Evaluación de la sensibilidad a organofosforados en poblaciones de Aedes aegypti (L. ) (Diptera: Culicidae) del departamento de La Guajira, Colombia / Evaluation of susceptibility to organophosphates in populations of Aedes aegypti (L. ) (Diptera: Culicidae) in La Guajira, Colombia

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.

Comparison of novaluron, pyriproxyfen, spinosad and temephos as larvicides against Aedes aegypti in Chiapas, Mexico / Comparación de novaluron, piriproxifeno, spinosad y temefos como larvicidas contra Aedes aegypti en Chiapas, México

Abstract: Objective: To compare the efficacy of three modern larvicides with the organophosphate temephos for control of Aedes aegypti in water tanks in Chiapas. Materials and methods: Trials were performed to compare the efficacy of pyriproxyfen, novaluron, two formulations of spinosad (granules and tablets) and temephos in oviposition traps and domestic water tanks. Results: Pyriproxyfen and temephos provided 2-3 weeks of complete control of larvae in oviposition traps, whereas spinosad granules and novaluron provided 7-12 weeks of control. Treatment of water tanks resulted in a significant reduction in oviposition by Ae. aegypt in houses (p<0.001). Higher numbers of larvae were present in temephos and pyriproxyfen-treated water tanks compared to novaluron and spinosad tablet treatments during most of the study. Conclusion: Spinosad formulations and novaluron were effective larvicides in this region. The poor performance of temephos may be indicative of reduced susceptibility in Ae. aegypti populations in Chiapas.

Resumen: Objetivo: Comparar la eficacia de tres larvicidas modernos para el control de Aedes aegypti en tanques de agua doméstica en Chiapas. Material y métodos: Se comparó la eficacia de piriproxifeno, novalurón, dos formulaciones de spinosad (gránulos y tabletas) y temefos en ovitrampas y tanques domésticos de agua. Resultados: El piriproxifeno y el temefos proporcionaron de 2 a 3 semanas de control de larvas en ovitrampas, mientras que los gránulos de spinosad y novaluron proporcionaron de 7 a12 semanas. Los tanques de agua tratados produjeron una reducción significativa en la oviposición por Ae. aegypti en las casas (p<0.001). Se encontró gran cantidad de larvas en los tanques tratados con temefos y piriproxifeno en comparación con los tratados con novaluron y tabletas de spinosad durante la mayor parte del estudio. Conclusión: Las formulaciones de spinosad en tabletas y novaluron fueron larvicidas efectivos en esta región. El bajo desempeño de temefos puede indicar una susceptibilidad reducida en poblaciones de Ae. aegypti en Chiapas.

LncRNA MALAT1/MiR-145 Adjusts IL-1β-Induced Chondrocytes Viability and Cartilage Matrix Degradation by Regulating ADAMTS5 in Human Osteoarthritis

PURPOSE: Accumulating evidence suggests that microRNA-145 (miR-145) plays an important role in osteoarthritis (OA), which is a chronic progressive joint disease. Long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promotes metastasis in cancers and functions as a sponge for miR-145. However, the role of MALAT1/miR-145 in OA pathogenesis has not yet been elucidated. MATERIALS AND METHODS: The expression of MALAT1 and miR-145 was examined by quantitative real-time PCR; the interaction between miR-145, MALAT1 and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 5 was verified by luciferase reporter assay. Correlations among MALAT1, miR-145, and ADAMTS5 were analyzed by Spearman rank analysis. Chondrocytes viability and cartilage extracellular matrix (ECM) degradation were investigated with cell viability assay and Western blotting analyzing expression of ADAMTS5, collagen type 2 alpha 1 (COL2A1), aggrecan (ACAN), and cartilage oligomeric matrix protein (COMP). RESULTS: MALAT1 was upregulated, and miR-145 was downregulated in OA samples and IL-1β-induced chondrocytes. Mechanically, miR-145 could directly bind to MALAT1 and ADAMTS5. Moreover, miR-145 expression was negatively correlated with MALAT1 and ADAMTS5 expression in OA patients, whereas MALAT1 and ADAMTS5 expression was positively correlated. Functionally, overexpression of MALAT1 inhibited chondrocyte viability and promoted cartilage ECM degradation in IL-1β-induced chondrocytes. In support thereof, MALAT1 silencing and miR-145 upregulation exerted the opposite effect in IL-1β-induced chondrocytes. Moreover, the effect of MALAT1 was counteracted by miR-145 upregulation, and ADAMTS5 restoration could abate miR-145 effects. CONCLUSION: An MALAT1/miR-145 axis contributes to ECM degradation in IL-1β-induced chondrocytes through targeting ADAMTS5, suggesting that MALAT1/miR-145/ADAMTS5 signaling may underlie human OA pathogenesis.

