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Resistance to insecticides is one of the great challenges that vector control programs must face. The constant use of pyrethroid-type insecticides worldwide has caused selection pressure in populations of the Aedes aegypti vector, which has promoted the emergence of resistant populations. The resistance mechanism to pyrethroid insecticides most studied to date is target-site mutations that desensitize the voltage-gated sodium channel (VGSC) of the insect to the action of pyrethroids. In the present study, susceptibility to the pyrethroid insecticides permethrin, lambda-cyhalothrin, and deltamethrin was evaluated in fourteen populations from the department of Córdoba, Colombia. The CDC bottle bioassay and WHO tube methods were used. Additionally, the frequencies of the F1534C, V1016I, and V410L mutations were determined, and the association of resistance with the tri-locus haplotypes was examined. The results varied between the two techniques used, with resistance to permethrin observed in thirteen of the fourteen populations, resistance to lambda-cyhalothrin in two populations, and susceptibility to deltamethrin in all the populations under study with the CDC method. In contrast, the WHO method showed resistance to the three insecticides evaluated in all populations. The frequencies of the mutated alleles ranged from 0.05-0.43 for 1016I, 0.94-1.0 for 1534C, and 0.01-0.59 for 410L. The triple homozygous mutant CIL haplotype was associated with resistance to all three pyrethroids evaluated with the WHO bioassay, while with the CDC bioassay, it was only associated with resistance to permethrin. This study highlights the importance of implementing systematic monitoring of kdr mutations, allowing resistance management strategies to be dynamically adjusted to achieve effective control of Aedes aegypti.

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Aedes albopictus is considered a potential vector of arboviruses in Colombia. Females and males naturally infected with dengue, Zika and chikungunya viruses have already been found in this country. We document the first record of Ae. albopictus in the Cordoba department, in North of Colombia. The finding was carried out during Ae. aegypti collection activities in the Ayapel, Montelibano, Planeta Rica, Pueblo Nuevo and Puerto Libertador municipalities. The entomological material was collected in water containers such as cement water tanks, tanks, bottles, tires, abandoned toilets, and plastic lids with natural water located in the intradomicile, peridomicile, and extra-domicile spaces of the homes. We collected 658 Ae. albopictus samples in the larva and pupa stages, and once these reached adulthood, we determined that 389 were female and 269 were male. This is the first record of the presence of Ae. albopictus in the Cordoba department.

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Introduction. Dengue is a public health problem in La Guajira region. Control has focused on the vector using insecticides, including organophosphates. Objective. To evaluate the state of susceptibility to organophosphates insecticides in fifteen Aedes aegypti (L.) populations in La Guajira, Colombia. Materials and methods. We collected samples of third-instar larvae and adult mosquitoes of Ae. aegypti in the municipalities of Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita, Villanueva. Bioassays for temefos, malathion, and pirimiphos-methyl were carried out following the methodology of the World Health Organization, and the bottle technique using the guidance of the Centers for Disease Control and Prevention. Susceptibility to temefos was determined through the resistance ratio between lethal concentration 50 and lethal concentration 95; for the compounds temefos, malathion and pirimiphos-methyl, susceptibility was calculated using diagnostic dose and diagnostic time in the populations evaluated. Rockefeller susceptible strain was used as a control. Results: All evaluated populations of Ae. aegypti from La Guajira were found to be susceptible to temefos (ratio resistance to CL50<5.0; ratio resistance to CL95<5.0; 98 - 100 % mortality); pirimiphosmethyl (99 - 100 % mortality), and malathion (100 % mortality). Conclusion. Based on the results, the use of temefos, malathion, and pirimiphosmethyl is feasible for the control of Ae. aegypti in the evaluated populations.

