Primer registro de triatóminos naturalmente infectados por Trypanosoma cruzi en el estado Bolívar, Venezuela / First record of naturally infected triatomines with trypanosoma cruzi, Bolivar state, Venezuela

La enfermedad de chagas o tripanosomiasis americana está adquiriendo cada vez mayor importancia en la región amazónica de Venezuela, en la cual hasta ahora se carecía de información de la presencia de trypanosoma cruzi en triatóminos, reservorios y humanos, particularmente para el estado Bolívar, el estado de mayor superficie del país, situado al sur del río Orinoco. Cuatro ejemplares de triatoma maculata fueron recolectados en el peridomicilio de la comunidad de Maniapure, en el municipio Cedeño. En dos de los ejemplares se determinó la infección natural por trypanosoma cruzi al examen al fresco de heces con presencia de tripomastigotos metacíclicos infectantes. Los parásitos fueron inoculados en modelos murinos y aislados en cultivos para su caracterización molecular. Se confirmó el diagnóstico de este parásito por pruebas parasitológicas y moleculares, caracterizándose los aislados como TcI. La importancia de estos hallazgos pioneros podría motivar el estudio de la transmisión vectorial de la enfermedad de chagas en este estado catalogado como no endémico.

American trypanosomiasis or chagas disease is becoming increasingly important in the Amazon region of Venezuela, in which up to now information was lacking of the presence of trypanosoma cruzi in triatomins, reservoirs and humans, particularly for Bolivar state, the state with the largest territory of the country, located in the south of the Orinoco river. Four specimens of triatoma maculata were collected in the peri-domiciliar area of the community of Maniapure, in the Cedeño municipality. Two of these individuals were found naturally infected with trypanosoma cruzi upon examination of fresh stool with presence of metacyclic trypomastigotes. Parasites were inoculated in murine models and isolated for molecular characterization. Parasite isolates were molecularly characterized as TcI. The importance of these pioneering findings should motivate the study of the vector or oral transmission of Chagas disease in this non endemic State of Venezuela.

Infección por Trypanosoma cruzi y polimorfismo del Citocromo B del ADN mitocondrial en Triatoma maculata de Anzoategui y Portuguesa, Venezuela / Trypanosoma cruzi infection and cytochrome b polimorphism of mitochondrial dna in Triatoma maculata of Anzoátegui and Portuguesa states, Venezuela

Con el fin de entender la dinámica poblacional de Triatoma maculata, se analizó el polimorfismo genético y los índices de infección con Trypanosoma cruzi, utilizando triatominos provenientes de ecotopos y regiones geográficas diferentes. El índice de infección parasitaria para T. maculata, fue de 29.8% a través de la observación directa al microscopio y 40.3% utilizando el método de reacción en cadena de la polimerasa. Los niveles de infección encontrados incrementan la importancia de T. maculata como vector involucrado en el ciclo de transmisión de T. cruzi. El análisis del polimorfismo de longitud de fragmentos de restricción de una región del gen Cyt B, permitió establecer en forma preliminar, diferencias en los patrones de bandas de este gen, según el origen geográfico de cada población. Esto puede asociarse a cambios relacionados con procesos adaptativos involucrados en la colonización de nuevos hábitats. No se observó variación genética para vectores capturados en diferentes ecotopos de una misma localidad. Sin embargo es evidente la participación del vector en el ciclo de transmisión, mostrando que la presencia de T. maculata en las casas no puede ser ignorada

In order to understand more about the populational dynamics of Triatoma maculata, the genetic polimorphism and the infection indexes of Trypanosoma cruzi were analysed, using triatomine obtained from different ecotopes and geographical regions. The parasitic infection index of T. maculata was 29.8% using the microscope direct observation, and 40.3% by the polymerase chain reaction method. Both methods were important for epidemiological screening of the vectors with low potential of infection. The amplification of one region the Cyt B gene of these organisms, followed by a restriction fragments length polymorphism analysis, allowed us to establish different patterns of bands according to the geographic origin of each population, which indicates the lack of migration between individuals of Portuguesa and Anzoátegui states. These genetic differences may be associated with changes in adaptative events involved in the colonization of new habitats. The lack of polymorphism among vectors collected in different habitats of the same region showed an important genetic flow which has epidemiological implications in the risk of transmission of the disease, showing that the presence of T. maculata in houses cannot be ignored

Commercial coconut palm as an ecotope of Chagas disease vectors in north-eastern Venezuela.