Resistance to temephos and deltamethrin in Aedes aegypti from Brazil between 1985 and 2017

BACKGROUND Aedes aegypti populations in Brazil have been subjected to insecticide selection pressures with variable levels and sources since 1967. Therefore, the Brazilian Ministry of Health (MoH) coordinated the activities of an Ae. aegypti insecticide resistance monitoring network (MoReNAa) from 1999 to 2012. OBJECTIVES The objective of this study was to consolidate all information available from between 1985 and 2017 regarding the resistance status and mechanisms of Brazilian Ae. aegypti populations against the main insecticide compounds used at the national level, including the larvicide temephos (an organophosphate) and the adulticide deltamethrin (a pyrethroid). METHODS Data were gathered from two sources: a bibliographic review of studies published from 1985 to 2017, and unpublished data produced by our team within the MoReNAa between 1998 and 2012. A total of 146 municipalities were included, many of which were evaluated several times, totalling 457 evaluations for temephos and 274 for deltamethrin. Insecticide resistance data from the five Brazilian regions were examined separately using annual records of both the MoH supply of insecticides to each state and the dengue incidence in each evaluated municipality. FINDINGS Ae. aegypti resistance to temephos and deltamethrin, the main larvicide and adulticide, respectively, employed against mosquitoes in Brazil for a long time, was found to be widespread in the country, although with some regional variations. Comparisons between metabolic and target-site resistance mechanisms showed that one or another of these was the main component of pesticide resistance in each studied population. MAIN CONCLUSIONS (i) A robust dataset on the assessments of the insecticide resistance of Brazilian Ae. aegypti populations performed since 1985 was made available through our study. (ii) Our findings call into question the efficacy of chemical control as the sole methodology of vector control. (iii) It is necessary to ensure that sustainable insecticide resistance monitoring is maintained as a key component of integrated vector management. (iv) Consideration of additional parameters, beyond the supply of insecticides distributed by the MoH or the diverse local dynamics of dengue incidence, is necessary to find consistent correlations with heterogeneous vector resistance profiles.

Variation in temephos resistance in field populations of Aedes aegypti (Diptera: Culicidae) in the State of Sergipe, Northeast Brazil

Abstract INTRODUCTION The organophosphate temephos was first used in Brazil in the 1960s for the control of Aedes aegypti. Because of its extensive and longstanding use worldwide, selection for mosquito populations resistant to the chemical has been observed not only in different regions of Brazil but also in several parts of the world. The objective of this study was to evaluate the susceptibility of Ae. aegypti to the organophosphate temephos, a larvicide used in vector control activities in Sergipe/Northeast Brazil. METHODS This study included mosquito populations from seven municipalities of Sergipe and was carried out from October 2010 to August 2011. Qualitative bioassays of diagnostic dose and dose responses were performed. The resistance ratio was calculated based on lethal concentrations for mosquitoes of the susceptible Rockefeller strain. RESULTS: All populations were classified as resistant to temephos. The resistance ratio ranged from 22.2 to 297.9, the lowest being seen in Aracaju, a coastal area of the state, and the highest in Pinhão, a semi-arid region, 96.6km from Aracaju. CONCLUSIONS: High levels of temephos resistance were observed in the Ae. aegypti populations of Sergipe. The variation between regions indicates that there have been different regimes of insecticide use and also points to the potential of small cities to generate and spread insecticide resistance.

Alginate-Catechol Cross-Linking Interferes with Insulin Secretion Capacity in Isolated Murine Islet Cells

Over the past three decades, human pancreatic islet isolation and transplantation techniques have developed as a routine clinical procedure for selected patients with type 1 diabetes mellitus. However, due to the donor shortage and required chronic systemic immunosuppression, the widespread application of islet transplantation is limited. To overcome these limitations, providing a physical barrier to transplanted islet cells with encapsulating biomaterial has emerged as a promising approach to enhance engraftment and promote islet survival post-transplantation. Alginate has been considered to be a reliable biomaterial, as it enhances islet survival and does not hamper hormone secretion. Alginate-catechol (Al-CA) hydrogel was reported to provide high mechanical strength and chemical stability without deformation over a wide range of pH values. In this study, we, demonstrated, for the first time in the literature, that encapsulation of murine pancreatic islet cells with Al-CA hydrogel does not induce cytotoxicity ex vivo for an extended period; however, it does markedly abate glucose-stimulated insulin secretion. Catechol should not be considered as a constituent for alginate gelation for encapsulating islet cells in the application of islet transplantation.