Introducción. El dengue es un problema de salud pública para el departamento de La Guajira. El control se ha enfocado en el vector con el uso de insecticidas, entre ellos los organofosforados. Objetivo. Evaluar el estado de la sensibilidad a insecticidas organofosforados de quince poblaciones de Aedes aegypti (L.) en el departamento de La Guajira, Colombia. Materiales y métodos. Se realizaron bioensayos para temefos, malatión y metil-pirimifos en larvas de tercer estadio y mosquitos adultos de Ae. aegypti en los municipios de Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita y Villanueva, siguiendo la metodología de la Organización Mundial de la Salud (OMS) y la técnica de botellas usando la guía de los de los Centers for Disease Control and Prevention, respectivamente. Se determinó la sensibilidad por medio de la razón de resistencia a CL50 y CL95 (RRCL50, RRCL95) para temefos y a dosis y tiempo diagnóstico para temefos, malatión y metilpirimifos en las poblaciones de campo evaluadas, usando como control la cepa sensible Rockefeller. Resultados. Las 15 poblaciones del departamento de La Guajira son sensibles a: temefos (razón de la resistencia a RRCL50<5,0; relación de resistencia a CL95<5,0; 98 a 100 % de mortalidad); metil-pirimifos (99 a 100 % de mortalidad) y malatión (100 % de mortalidad). Conclusión. Con base en los resultados obtenidos, es factible el uso de temefos, malatión y metil-pirimifos para el control de Ae. aegypti en las poblaciones evaluadas.

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Introducción. El dengue es un problema de salud pública para el departamento de La Guajira. El control se ha enfocado en el vector con el uso de insecticidas, entre ellos los organofosforados. Objetivo. Evaluar el estado de la sensibilidad a insecticidas organofosforados de quince poblaciones de Aedes aegypti (L.) en el departamento de La Guajira, Colombia. Materiales y métodos. Se realizaron bioensayos para temefos, malatión y pirimifos- metil en larvas de tercer estadio y mosquitos adultos de Ae. aegypti en los municipios de Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita y Villanueva, siguiendo la metodología de la Organización Mundial de la Salud (OMS) y la técnica de botellas usando la guía de los de los Centers for Disease Control and Prevention, respectivamente. Se determinó la sensibilidad por medio de la relación de resistencia a CL50 y CL95 (RRCL50, RRCL95) para temefos y a dosis y tiempo diagnóstico para temefos, malatión y pirimifos-metil en las poblaciones de campo evaluadas, usando como control la cepa sensible Rockefeller. Resultados. Las 15 poblaciones del departamento de La Guajira son sensibles a: temefos (relación de la resistencia a CL50<5,0; relación de resistencia a CL95<5,0; 98 a 100 % de mortalidad); pirimifos-metil (99 a 100 % de mortalidad) y malatión (100 % de mortalidad). Conclusión. Con base en los resultados obtenidos, es factible el uso de temefos, malatión y pirimifos-metil para el control de Ae. aegypti en las poblaciones evaluadas.

Introduction. Dengue is a public health problem in La Guajira region. Control has focused on the vector using insecticides, including organophosphates. Objective. To evaluate the state of susceptibility to organophosphates insecticides in fifteen Aedes aegypti (L.) populations in La Guajira, Colombia. Materials and methods. We collected samples of third-instar larvae and adult mosquitoes of Ae. aegypti in the municipalities of Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita, Villanueva. Bioassays for temefos, malathion, and pirimiphos-methyl were carried out following the methodology of the World Health Organization, and the bottle technique using the guidance of the Centers for Disease Control and Prevention. Susceptibility to temefos was determined through the resistance ratio between lethal concentration 50 and lethal concentration 95; for the compounds temefos, malathion and pirimiphos-methyl, susceptibility was calculated using diagnostic dose and diagnostic time in the populations evaluated. Rockefeller susceptible strain was used as a control. Results. All evaluated populations of Ae. aegypti from La Guajira were found to be susceptible to temefos (ratio resistance to CL50<5.0; ratio resistance to CL95<5.0; 98 - 100 % mortality); pirimiphosmethyl (99 - 100 % mortality), and malathion (100 % mortality). Conclusion. Based on the results, the use of temefos, malathion, and pirimiphosmethyl is feasible for the control of Ae. aegypti in the evaluated populations.

