147-nucleotide-long transcript ncRNA97, which is preferentially expressed in amastigotes, the replicative form within mammalian phagocytes. By RT-qPCR the ncRNA97 was detected in greater quantities in the nucleus under physiological conditions and in the cytoplasm under nutritional stress. Interestingly, the transcript is protected at the 5’ end but is not processed by the canonical trypanosomatid trans -splicing mechanism, according to the RNA circularization assay. ncRNA97 knockout ( KO ) and addback ( AB ) transfectants were generated and subjected to phenotypic analysis, which revealed that the lack of ncRNA97 impairs the starvation response and differentiation to the infective form. Comparative transcriptomics of ncRNA97 KO and parental cells revealed that transcripts encoding amastigote-specific proteins were affected. This pioneering work demonstrates that ncRNAs contribute to the developmental regulatory mechanisms of Leishmania .

Human cutaneous leishmaniasis (CL) caused by Leishmania braziliensis, presents an exaggerated Th1 response that is associated with ulcer development. Macrophages are the primary cells infected by Leishmania parasites and both reactive oxygen species (ROS) and nitric oxide (NO) are important in the control of Leishmania by these cells. The mechanism involved in the killing of L. braziliensis is not well established. In this study, we evaluate the role of ROS and NO in the control of L. braziliensis infection by monocytes from CL patients. After in vitro infection with L. braziliensis, the oxidative burst by monocytes from CL patients was higher when compared to monocytes from healthy subjects (HS). Inhibition of the ROS pathway caused a significant decrease in the oxidative burst in L. braziliensis infected monocytes from both groups. In addition, we evaluated the intracellular expression of ROS and NO in L. braziliensis-infected monocytes. Monocytes from CL patients presented high expression of ROS after infection with L. braziliensis. The expression of NO was higher in monocytes from CL patients as compared to expression in monocytes from HS. A strong positive correlation between NO production and lesion size of CL patients was observed. The inhibition of ROS production in leishmania-infected monocytes from CL patients allowed the growth of viable promastigotes in culture supernatants. Thus, we demonstrate that while production of ROS is involved in L. braziliensis killing, NO alone is not sufficient to control infection and may contribute to the tissue damage observed in human CL.

Cutaneous and mucosal leishmaniasis, caused in South America by Leishmania braziliensis, is difficult to cure by chemotherapy (primarily pentavalent antimonials [Sbv]). Treatment failure does not correlate well with resistance in vitro, and the factors responsible for treatment failure in patients are not well understood. Many isolates of L. braziliensis (>25%) contain a double-stranded RNA virus named Leishmaniavirus 1 (LRV1), which has also been reported in Leishmania guyanensis, for which an association with increased pathology, metastasis, and parasite replication was found in murine models. Here we probed the relationship of LRV1 to drug treatment success and disease in 97 L. braziliensis-infected patients from Peru and Bolivia. In vitro cultures were established, parasites were typed as L. braziliensis, and the presence of LRV1 was determined by reverse transcription-polymerase chain reaction, followed by sequence analysis. LRV1 was associated significantly with an increased risk of treatment failure (odds ratio, 3.99; P = .04). There was no significant association with intrinsic SbV resistance among parasites, suggesting that treatment failure arises from LRV1-mediated effects on host metabolism and/or parasite survival. The association of LRV1 with clinical drug treatment failure could serve to guide more-effective treatment of tegumentary disease caused by L. braziliensis.

Background. Cutaneous leishmaniasis is an ultimately self-curing disease for which systemic therapy with pentavalent antimony (Sb) is effective but with side effects. We evaluated 2 local treatments, intralesional (IL) Sb and cryotherapy, for single lesions due to Bolivian Leishmania (v.) braziliensis in a placebo-controlled study. Methods. Patients were randomized between IL Sb (650 μg/mm2 of lesion area on days 1, 3, and 5), cryotherapy (days 1 and 14), and placebo cream (daily for 20 days) in a 3:2:3 allocation. Lesion area was measured prior to therapy, and at 1, 3, and 6 months after therapy. The criteria for lesion cure were as follows: not doubling in size at 1 month, at least 50% diminution in size at 3 months, and complete reepithelialization at 6 months. Local adverse effects were recorded. Results. Cure rates were 21 of 30 (70%; 95% confidence interval [CI], 52%–83%) for IL Sb, 4 of 20 (20%; 95% CI, 8%–42%) for cryotherapy, and 5 of 30 (17%; 95% CI, 7%–34%) for placebo cream (P < .001 for IL Sb vs each other group). IL Sb adverse events were limited to injection site pain, with a mean value of 1.0 (mild). Conclusions. The comparative cure rate, small amount of drug administered, and tolerance data for IL Sb suggest that if local therapy for single L. braziliensis lesions is chosen, this treatment is attractive. Given the difficulties of performing placebo-controlled trials in the New World, the combined placebo and cryotherapy cure rate (18%; 95% CI, 10%–31%) is likely to become the standard against which future interventions for L. braziliensis are compared. Clinical Trials Registration. NCT01300975.