Control químico y biológico de larvas de Aedes aegypti en la costa norte de Jalisco, México / Chemical and biological control on Aedes aegypti larvae in the northern coastal region of Jalisco, Mexico

Introducción: el aumento de enfermedades transmitidas por mosquitos se ha asociado a cambios globales: el crecimiento de la población, la urbanización y el cambio climático. Dentro de las alternativas para evitar epidemias están el control químico y biológico. Objetivos: determinar las concentraciones efectivas de tres compuestos químicos para el control de larvas de Aedes aegypti en la región costa norte de Jalisco, México, y evaluar la capacidad predatoria de diversas especies acuáticas sobre larvas de mosquitos. Métodos: se evaluaron cinco concentraciones de temefos (1,5; 1; 0,1; 0,05 y 0,01 g/L), hipoclorito de sodio (5,5; 0,55; 0,05; 0,005 y 0,0005 g/L) y detergente (10; 5; 1; 0,5; 0,1 g/L). Se determinó la muerte de las larvas a 1, 3, 6 y 24 h y se calculó la CL50. Se evaluaron cuatro especies de peces, un crustáceo y una larva de díptero culícido. Se les suministraron diferentes cantidades de larvas (5, 10, 30, 50 y 80) por quintuplicado y se registró su consumo a diferentes tiempos (1, 3, 5, 9 y 24 h). Resultados: el temefos provocó el 100 por ciento de mortalidad en todas las concentraciones probadas. El NaClO provocó mortalidad del 100 por ciento en las dos concentraciones más altas. El detergente fue más eficiente a las tres concentraciones mayores. Los peces demostraron un consumo de casi el 100 por ciento en la mayoría de las densidades probadas. La larva de díptero culícido demostró un consumo cercano al 80 por ciento, el crustáceo solo consumió el 53 por ciento Conclusiones: el uso del temefos debe continuar siendo el larvicida químico de elección en Puerto Vallarta, México. La utilización de peces nativos se sugiere como adecuada para el control biológico(AU)

Introduction: the increase of diseases transmitted by mosquitoes has been associated to global changes such as the population growth, urbanization and climate change. Among the alternatives to avoid epidemics are the chemical and biological control. Objectives: to determine effective concentrations of three chemical compounds to control Aedes aegypti larvae in the northern coastal region of Jalisco and to evaluate the predatory ability of various aquatic species on mosquito larvae. Methods: five concentrations of temephos of (1.5, 1, 0.1; 0.05 and 0.01 g/L), sodium hypochlorite (5.5, 0.55, 0.05, 0,005 and 0.0005 g/L) and detergent (10, 5, 1, 0.5, 0.1 g/L) were evaluated. Larval death was estimated at different times (1, 3, 5, 9 and 24 h) and the LC50 was calculated. Four fish species, one crustacean and one dipteral culicid larva were evaluated. All were provided with different numbers of larvae (5, 10, 30, 50 and 80) five times and the larval consumption was recorded at different times (1, 3, 5, 9 and 24 h). Results: temephos caused 100 percent mortality of larvae in all tested concentrations. The NaClO caused 100 percent mortality at the two highest concentrations. The detergent was more efficient at the three higher concentrations. Fish proved to be efficient predators of larvae, as they consumed almost 100 percent of larvae in most of tested densities. The diptera culicid larva reached around 80 percent consumption whereas crustacean consumed only 53 percent. Conclusions: the use of temephos should remain the chemical larvicide of choice in Puerto Vallarta region. Native fish are suggested to be used as appropriate biological control agents(AU)

Perfil de susceptibilidad a temefos en poblaciones de aedes aegypti (diptera: culicidae) de ciudad del este - alto Paraná, Paraguay / Aedes aegypti (díptera-culicidae) susceptibility to temephos in ciudad del este, alto Paraná, Paraguay

En Paraguay, el control del mosquito Aedes aegypti involucrado en la transmisión de varias arbovirosis implica la utilización del Temefos, un organofosforado que ha sido utilizado por los programas nacionales para el control vectorial por más de dos décadas en busca de la reducción de los estadios larvarios. En vista de la necesidad de evaluar periódicamente la actividad larvicida del compuesto químico mencionado, este estudio tuvo como objetivo monitorear el perfil de susceptibilidad de larvas de Ae. aegypti al Temefos. Para ello se aplicó un estudio analítico experimental con ensayos biológicos tipo dosis - respuesta, utilizando larvas del tercer estadio de la primera generación procedentes de una colonia de mosquitos colectada en Ciudad del Este. Las larvas fueron expuestas a la acción del Temefos a diferentes concentraciones definidas por un pre- test. Se registraron valores correspondientes al número de larvas expuestas y mortalidad al término de cada ensayo. Los resultados fueron concentración letal CL50 = 0,00966 mg/L y CL90 = 0,03015mg/L, a partir de estos valores se obtuvieron los indicadores cuantitativos de resistencia, Razón de resistencia RR50 = 2,3734 y RR90 = 4,1643 respectivamente. Este último es un indicativo de resistencia baja en las poblaciones de Ae. aegypti evaluadas, acorde con rangos estandarizados (RR>3<5). Los resultados observados en las poblaciones silvestres de larvas revelan una situación de alerta, considerando que el presente estudio evidenció un proceso de resistencia incipiente al Temefos. Finalmente, basados en los resultados se recomienda plantear y ejecutar estrategias basadas en acciones que permitan preservar la actividad larvicida de este compuesto, evitando el aumento progresivo de resistencia en las poblaciones silvestres.