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ABSTRACT Aedes albopictus is considered a potential vector of arboviruses in Colombia. Females and males naturally infected with dengue, Zika and chikungunya viruses have already been found in this country. We document the first record of Ae. albopictus in the Cordoba department, in North of Colombia. The finding was carried out during Ae. aegypti collection activities in the Ayapel, Montelibano, Planeta Rica, Pueblo Nuevo and Puerto Libertador municipalities. The entomological material was collected in water containers such as cement water tanks, tanks, bottles, tires, abandoned toilets, and plastic lids with natural water located in the intradomicile, peridomicile, and extra-domicile spaces of the homes. We collected 658 Ae. albopictus samples in the larva and pupa stages, and once these reached adulthood, we determined that 389 were female and 269 were male. This is the first record of the presence of Ae. albopictus in the Cordoba department.

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Susceptibility to organophosphates was evaluated in 2 populations of Culex quinquefasciatus from the department of Atlantico, Colombia. Bioassays for temephos, malathion, and pirimiphos-methyl were performed with 3rd-stage larvae and adult females of Cx. quinquefasciatus from the municipalities of Soledad and Puerto Colombia, following the methods of the World Health Organization and Centers for Disease Control and Prevention, respectively. The median lethal concentration (LC50) and 90% lethal concentration (LC90) resistance ratios (RRLC50 and RRLC90) were determined for each insecticide in the field populations evaluated, using the Cartagena strain as the susceptible control. Relative to LC50 and LC90 of the Cartagena strain, the population from Puerto Colombia was moderately resistant to temephos (RRLC50 5.7-fold) and malathion (RRLC50 8.6-fold, RRLC90 9-fold) and susceptible to pirimiphos-methyl (RRLC50 and RRLC90 < 5-fold). The population from Soledad was susceptible to temephos and pirimiphos-methyl (RRLC50 and RRLC90 < 5-fold) and showed moderate resistance to malathion (RRLC50 7.5-fold). It is important to emphasize that routine monitoring of insecticide resistance in Cx. quinquefasciatus helps us detect resistance early and improve the effectiveness of control strategies.

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Dengue, chikungunya, and Zika are of great concern to the public health of Colombia. One of the main control strategies for these diseases is the application of insecticides directed at the Aedes aegypti vector. However, insecticide resistance has been increasingly recorded in the country, making control measures difficult. Here, we evaluated the resistance profiles for pyrethroids in populations of Ae. aegypti from La Guajira, Colombia. The frequency (diagnostic dose, DD) and intensity (2×, 5×, and 10× DD) of resistance to permethrin, deltamethrin, and lambda-cyhalothrin were determined in 15 populations of Ae. aegypti from La Guajira, Colombia, using the bottle bioassay. The kdr mutations V1016I, F1534C, and V410L, were identified, and their allele and genotype frequencies were calculated. Finally, the mortality values for the analyzed pyrethroids were interpolated following the IDW method for predicting pyrethroid resistance. The populations of Ae. aegypti showed a high frequency of resistance to permethrin with a low to moderate intensity, which was associated with the triple-resistant haplotype LL410/II1016/CC1534. They remain susceptible to deltamethrin and, in some populations, expressed the risk of developing resistance to lambda-cyhalothrin.