Background & objective: There are few reports of Coccus nucifera (Palmae) infestation by triatomines (Hemiptera, Reduviidae, Triatominae), vectors of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae), the causal agent of American Trypanosomiasis. The aim of this study was to determine if this palm is an appropriate ecotope for Rhodnius prolixus and Triatoma maculata, the main vectors in Venezuela. Methods: Dry and green leaves, humid debris, interfoliaceus meshes and bracts from C. nucifera from north-eastern Venezuela were examined for the presence of triatomines. Samples of the intestinal content of vectors, macerated in isotonic saline solution and haemolymph were examined microscopically for the presence of Trypanosoma spp. The parasites were isolated and characterized using biological parameters and PCR. Triatomine blood meal sources were determined using ELISA. Results: A total of 14 palms were examined in which viable eggs of both species of vectors were found in 13 palms (92.85%). A total of 242 R. prolixus and 144 T. maculata adults were collected, of which 98% of R. prolixus and 70% of T. maculata individuals were infected by T. cruzi (TcI genotype) and 13% of R. prolixus individuals showed a mixed infection with T. rangeli, the other American trypanosome. ELISA testing for possible triatomine blood-meal sources revealed that these vectors are essentially eurytrophic and zoophilic, although R. prolixus also eventually used human blood as a nourishment source. Interpretation & conclusion: The results obtained suggest that C. nucifera is an appropriate vegetal niche for these triatomine species in Venezuela. The presence of this commercial palm may represent a useful environmental bioindicator of risk for Chagas disease.

Estudio seroepidemiológico y entomológico sobre la enfermedad de Chagas en un área infestada por Triatoma maculata (Erichson 1848) en el centro-occidente de Venezuela / An entomological and seroepidemiological study of Chagas' disease in an area in central-western Venezuela infested with Triatoma maculata (Erichson 1848)

En el presente trabajo se realizó un estudio seroepidemiológico, entomológico y de factores de riesgo para la infestación de las viviendas en un área infestada por Triatoma maculata (Parroquia Xaguas, Municipio Urdaneta, Estado Lara, Venezuela). Se muestrearon 140 viviendas, 509 personas y 110 cánidos, a los cuales se les determinó anticuerpos séricos anti-Trypanosoma cruzi mediante ELISA y MABA, utilizando antígenos recombinantes. La infección por Tr. cruzi de los triatominos fue determinada por microscopía óptica y PCR. Los resultados mostraron una seroprevalencia en humanos de 1,57 por ciento y en cánidos de 6,36 por ciento. De los 545 triatominos capturados 97,98 por ciento fueron T. maculata, 1,65 por ciento Eratyrus mucronatus y 0,37 por ciento Panstrongylus geniculatus; con índices vectoriales de infección 0,36 por ciento, infestación 16,4 por ciento, colonización 39,1 por ciento, coinfestación 8,6 por ciento y dispersión 100 por ciento. La presencia de vectores en el domicilio y peridomicilio estuvo asociada a la presencia de gallinas, desorden en el peridomicilio, caprinos, gallineros y/o distribución del domicilio. Los resultados permiten concluir que T. maculata es el vector predominante en la región, con capacidad de infestar y colonizar el domicilio y estaría involucrado en la transmisión de la enfermedad de Chagas.

This article presents a study on seroepidemiological, entomologic, and risk factors for domiciliary infestation in a circumscribed area infested with Triatoma maculata in Parroquia Xaguas, Urdaneta Municipality, Lara State, Venezuela. One hundred and forty households, 509 persons, and 110 dogs were sampled. Serum anti-Trypanosoma cruzi antibodies were determined by means of ELISA and MABA techniques using recombinant antigens. Tr. cruzi infection in the triatomines was determined by direct microscopy and PCR. According to the results, 1.57 percent of humans and 6.36 percent of dogs were positive for serum anti-Tr. cruzi antibodies. Triatomine species were: 97.98 percent T. maculata, 1.65 percent Eratyrus mucronatus, and 0.37 percent Panstrongylus geniculatus. Vector indices were: 0.36 percent vector infection, 16.4 percent household infestation, 39.1 percent household colonization, 8.6 percent household co-infestation, and 100 percent vector dispersion. Domiciliary and peridomiciliary infestation was associated with the presence of chickens and disorderly goat corrals, chicken coops, and domiciliary distribution. The results strongly suggest that T. maculata is the predominant Tr. cruzi vector in the area and that due to its capacity to infest and colonize human dwellings, it could be involved in Chagas' disease transmission.

Biological aspects of crosses between Triatoma maculata (Erichson, 1848) and Triatoma pseudomaculata Corrêa & Espínola, 1964 (Hemiptera: Reduviidae)

Due to morphological similarities between Triatoma maculata and T. pseudomaculata, which comprise the "maculate complex", both had been regarded as the same species until 1964. Considering that the studies on triatomine hybridization permit hypotheses formulation concerning origin and divergence of species, enabling a quantitative analysis of taxonomic relationships between species, the present investigation was aimed at broadening further understanding related to the capacity of hybrid production by determining the degree of reproductive isolation between T. maculata and T. pseudomaculata. Our results have demonstrated that T. maculata and T. pseudomaculata showed no differences regarding reproduction patterns and they are able to cross, generating infertile hybrids.