In Paraguay, the control of Aedes aegypti mosquitoes, involved in the transmission of several arboviruses, implies the use of temephos, an organophosphate that has been used by national vector control programs for more than two decades in search of reducing larval stages. In view of the need to evaluate periodically the larvicidal activity of this chemical compound, this study aimed to monitor the susceptibility profile to temephos of larval stages of Ae. aegypti. For this, an experimental analytical study with bioassays dose rate –response was applied, using third instar larva e of the first generation from a mosquitoescolony collected in Ciudad del Este. The larvae were exposed to different concentrations ranges of themephos that were defined by a pre-test. The number of larva e exposed and mortality at the end of each trial were recorded. The results determined the LC50 =0.00966 mg/L and LC90 = 0.03015 mg/L, from which quantitative indicators of resistance were obtained, resistance ratio RR = 2.3734 and 4.1643 respectively. The latter valueindicates characteristics related to low resistance in populations of Ae. aegypti evaluateda ccording to standardized ranges (RR> 3 <5). The results observed in larval wild populations indicate an alert situation, considering that our study showed an incipient process of resistance to temephos. Finally, based on these results, proposing and implementing strategies based in actions that allow to preserve the larvicidal activity of this compound are recommended to avoiding the progressive increase of resistance in wild populations.

Larvicidal activity of Syzygium aromaticum (L) Merr and Citrus sinensis (L) Osbeck essential oils and their antagonistic effects with temephos in resistant populations of Aedes aegypti

Environmentally friendly botanical larvicides are commonly considered as an alternative to synthetic larvicides against Aedes aegypti Linn. In addition, mosquito resistance to currently used larvicides has motivated research to find new compounds acting via different mechanisms of action, with the goal of controlling the spread of mosquitos. Essential oils have been widely studied for this purpose. This work aims to evaluate the larvicidal potential of Syzygium aromaticum and Citrus sinensis essential oils, either alone or in combination with temephos, on Ae. aegypti populations having different levels of organophosphate resistance. The 50% lethal concentration (LC50) of the essential oils alone and in combination with temephos and the influence of essential oils on vector oviposition were evaluated. The results revealed that essential oils exhibited similar larvicidal activity in resistant populations and susceptible populations. However, S. aromaticum and C. sinensis essential oils in combination with temephos did not decrease resistance profiles. The presence of the evaluated essential oils in oviposition sites significantly decreased the number of eggs compared to sites with tap water. Therefore, the evaluated essential oils are suitable for use in mosquito resistance management, whereas their combinations with temephos are not recommended. Additionally, repellency should be considered during formulation development to avoid mosquito deterrence.

Spatial and temporal country-wide survey of temephos resistance in Brazilian populations of Aedes aegypti

The organophosphate temephos has been the main insecticide used against larvae of the dengue and yellow fever mosquito (Aedes aegypti) in Brazil since the mid-1980s. Reports of resistance date back to 1995; however, no systematic reports of widespread temephos resistance have occurred to date. As resistance investigation is paramount for strategic decision-making by health officials, our objective here was to investigate the spatial and temporal spread of temephos resistance in Ae. aegypti in Brazil for the last 12 years using discriminating temephos concentrations and the bioassay protocols of the World Health Organization. The mortality results obtained were subjected to spatial analysis for distance interpolation using semi-variance models to generate maps that depict the spread of temephos resistance in Brazil since 1999. The problem has been expanding. Since 2002-2003, approximately half the country has exhibited mosquito populations resistant to temephos. The frequency of temephos resistance and, likely, control failures, which start when the insecticide mortality level drops below 80%, has increased even further since 2004. Few parts of Brazil are able to achieve the target 80% efficacy threshold by 2010/2011, resulting in a significant risk of control failure by temephos in most of the country. The widespread resistance to temephos in Brazilian Ae. aegypti populations greatly compromise effective mosquito control efforts using this insecticide and indicates the urgent need to identify alternative insecticides aided by the preventive elimination of potential mosquito breeding sites.