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Aedes aegypti is the main vector of dengue, chikungunya, and Zika viruses, which are of great public health importance in Colombia. Aedes control strategies in Colombia rely heavily on the use of organophosphate and pyrethroid insecticides, providing constant selection pressure and the emergence of resistant populations. In recent years, insecticide use has increased due to the increased incidence of dengue and recent introductions of chikungunya and Zika. In the present study, pyrethroid resistance was studied across six populations of Ae. aegypti from the Caribbean coast of Colombia. Susceptibility to λ-cyhalothrin, deltamethrin, and permethrin was assessed, and resistance intensity was determined. Activity levels of enzymes associated with resistance were measured, and the frequencies of three kdr alleles (V1016I, F1534C, V410L) were calculated. Results showed variations in pyrethroid susceptibility across Ae. aegypti populations and altered enzyme activity levels were detected. The kdr alleles were detected in all populations, with high variations in frequencies: V1016I (frequency ranging from 0.15-0.70), F1534C (range 0.94-1.00), and V410L (range 0.05-0.72). In assays of phenotyped individuals, associations were observed between the presence of V1016I, F1534C, and V410L alleles and resistance to the evaluated pyrethroids, as well as between the VI1016/CC1534/VL410 tri-locus genotype and λ-cyhalothrin and permethrin resistance. The results of the present study contribute to the knowledge of the mechanisms underlying the resistance to key pyrethroids used to control Ae. aegypti along the Caribbean coast of Colombia.

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The use of insecticides for the control of Aedes aegypti (L.) (Diptera: Culicidae) in Colombia has indirectly influenced the susceptibility status of Culex quinquefasciatus Say populations. We evaluated pyrethroid susceptibility in two populations of Cx. quinquefasciatus in the Atlantico Department of Colombia and its possible resistance mechanism (kdr mutation). Bottle bioassays were performed for permethrin, deltamethrin, and λ-cyhalothrin in female mosquitoes of Cx. quinquefasciatus. The resistance ratios (RRs) for KC50 and LC50 for each insecticide in the field populations examined were determined, using the Cartagena strain as the susceptible control. The L1014F kdr mutation was identified in the para gene of the voltage-gated sodium channel (vgsc), along with its allelic and genotypic frequency. Low knockdown resistance (RRKC50) to deltamethrin was found in Puerto Colombia and Soledad populations as well as low resistance to λ-cyalothrin in this latter population. Moderate knockdown resistance to permethrin was found in both populations. At 24 h post-exposure on the other hand, there was low resistance (RRLC50) to permethrin in Puerto Colombia and moderate resistance in Soledad. Moderate resistance to deltamethrin was found in Puerto Colombia and low resistance in Soledad. Low resistance to λ-cyhalothrin was seen in Puerto Colombia and moderate resistance in Soledad. Variability was found in the susceptibility to the pyrethroids in the populations of Cx. quinquefasciatus evaluated, and the L1014F kdr mutation is reported for the first time as a possible pyrethroid resistance mechanism in this species in Colombia.

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Introducción: La malaria es un problema de salud pública para Colombia, con comportamiento endémico/epidémico y variación entre las diferentes áreas de transmisión. Objetivo: Describir las características epidemiológicas de pacientes con malaria, notificados por un asegurador en salud en Colombia durante los años 2016 y 2017. Métodos: Estudio descriptivo, en el que se revisó de forma retrospectiva la base de datos de todos los casos de malaria notificados por un asegurador en salud en Colombia durante los años 2016 y 2017. Se realizó un análisis descriptivo, teniendo en cuenta la naturaleza de las variables. Las variables cualitativas se analizaron a partir de las frecuencias absolutas y relativas. Se usó el test de chi cuadrado para comparar las diferencias entre proporciones, en todos los casos se estableció un valor p< 0,05 como significativo. Los datos se analizaron en el programa SPSS versión 19. Resultados: Durante el período de observación se notificaron 26 017 casos de malaria; el 50 por ciento (13 014) eran hombres y el 50 por ciento (13 003) mujeres. Los grupos etarios más afectados fueron los adultos jóvenes (26,37 por ciento), escolares (15,04 por ciento), preescolares (12,75 por ciento) y adolescentes iniciales (12,18 por ciento). La mayoría de los pacientes estudiados eran indígenas y mulatos; trabajadores no calificados, que residían y fueron notificados en el departamento del Chocó. En cuanto a las características clínicas y paraclínicas se encontró que el 95,9 por ciento de los pacientes eran sintomático, las especies parasitaria más frecuentemente fueron P. falciparum (58,86 por ciento) y P. vivax (35,95 por ciento) y en menor frecuencia P. malariae (0,06 por ciento). Se registró complicaciones en 410 pacientes, estas eran principalmente de tipo hematológicas (56,3 por ciento); sin embargo, también se registraron complicaciones cerebrales, renales, hepáticas y pulmonares. Durante los dos años se observó brotes epidémicos entre las semanas 6 a la 31, y posteriormente se observó un descenso en la notificación de casos. Conclusiones: Este estudio encontró una marcada diferencia en la incidencia de casos de malaria notificados por el asegurador objeto de estudio entre los años 2016 y 2017; la mayoría de estos casos eran por P. falciparum y se registraron en el departamento de Chocó(AU)

