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BACKGROUND: The control of Aedes aegypti (L.), the main urban vector that causes arboviral diseases such as dengue, Chikungunya and Zika, has proved to be a challenge because of a rapid increase in insecticide resistance. Therefore, adequate monitoring of insecticide resistance is an essential element in the control of Ae. aegypti and the diseases it transmits. We estimated the frequency and intensity (Resistance Frequency Rapid Diagnostic Test [F-RDT] and Resistance Intensity Rapid Diagnostic Test [I-RDT]) of pyrethroid resistance in populations of Ae. aegypti from Mexico using the bottle bioassay and results were related to the frequencies of knockdown resistance (kdr) mutations V1016I and F1534C. RESULTS: All populations under study were resistant to the pyrethroids: bifenthrin (99%), d-(cis-trans)-phenothrin (6.3% cis, 91.7% trans) and permethrin (99.5%) according to F-RDT, and showed moderate to high-intensity resistance at 10× the diagnostic dose (DD) in I-RDT. Frequencies of the kdr mutation V1016I in Ae. aegypti populations were correlated with moderate permethrin resistance at 10× DD, whereas F1534C mutation frequencies were correlated with high bifenthrin resistance at 5× DD. Both I1016 and C1535 were highly correlated with high-intensity phenothrin resistance at 1× to 10× DD. CONCLUSIONS: This study showed that high frequencies of kdr mutations V1016I and F1534C are reflected in the results of F-RDT and I-RDT tests. Bioassays in conjunction with the characterization of genetic resistance mechanisms are indispensable in the strategic and rational management of resistance in mosquitoes. © 2018 Society of Chemical Industry.

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BACKGROUND: The V1016I and F1534C mutations in the voltage-gated sodium channel gene have been associated with resistance to pyrethroids and DDT in Aedes aegypti mosquitoes. A study was carried out to determine the frequency of I1016 and C1534 by real-time PCR in five natural populations of Ae. aegypti in Venezuela during 2008, 2010 and 2012, as well as in a strain selected with 0.14 µg of deltamethrin for 15 generations. RESULTS: In natural populations, frequencies of I1016 varied between 0.01 and 0.37, and frequencies of C1534 between 0.35 and 1.0. In the Pampanito strain, the frequency of I1016 increased from 0.02 in F1 up to 0.5 in F15 and from 0.35 up to fixation for C1534 after selection with deltamethrin. CONCLUSION: The results showed that C1534 frequencies are higher than I1016 frequencies in natural populations of Ae. aegypti in Venezuela, and that deltamethrin selected the C1534 more rapidly than I1016.

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BACKGROUND: Temephos is an insecticide widely used in Venezuela to control the proliferation of the larvae of Aedes aegypti (L.), the principal vector of dengue virus. The aim of this study was to identify the susceptibility to temephos of Ae. aegypti in four locations in western Venezuela: Lara, Tres Esquinas, Ureña and Pampanito. Larval bioassays were conducted on samples collected in 2008 and 2010, and the levels of α- and ß-esterases, mixed-function oxidases, glutathione-S-transferase and insensitive acethyl cholinesterase were determined. RESULTS: Larval populations from western Venezuela obtained during 2008 and 2010 were found to be susceptible to temephos, with low resistance ratios and without overexpression of enzymes. CONCLUSIONS: The low RR values reveal the effectiveness of temephos in controlling the larval populations of Ae. aegypti. Control strategies must be vigorously monitored to maintain the susceptibility to temephos of these populations of Ae. aegypti.