Evaluación de la resistencia a insecticidas en cepas de Aedes aegypti (Diptera: Culicidae) de la Región Caribe de Costa Rica / Evaluation of insecticide resistance in strains of Aedes aegypti (Diptera: Culicidae) from the Caribbean region of Costa Rica

Introducción: el dengue y chikungunya son virosis antroponóticas transmitidas por Aedes aegypti que afectan extensas áreas del continente americano incluyendo Costa Rica. La reciente introducción del virus Zika representa un nuevo reto para los sistemas de salud. Dada la ausencia de tratamiento antiviral y vacunas, el control del vector Ae. aegypti, representa la única alternativa para minimizar el impacto de estas virosis. En Costa Rica, el control químico del vector se hace mediante la aplicación de piretroides (cipermetrina y deltametrina) y del organofosforado temefós; de ahí la importancia de detectar la aparición de resistencia a estos insecticidas. Objetivo: determinar el nivel de resistencia a temefós, cipermetrina y deltametrina en tres cepas de Ae. aegypti de la Región Caribe de Costa Rica, así como los mecanismos de detoxificación enzimática correspondientes. Métodos: la resistencia a temefós, cipermetrina y deltametrina se evaluó mediante bioensayos larvarios. Grupos de 20 larvas se expusieron por 24 h a 5 concentraciones de insecticidas que generaron una mortalidad entre el 2 y el 100 por ciento. Cada concentración se evaluó mediante cinco réplicas y se calculó la concentración que causa el 50 por ciento de letalidad (CL50). Como control susceptible se empleó la cepa Rockefeller. Con cada cepa se calculó un factor de resistencia 50 por ciento (FR50) para cada insecticida. Cuando se observó resistencia, se repitieron los bioensayos mediante exposición previa de las larvas a butóxido de piperonilo (PB) y S,S,S, tributilfosforotritioato (DEF) para evaluar el mecanismo detoxificante relacionado. Resultados: ninguna de las cepas evaluadas fue resistente al temefós. En las cepas Guápiles y Limón se determinó una resistencia incipiente a cipermetrina (CL50= 0,01022, FR50= 7,35 y CL 50= 0,01016, FR50= 7,30, respectivamente), mientras que en la cepa Siquirres se detectó resistencia a deltametrina (CL50= 0,01973 mg/L, FR5= 12,64). En los casos referidos hubo una disminución de la resistencia cuando se dio el pretratamiento con PB, lo que indica una detoxificación mediada por el sistema Cit P450 monooxigenasa. Conclusiones: los resultados en el presente estudio demuestran que el temefós sigue siendo efectivo para el control larvario de Ae. aegypti en las principales localidades de la región Caribe de Costa Rica. Con respecto a los piretroides se alerta ante la aparición de resistencia, lo que conlleva la necesidad de optimizar los procesos de monitoreo y la implementación de otras alternativas de control químico(AU)

Introduction: dengue and chikungunya are anthroponotic virus infections transmitted by Aedes aegypti mosquitoes. These conditions affect large areas of the American continent, including Costa Rica. The recent introduction of Zika virus infection is a new challenge for health systems. Given the absence of antiviral treatment and vaccines, Aedes aegypti control is the only alternative to minimize the impact of these viral diseases. In Costa Rica chemical control of the vector is based on the use of pyrethroids (cypermethrin and deltamethrin) and the organophosphate larvicide temephos, hence the importance of detecting the emergence of resistance to these insecticides. Objective: determine the level of resistance to temephos, cypermethrin and deltamethrin in three Aedes aegypti strains from the Caribbean region of Costa Rica, as well as the corresponding enzymatic detoxification mechanisms. Methods: resistance to temephos, cypermethrin and deltamethrin was evaluated with larval bioassays. Groups of 20 larvae were exposed to 5 insecticide concentrations for 24 h. Mortality ranged between 2 and 100 percent. Each concentration was evaluated by means of five replications, and estimation was performed of the concentration causing 50 percent lethality (CL50). The Rockefeller strain was used as susceptible control. Each strain underwent estimation of a 50 percent resistance factor (RF50) for each insecticide. Whenever resistance was observed, the bioaasays were repeated with prior exposure of the larvae to piperonyl butoxide (PBO) and S.S.S. phosphotrithiate tributyl (DEF) to evaluate the corresponding detoxification mechanism. Results: none of the strains evaluated was resistant to temephos. Incipient resistance to cypermethrin was detected in strains Guápiles and Limón (CL50= 0.01022, RF50= 7.35 and CL 50= 0.01016, RF50= 7.30, respectively), whereas resistance to deltamethrin was detected in the Siquirres strain (CL50= 0.01973 mg/L, RF50= 12.64). In the above-mentioned cases resistance decreased when pre-treatment with PBO was provided, indicating the presence of detoxification mediated by the Cyt P450 monooxygenase system. Conclusions: results show that temephos continues to be effective for larval control of Aedes aegypti in the main areas of the Caribbean region of Costa Rica. A warning is hereby given about the emergence of pyrethroid resistance, leading to the need to optimize monitoring processes and the implementation of other chemical control alternatives(AU)

Current epidemiological situation of Middle East respiratory syndrome coronavirus clusters and implications for public health response in South Korea

