ABSTRACT
Human-made and environmental changes constitute a major risk factor for the (re-)emergence and spread of leishmaniasis; surveillance of the transmission cycle is essential in this context. This study integrated entomological and molecular parasitological techniques to document the transmission pattern of a peridomestic focus of Leishmania in the Isiboro Secure area of Bolivia. First the spatial distribution and relative density of phlebotomine sand flies, genus Lutzomyia, were established. Lutzomyia shawi was the predominant species in domestic and peridomestic environments (90% from all collections). Second, direct application of the hsp70 PCR to sand fly extracts detected Leishmania infections in Lu. shawi only, and gave an estimated infection rate of 0.21 to 0.38%. The cleavage of the hsp70 amplicon with restriction enzymes (hsp70 PCR-RFLP) allowed identification of Le. (V.) braziliensis and Le. (V.) guyanensis in Lu. shawi captured in the same village. These two parasite species were also found in humans from the study region, supporting the co-existence of two transmission cycles involving the same sand fly species. This study demonstrated the use of PCR-RFLP in the identification of Leishmania in sand fly pools which could lead to the development of methods for screening large sand fly populations in Latin America.
Subject(s)
Insect Vectors/parasitology , Leishmania braziliensis/isolation & purification , Leishmania guyanensis/isolation & purification , Leishmaniasis, Cutaneous/transmission , Psychodidae/parasitology , Animals , Bolivia , Female , Humans , Polymerase Chain Reaction , Polymorphism, Restriction Fragment LengthABSTRACT
Species identification is highly relevant for improved prognosis and adequate treatment of American tegumentary leishmaniasis (ATL). PCR-based methods are available for this purpose but should be simplified to improve accessibility. As a first step in this process, this paper describes a simplified protocol for collection of clinical samples. Using samples from 44 Bolivian patients with confirmed ATL, we demonstrated that hsp70 PCR-RFLP on skin scrapings collected with a tooth pick allowed identification of the parasite species with a sensitivity of 95% and specificity of 100%. Our method should greatly facilitate individual patient management and epidemiological surveillance of ATL.
Subject(s)
Leishmania/classification , Leishmaniasis, Cutaneous/parasitology , Animals , DNA, Protozoan/genetics , HSP70 Heat-Shock Proteins/genetics , Humans , Leishmania/genetics , Leishmania/isolation & purification , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length , Protozoan Proteins/genetics , Reproducibility of Results , Sensitivity and Specificity , Skin/parasitology , Specimen Handling/methodsABSTRACT
BACKGROUND: Antimonials are the first drug of choice for the treatment of American tegumentary leishmaniasis (ATL); however, their efficacy is not predictable, and this may be linked to parasite drug resistance. We aimed to characterize the in vitro antimony susceptibility of clinical isolates of Peruvian patients with ATL who were treated with sodium stibogluconate and to correlate this in vitro phenotype with different treatment outcomes. METHODS: Thirty-seven clinical isolates were obtained from patients with known disease and treatment histories. These isolates were typed, and the susceptibility of intracellular amastigotes to pentavalent (SbV) and trivalent (SbIII) antimonials was determined. RESULTS: We observed 29 SbV-resistant isolates among 4 species of subgenus Viannia, most of which exhibited primary resistance; isolates resistant only to SbIII; and 3 combinations of in vitro phenotypes: (1) parasites sensitive to both drugs, (2) parasites resistant to both drugs, and (3) parasites resistant to SbV only (the majority of isolates fell into this category). There was no correlation between in vitro susceptibility to both antimonials and the clinical outcome of therapy. CONCLUSION: Antimony insensitivity might occur in a stepwise fashion (first to SbV and then to SbIII). Our data question the definition of true parasite resistance to antimonials. Further studies of treatment efficacy should apply standardized protocols and definitions and should also consider host factors.