Introduction: Malaria is a health problem in Colombia. Its behavior is endemic / epidemic and variation is observed between the different transmission areas. Objective: Describe the epidemiological characteristics of patients with malaria notified by a health insurer in Colombia during the years 2016 and 2017. Methods: A descriptive study was conducted in which a retrospective review was performed of the database of all the malaria cases notified by a health insurer in Colombia during the years 2016 and 2017. A descriptive analysis was done taking into account the nature of the variables. Qualitative variables were analyzed in terms of absolute and relative frequencies. The chi-square test was used to compare the differences between proportions. A value of p< 0.05 was set as significant in all cases. The software SPPS version 19 was used for data analysis. Results: During the observation period a total 26 017 malaria cases were notified, of whom 50 percent were men (13 014) and 50 percent were women (13 003). The most affected age groups were young adults (26.37 percent), schoolchildren (15.04 percent), pre-schoolers (12.75 percent) and preadolescents (12.18 percent). Most of the patients studied were indigenous and mulatto, unskilled workers, and lived or were notified in the department of Chocó. With respect to clinical and paraclinical characteristics, it was found that 95.9 percent of the patients were symptomatic. The most common parasite species were P. falciparum (58.86 percent) and P. vivax (35.95 percent) and to a lesser degree P. malariae (0.06 percent). Complications were recorded in 410 patients. These were mainly hematological (56.3 percent), but brain, kidney, liver and lung complications were also found. During the two study years, epidemic outbreaks were observed between weeks 6 and 31, followed by a decrease in the number of case notifications. Conclusions: The study found a marked difference in the incidence of malaria cases notified by the study insurer between the years 2016 and 2017. Most of these cases were due to P. falciparum and were recorded in the department of Chocó(AU)

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BACKGROUND: Knockdown resistance is conferred primarily by non-synonymous mutations that reduce pyrethroids binding to voltage-gated sodium channels. In 2014, kdr mutation V1016I in Aedes aegypti populations resistant to pyrethroids was reported for the first time in Colombiα, in 2016 another kdr mutation, F1534C, and in 2018 the mutation V419L. Nine populations of A. aegypti, previously characterized as being resistant to λ-cyhalothrin, deltamethrin, cyfluthrin and permethrin, were used for this study. Genomic DNA was used to determine genotypes by allele-specific PCR for mutations V1016I and F1534C, and to determine their association with pyrethroid resistance. RESULTS: All the populations analyzed showed both mutations, with allelic frequencies of 0.07-0.35 for I1016 and 0.47-0.88 for C1534. A percentage of co-occurrence of mutant homozygotes I1016/C1534 of 5.3% was detected. A significant positive correlation was found between the frequency of the genotype I1016 and the resistance to permethrin, λ-cyhalothrin and cyfluthrin, but not to deltamethrin; on the other hand, the correlation was not significant for the C1534 genotype and the four pyrethroids evaluated. No significant correlation was found between the frequencies of the mutations V1016I and F1534C. CONCLUSIONS: Both mutations V1016I and F1534C are present in A. aegypti populations of the Colombian Caribbean, and although the frequency of F1534C exceeds V1016I, the latter was correlated to resistance to pyrethroid insecticides. © 2018 Society of Chemical Industry.

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