Since May 20, 2015, when the first case of Middle East respiratory syndrome (MERS) in South Korea was confirmed, the cluster case in South Korea has grown to become the largest observed case following Saudi Arabia within the span of one month. Akin to what was observed in the Middle East, confirmed cases were infected through nosocomial transmission where the cluster is largely limited to patients, healthcare workers, and visitors to patients in healthcare facilities with confirmed cases. A major difference from the outbreaks in the Arabian Peninsula has been the large number of tertiary transmission cases in South Korea, which had reached forty cases by June 12. This observation may suggest that despite the lack of genetic mutation of Middle East respiratory syndrome coronavirus (MERS-CoV) in South Korea, the virus may be behaving differently from that of the Middle East. The higher infectiousness of 'super-spreaders' in South Korea also suggests that this assertion should be under further investigation. Suggestions of inadequate triage in emergency rooms, particularly at Samsung Medical Center which accounts for the most nosocomial infection with 60 cases, have been made by several organizations as the basis for this rapid spread. This, however, does not account for the fact that triage was impossible to implement, since the presence of MERS-CoV in South Korea was unknown during the index patient's stay at the healthcare facilities. This paper aims to identify the key factors in the amplified spread of MERS-CoV in South Korea. The first is the initial failure to confirm diagnosis promptly and to isolate the index case after confirmation of MERS in hospital and the lack of detail in tracking potential exposures in the community of the index case before isolation. The second is the early inadequate measures the Korea Centers for Disease Control and Prevention took in categorizing close contacts. Due to inconsistencies in defining what constitutes close contact, a number of cases were neglected from quarantine and were not subjected to investigation. Finally, confirmed or potential MERS patients were admitted for treatment and observation at medical facilities without adequate disease control measures or rooms, such as ventilated single rooms or airborne precaution rooms. Due to the rigid position that MERS-CoV cannot be transmitted via airborne means, infection control measures has so far neglected evidence that smaller droplets (aerosol) containing the virus can act similar to airborne agents, which may account for the widespread and rapid transmission in a emergency room and a patient's room in hospital. Although the South Korean government expects newly confirmed cases to abate in the coming few weeks, without stringent implementation of clearly defined guidelines to control further transmissions, the cessation of the current trend may continue for an extended period. Additionally, due to the high infection rate of super-spreaders in South Korea, efforts to screen for potential super-spreaders and a thorough investigation of those confirmed to be super-spreaders should be done to quickly identify source of infection, to potentially lower the number of secondary, tertiary transmissions and prevent possible quaternary transmissions.

Evaluation of the role of ATP-binding cassette transporters as a defence mechanism against temephos in populations of Aedes aegypti

The role of ATP-binding cassette (ABC) transporters in the efflux of the insecticide, temephos, was assessed in the larvae of Aedes aegypti. Bioassays were conducted using mosquito populations that were either susceptible or resistant to temephos by exposure to insecticide alone or in combination with sublethal doses of the ABC transporter inhibitor, verapamil (30, 35 and 40 μM). The best result in the series was obtained with the addition of verapamil (40 μM), which led to a 2x increase in the toxicity of temephos, suggesting that ABC transporters may be partially involved in conferring resistance to the populations evaluated.

Resistance of Aedes aegypti to temephos and adaptive disadvantages / Resistência de Aedes aegypti ao temefós e desvantagens adaptativas

OBJECTIVE To evaluate the resistance of Aedes aegypti to temephos Fersol 1G (temephos 1% w/w) associated with the adaptive disadvantage of insect populations in the absence of selection pressure. METHODS A diagnostic dose of 0.28 mg a.i./L and doses between 0.28 mg a.i./L and 1.40 mg a.i./L were used. Vector populations collected between 2007 and 2008 in the city of Campina Grande, state of Paraíba, were evaluated. To evaluate competition in the absence of selection pressure, insect populations with initial frequencies of 20.0%, 40.0%, 60.0%, and 80.0% resistant individuals were produced and subjected to the diagnostic dose for two months. Evaluation of the development of aquatic and adult stages allowed comparison of the life cycles in susceptible and resistant populations and construction of fertility life tables. RESULTS No mortality was observed in Ae. aegypti populations subjected to the diagnostic dose of 0.28 mg a.i./L. The decreased mortality observed in populations containing 20.0%, 40.0%, 60.0%, and 80.0% resistant insects indicates that temephos resistance is unstable in the absence of selection pressure. A comparison of the life cycles indicated differences in the duration and viability of the larval phase, but no differences were observed in embryo development, sex ratio, adult longevity, and number of eggs per female. CONCLUSIONS The fertility life table results indicated that some populations had reproductive disadvantages compared with the susceptible population in the absence of selection pressure, indicating the presence of a fitness cost in populations resistant to temephos. .