Subject(s)
Antimony Sodium Gluconate/pharmacology , Antiprotozoal Agents/pharmacology , Drug Resistance , Leishmania/drug effects , Leishmaniasis, Cutaneous/drug therapy , Animals , Antimony Sodium Gluconate/administration & dosage , Antimony Sodium Gluconate/therapeutic use , Antiprotozoal Agents/administration & dosage , Antiprotozoal Agents/therapeutic use , Humans , Leishmania/isolation & purification , Leishmaniasis, Cutaneous/epidemiology , Leishmaniasis, Cutaneous/parasitology , Parasitic Sensitivity Tests , Peru/epidemiology , Prospective Studies , Treatment OutcomeABSTRACT
Se realizó un estudio prospectivo, analítico y experimental para determinar el porcentaje de sensibilidad de un nuevo medio de cultivo para el diagnóstico de Leishmania, denominado TSTB (Torrico-Solano-Torrico-Bermúdez). Se obtuvieron las muestras por aspirado de úlceras con sospecha clínica de Leishmaniasis de pacientes provenientes del trópico de Cochabamba. Los objetivos planteados fueron determinar el porcentaje de sensibilidad del cultivo ya mencionado y analizar el crecimiento de parásitos de Leishmania. Como resultados se obtuvo un 90% de sensibilidad mediante este método diagnóstico y una mínima contaminación por hongos (mohos y levaduras); además, un cambio de coloración en el medio de cultivo debido al crecimiento y multiplicación de los parásitos por consumo de los nutrientes.
A prospective, analytic and experimental study was realized, in which we tried to determine the percentage of sensitive of a new culture medium for the diagnosis of Leishmania, denominated Torrico-Solano-Torrico-Bermudez (TSTB). Samples were obtained by a piration of ulcers with clinical suspicion of Leishmaniasis from patients proceeding from the tropical area of Cochabamba. The objectives planted were to determine the percentage of sensitive of the mentioned culture and to analyze the growth of the parasites of Leishmania. As a result, a 90 % of positivity was obtained with this diagnostic method, with a minimum contamination by fungus (moss and yeast); further more, a change in the colour of culture medium was observed, because of the growth and multiplication of the parasites by consumption of the nutrients.
Subject(s)
LeishmaniasisABSTRACT
PCR-restriction fragment length polymorphism analysis of heat shock protein 70 genes discriminates most neotropical Leishmania species, as well as Trypanosoma cruzi. The assay, combined with capillary electrophoresis in a microchip device, may be applied directly on clinical samples with a high sensitivity, hence supporting clinical and epidemiological monitoring of leishmaniasis.
Subject(s)
Genes, Protozoan , HSP70 Heat-Shock Proteins/genetics , Leishmania/classification , Leishmania/genetics , Polymerase Chain Reaction/methods , Protozoan Proteins/genetics , Animals , Base Sequence , DNA Primers/genetics , DNA, Protozoan/genetics , Humans , Leishmania/isolation & purification , Leishmaniasis/parasitology , Oligonucleotide Array Sequence Analysis , Polymerase Chain Reaction/statistics & numerical data , Polymorphism, Restriction Fragment Length , Sensitivity and SpecificityABSTRACT
We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4-7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments.
Subject(s)
Triatoma/genetics , Animals , Chagas Disease/genetics , Disease Vectors/classification , Female , Flow Cytometry , Male , South America , Triatoma/classificationABSTRACT
La preparación de este manual de operaciones de campo responde a esa necesidad, en él que queremos dar la información básica de la estructura del programa de control, los puntos importantes de información a la comunidad, especificar las acciones de cada uno de los componentes de las brigadas de campo y de laboratorio en el transcurso de las diferentes etapas que son: la línea de base, el mejoramiento de las viviendas y el uso de químicos. Este manual no pretende ser una guía definitiva sino más bien consideramos que es inicio de una sistematización de todas las actividades en función al logro del objetivo. En el futuro se espera enriquecer este manual con la experiencia adquirida por cada uno de los funcionarios pues su aporte será de mucho valor
Subject(s)
Chagas Cardiomyopathy , Chagas Disease , Triatoma , Bolivia , Entomology , Hemolymph , Host-Parasite Interactions , ParasitologyABSTRACT
Se ha efectuado un estudio de las prevalencias de las diferentes etapas de la leishmaniasis tegumentaria en 11 localidades (colonias) agrupadas en dos centrales sindicales con historia de asentamiento de antiguedad diferente en Carrasco tropical del Departamento de Cochabamba. La prevalencia de ulceras cutaneas puras mas las combinadas con cicatrices (Infecciones anteriores) fue 4.6 por ciento en 24 de Octubre (colonias mas recientes) y 1.9 por ciento en Tamboradas. La prevalencia de cicatrices cutaneas puras fue de 11.5 por ciento en 24 de Octubre y 15.8 por ciento en Tamboradas. 1 solo paciente con lesiones mucosas en 24 de Octubre (prev 0.8 por ciento ) y 2 en Tamboradas (prev 0.9 por ciento ) fueron encontrados.