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Resistance to the insecticides deltamethrin and malathion and the enzymes associated with metabolic resistance mechanisms were determined in four field populations of Aedes aegypti (L.) from western Venezuela during 2008 and 2010 using the bottle assay and the microplate biochemical techniques. For deltamethrin, mortality rates after 1 h exposure and after a 24-h recovery period were determined to calculate the 50% knock-downconcentration (KC50) and the lethal concentration (LC50), respectively. For malathion, mortality was recorded at 24 h to determine the LC50. For deltamethrin, resistance ratios of knock-down resistance and postrecovery were determined by calculating the RRKC50 and RRLC50, comparing the KC50 and LC50 values of the field populations and those of the susceptible New Orleans strain. Knock-down resistance to deltamethrin was moderate in the majority of the populations in 2008 (RRKC50 values were between 5- and 10-fold), and only one population showed high resistance in 2010 (RRKC50 > 10-fold). Moderate and high postrecovery resistance to deltamethrin was observed in the majority of the populations for 2008 and 2010, respectively. There was significantly increased expression of glutathione-S-tranferases and mixed-function oxidases. All populations showed low resistance to malathion in 2008 and 2010 with significantly higher levels of alpha-esterases for 2008 and 2010 and beta-esterases for 2008.

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Introducción: la fasciolosis, por Fasciola hepatica, muestra a escala mundial un incremento en la incidencia de enfermos en los últimos años. Cuba se encuentra entre aquellos países donde se reportan casos esporádicos y algunos brotes epidémicos. Objetivo: describir el comportamiento clínico-terapéutico de esta trematodiosis de trasmisión digestiva en una serie de 87 pacientes ingresados en el Instituto de Medicina Tropical "Pedro Kourí" desde enero de 1996 a diciembre de 2005. Método: los pacientes se dividieron en 2 grupos atendiendo al fármaco prescrito, dihidroemetina o triclabendazol. Se recogieron las variables clínicas al inicio del diagnóstico y 90 d después del tratamiento; se hallaron las medias y la desviación estándar. Resultados: el sexo masculino predominó discretamente con 54 por ciento en nuestra serie de pacientes ingresados en el servicio de medicina tropical del instituto. La ingestión de berro (Nasturtium officinale) estuvo presente en casi la mitad de los pacientes. El dolor abdominal, fiebre y astenia resultaron los síntomas de mayor frecuencia. El triclabendazol y la dihidroemetina fueron útiles en el tratamiento. Conclusiones: se comprobó la utilidad de los exámenes de laboratorio en el diagnóstico y seguimiento de los enfermos. Los antiparasitarios dihidroemetina y triclabendazol resultaron efectivos a las dosis utilizadas con efectos adversos menores.

Introduction: in the last few years, the Incidence rate of fascioliosis caused by Fasciola hepatica has increased worldwide. Cuba is one of the countries that have reported sporadic cases and also some outbreaks of fasciolosis. Objective: to describe clinical and therapeutic features of this trematodiasis of digestive transmission found in 87 patients, who had been admitted to "Pedro Kourí" Institute of Tropical Medicine from January 1996 to December 2005. Methods: patients were divided into 2 groups according to the prescribed drug, that is, triclabendazole and dihydroemetine. The clinical variables were collected at the time of diagnosis and 90 days after treatment; the means and the standard deviation were estimated. Results: males was slightly predominant (54) in our series of patients admitted to the institute service. Consumption of watercress (Nasturtium officinale) was found in almost half of the patients. Abdominal pain, fever and malaise were the most frequent symptoms. Both drugs were useful to treat F. hepatica. Conclusions: this study showed the usefulness of lab tests for diagnosis and follow-up of patients after treatment. The anti-parasitic drugs dihydroemetine and triclabendazole proved to be effective at the prescribed doses in this research with minor adverse effects.

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INTRODUCTION: in the last few years, the Incidence rate of fascioliosis caused by Fasciola hepatica has increased worldwide. Cuba is one of the countries that have reported sporadic cases and also some outbreaks of fasciolosis. OBJECTIVE: to describe clinical and therapeutic features of this trematodiasis of digestive transmission found in 87 patients, who had been admitted to "Pedro Kourí" Institute of Tropical Medicine from January 1996 to December 2005. METHODS: patients were divided into 2 groups according to the prescribed drug, that is, triclabendazole and dihydroemetine. The clinical variables were collected at the time of diagnosis and 90 days after treatment; the means and the standard deviation were estimated. RESULTS: males was slightly predominant (54) in our series of patients admitted to the institute service. Consumption of watercress (Nasturtium officinale) was found in almost half of the patients. Abdominal pain, fever and malaise were the most frequent symptoms. Both drugs were useful to treat F. hepatica. CONCLUSIONS: this study showed the usefulness of lab tests for diagnosis and follow-up of patients after treatment. The anti-parasitic drugs dihydroemetine and triclabendazole proved to be effective at the prescribed doses in this research with minor adverse effects.