OBJETIVO Avaliar a resistência de Aedes aegypti ao temefós Fersol 1G (temefós 1% p/p) quanto à desvantagem adaptativa ao inseto, na ausência de pressão de seleção. MÉTODOS Foi aplicada a dose diagnóstica de 0,28 mg i.a/L e concentrações entre 0,28 mg i.a/L e 1,4 mg i.a/L. Foram avaliadas amostras do vetor coletadas no município de Campina Grande entre 2007 e 2008, no estado da Paraíba. Para avaliar a competição na ausência de pressão de seleção, foram constituídos grupos de insetos com frequências iniciais de 20,0%, 40,0%, 60,0% e 80,0% de insetos resistentes, submetendo-os a dose diagnóstica por dois meses. Os ciclos de vida das populações suscetível e resistentes foram comparados avaliando-se as fases de desenvolvimento aquática e adulta, construindo-se tabelas de vida de fertilidade. RESULTADOS Não foram verificadas mortalidades nas populações de Ae. aegypti quando submetidas à dose diagnóstica de 0,28 mg i.a./L. A diminuição da mortalidade nas populações com 20,0%, 40,0%, 60,0% e 80,0% de indivíduos resistentes indica que a resistência ao temefós é instável na ausência de pressão de seleção. A comparação do ciclo de vida mostrou diferenças na duração da fase e viabilidade larval, mas não quanto ao desenvolvimento embrionário, razão sexual, longevidade dos adultos e número de ovos/fêmea. CONCLUSÕES Pelos parâmetros da tabela de vida de fertilidade constatou-se que algumas populações apresentaram desvantagens reprodutivas em relação à população suscetível na ausência de pressão de seleção, havendo custo adaptativo resultante da resistência ao temefós. .

Effects of piperonyl butoxide on the toxicity of the organophosphate temephos and the role of esterases in the insecticide resistance of Aedes aegypti

Introduction The effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated. Methods A. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined. Results At concentrations of 0.25, 0.5, 1, and 2%, PBO showed a significant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only. Conclusions The results of the biochemical assays suggest that PBO has a significant inhibitory effect on the total esterase activity in A. aegypti larvae. .

Evaluación de temefos y pyriproxifeno en aedes aegypti (Diptera: Culicidae) de Guayaquil, Ecuador / Evaluation of temephos and pyriproxifen against aedes aegypti (Diptera: Culicidae) from Guayaquil, Ecuador

Introducción: el Ministerio de Salud Pública de la ciudad de Guayaquil, Ecuador, ha utilizado, hasta la fecha, temefos (abate) como principal medida química para el control larval de Aedes aegypti, principal vector del dengue en este país.Objetivos: determinar la resistencia a temefos y sus mecanismos bioquímicos en dos cepas Aedes aegypti de Ecuador, así como determinar la eficacia del regulador de crecimiento, pyriproxifeno, como posible alternativa para su control.Métodos: en larvas de Aedes aegypti provenientes de dos localidades (Pascuales y Guayacanes), de la ciudad de Guayaquil, Ecuador, se evaluó la resistencia al insecticida oganofosforado temefos y la eficacia del pyriproxifeno mediante metodologías recomendadas por la Organización Mundial de la Salud. Los mecanismos de resistencia metabólicos se determinaron a través de ensayos bioquímicos y electroforesis en gel de poliacrilamida.Resultados: las larvas de la cepa Pascuales resultaron con moderado nivel de resistencia a temefos y Guayacanes resultó susceptible. A través de ensayos bioquímicos y electroforesis se demostró que el mecanismo de resistencia de acción metabólica, basado en una incrementada actividad de la esterasa-A4, resultó ser responsable de la resistencia detectada a temefos. Las dosis de pyriproxifeno que causaron 50 por ciento de inhibición de la emergencia (IE50) y 95 por ciento (IE95), resultaron muy similares entre las cepas de Ecuador y la cepa de referencia susceptible a insecticidas, Rockefeller.Conclusiones: se demostró que el mecanismo de esterasas, responsable de la resistencia a temefos, está presente en Aedes aegypti de Guayaquil, Ecuador, de ahí la necesidad de monitorear este fenómeno en diferentes regiones del país. El regulador de crecimiento pyriproxifeno resultó muy eficaz, y esto lo convierte en una alternativa a evaluar para el control de poblaciones de Aedes aegypti en Ecuador.

Introduction: the Ministry of Public Health in the city of Guayaquil, Ecuador, has so far used temephos (abate) as the main chemical measure for larval control of Aedes aegypti, the fundamental dengue vector in the country. Objectives: determine temephos resistance and its biochemical mechanisms in two strains of Aedes aegypti in Ecuador, and determine the efficacy of the growth regulator pyriproxyfen as a possible control alternative. Methods: resistance to organophosphorus insecticide temephos and the efficacy of pyriproxyfen were evaluated in Aedes aegypti larvae from two areas (Pascuales and Guayacanes) in the city of Guayaquil, Ecuador, by means of methodologies recommended by the World Health Organization. Metabolic resistance mechanisms were determined by biochemical assays and polyacrylamide gel electrophoresis. Results: larvae from the Pascuales strain showed moderate resistance to temephos, whereas those from the Guayacanes strain were found to be susceptible. Biochemical assays and electrophoresis revealed that the resistance mechanism of metabolic action, based on increased esterase-A4 activity, was responsible for the temephos resistance observed. The doses of pyriproxyfen causing 50 percent emergence inhibition (EI50) and 95 percent (EI95) were very similar between strains from Ecuador and the reference insecticide susceptible strain Rockefeller. Conclusions: it was found that the esterase mechanism, responsible for temephos resistance, is present in Aedes aegypti from Guayaquil, Ecuador. Hence the need to monitor this phenomenon in different regions of the country. The growth regulator pyriproxyfen proved to be very effective, which turns it into an alternative to evaluate for the control of Aedes aegypti populations in Ecuador.