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El dengue es un importante problema de salud pública en Venezuela, donde aedes aegypti es el principal vector. El propósito de este estudio fue determinar el estado de la susceptibilidad a la deltametrina en nueve poblaciones naturales de A. aegypti del estado Trujillo, en comparación con la cepa susceptible Rockefeller. Los bioensayos fueron llevados a cabo siguiendo la metodología de la Organización Mundial de la Salud. Las poblaciones Trujillo, Pampán, Pampanito, Flor de Patria, Motatán, Tres Esquinas y Cubita mostraron valores de mortalidades comprendidas entre 89% y 97%, y KDT50 entre 15,7 min y 24,1 min, sugiriendo la posibilidad de resistencia la cual debe ser confirmada. Las poblaciones Monay y Filo fueron susceptibles, con KDT50 de 15,5 y 20,2 min respectivamente, y mortalidades a las 24 horas de 99 y 98%. Estos resultados deben ser considerados al momento de diseñar el programa de control del vector para asegurar la efectividad del mismo.

Dengue is an important public health problem in Venezuela, where Aedes aegypti is the main vector. The purpose of this study was to determine the status of susceptibility to deltamethrin in nine natural populations of A. aegypti from Trujillo state compared with the susceptible Rockefeller strain. Bioassays were carried out following the methodology of the World Health Organization. The values of mortalities were found between 89% and 97%, allowing categorize the populations from Trujillo, Pampan, Pampanito, Flor de Patria, Motatan, Tres Esquinas and Cubita as resistant under verification, with values KDT50 between 15.7 min and 24.1 min, suggesting the possibility of resistance which must be confirmed and the populations from Monay and Filo as susceptible, with a KDT50 of 15.5 and 20.2 min, respectively, and 99 and 98% mortality at 24 hours. These results should be considered when designing programs for vector control to ensure those are effective to control A. aegytpti populations.

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Lutzomyia evansi es considerado un vector alterno de la leishmaniasis visceral americana (LVA) en localidades de Colombia y Venezuela. En el estado Trujillo, Venezuela, estudios sobre labionomía de esta especie han revelado que está asociada a los principales focos de LVA con tasas de infección natural de 0,23%, antropo filia y comportamiento intra y peridomiciliar, aspectos que nos motivaron a precisar bajo condiciones experimentales la respuesta de una población silvestre de esta especie frente a fenitrotión y lambdacialotrina para determinar las concentraciones letales 50 y 95 y dosis diagnósticas. La población de L. evansi fue capturada con trampa de Shannonen la localidad de Los Pajones, Estado Trujillo, por ser una localidad no sometida a presión con insecticidas. Los bioensayos fueron realizados por exposición de los insectos durante una hora a papeles impregnados con diferentes concentraciones de fenitrotión y lambdacialotrina y la mortalidad fue registrada luego de 24 horas. Las CL 50 y CL 95 con el insecticida fenitrotión fueron de 0,012% y 0,05% respectivamente y para lambdacyhalotrina una CL 50 de 0,0004% y CL 95 de 0,0017%. Los valores de las dosis diagnósticas obtenidos fueron de 0,189% para fenitrotión y 0,0063% para lambdacialotrina. Estos resultados son útiles para establecer comparaciones con otras poblaciones de L.evansi de áreas endémicas de LVA que estén sometidas a fuerte presión con insecticidas y así determinar las concentraciones que permitirían reducir la población de este vector e interrumpir la transmisión de la enfermedad.

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