Custo biológico associado à resistência ao inseticida temephos em populações de Aedes aegypti (DIPTERA: CULICIDAE) / Fitness cost associated with resistance to insecticide temephos in Aedes aegypti populations (DIPTERA: CULICIDAE)

Este estudo avaliou o desempenho biológico e reprodutivo de populações de Aedes aegypti resistentes ao organofosforado temephos, através da análise dos seguintes parâmetros: dinâmica de desenvolvimento de formas imaturas (larvas, pupas) e adultas; tamanho; fecundidade; tabela de vida de fertilidade; longevidade e reservas energéticas. Os testes foram realizados com uma população de campo (Arcoverde/PE), com elevada razão de resistência ao inseticida (RR=226,6), além de três linhagens isogenéticas, RecR (RR=303,4), RecRNEx (RR=250,5) em processo de reversão da resistência e RecRev (RR=2,32), susceptível revertida, usada como controle nos experimentos. Os resultados revelaram que a ausência de exposição ao temephos levou a redução da RR da RecRNex e a recuperação do padrão de normalidade de algumas enzimas, exceto a-esterase e GST, principais responsáveis pela resistência metabólica. Parâmetros biológicos foram comprometidos nas populações resistentes, sobretudo o tempo de desenvolvimento larval, o número de fêmeas reprodutivamente ativas e a fecundidade. A análise da tabela de vida de fertilidade confirmou desvantagens para as populações resistentes ligadas a redução nos valores da taxa líquida de reprodução, tempo geracional, capacidade inata de aumentar em número, razão finita de aumento e tempo necessário para duplicação do número de indivíduos. A longevidade também foi menor para as fêmeas resistentes, variando de 16,5 a 24,5 dias comparada a 38,9 dias para as susceptíveis. O tamanho, inferido pela morfometria alar e pelo peso úmido, bem como as reservas lipídicas, mostraram valores similares entre a RecRev e Arcoverde, e diferentes das linhagens RecRNex e RecR. A interpretação dos 20 parâmetros avaliados revelou que 13 deles estavam alterados para a RecR e a RecRNex e 12 para Arcoverde. Os resultados sugerem a existência de um elevado custo adaptativo associado à manutenção do mecanismo de resistência metabólica ao temephos nas populações investigadas.

Perfil de suscetibilidade da população de Aedes aegypti (Diptera: Culicidae) da ilha de Santiago, Cabo Verde, a inseticidas / Susceptibility profile of Aedes aegypti from Santiago Island, Cape Verde, to insecticides

Em Cabo Verde, arquipélago situado na Costa Ocidental Africana, os primeiros casos de dengue ocorreram em 2009, com a notificação de mais de 21.000 casos, a maioria desses registrados na Ilha de Santiago. O mosquito Aedes aegypti foi identificado como vetor, e ações para seu controle, usando os inseticidas temephos (larvicida) e a deltametrina (adulticida), têm sido implementadas. Objetiva-se com esse trabalho avaliar o atual status de suscetibilidade a inseticidas e caracterizar os mecanismos de resistência nessa população. Amostras de A. aegypti da ilha de Santiago foram coletadas através de armadilhas de oviposição, para o estabelecimento de uma população a ser analisada. Foram realizados bioensaios do tipo dose diagnóstica, usando garrafas impregnadas com doses únicas dos adulticidas malathion (organofosforado), deltametrina (piretróide) e cipermetrina (piretróide), e bioensaios do tipo dose resposta, usando múltiplas concentrações dos inseticidas temephos (organofosforado), Bacillus thuringiensis sorovariedade israelensis (bactéria entomopatogênica) e diflubenzuron (inibidor de síntese de quitina). Para a investigação dos mecanismos de resistências, foram realizados testes bioquímicos com substratos específicos para quantificar a atividade das enzimas glutationa S-transferases, esterases (alfa, beta e PNPA) e oxidases de função mista, ligadas a detoxificação de xenobióticos, e a taxa de inibição da acetilcolinesterase ligada a insensibilidade do sítio alvo...

Cape Verde, an archipelago located on the West African Coast, recorded the first cases of dengue in 2009 in an epidemic with more than 21,000 reportedcases. The worst affected area was Santiago Island...