Changing paradigms in Aedes control: considering the spatial heterogeneity of dengue transmission / Cambio de paradigma en el control de Aedes: consideración de la heterogeneidad espacial de la transmisión del dengue

ABSTRACT Current dengue vector control strategies, focusing on reactive implementation of insecticide-based interventions in response to clinically apparent disease manifestations, tend to be inefficient, short-lived, and unsustainable within the worldwide epidemiological scenario of virus epidemic recrudescence. As a result of a series of expert meetings and deliberations, a paradigm shift is occurring and a new strategy, using risk stratification at the city level in order to concentrate proactive, sustained efforts in areas at high risk for transmission, has emerged. In this article, the authors 1) outline this targeted, proactive intervention strategy, within the context of dengue epidemiology, the dynamics of its transmission, and current Aedes control strategies, and 2) provide support from published literature for the need to empirically test its impact on dengue transmission as well as on the size of disease outbreaks. As chikungunya and Zika viruses continue to expand their range, the need for a science-based, proactive approach for control of urban Aedes spp. mosquitoes will become a central focus of integrated disease management planning.

RESUMEN Las estrategias actuales de control de vectores del dengue, centradas en la ejecución reactiva de intervenciones con insecticidas en respuesta a la aparición de cuadros clínicos evidentes de la enfermedad, suelen ser ineficientes, de duración limitada e insostenibles en el contexto epidemiológico mundial, caracterizado por la recrudescencia de las epidemias virales. Como resultado de una serie de reuniones y deliberaciones entre expertos, está en proceso un cambio de paradigma y ha surgido una nueva estrategia, que consiste en estratificar el riesgo de cada ciudad para concentrar y mantener los esfuerzos proactivos donde hay un alto riesgo de transmisión. En este artículo, los autores 1) describen esta estrategia de intervención específica y proactiva dentro del contexto de las características epidemiológicas del dengue, la dinámica de su transmisión y las estrategias actuales de control de Aedes y 2) fundamentan con fuentes bibliográficas la necesidad de demostrar empíricamente las repercusiones de esta estrategia sobre la transmisión del dengue y el tamaño de los brotes. Dado que los virus del chikunguña y el Zika siguen ampliando su alcance, uno de los objetivos primordiales de la planificación de la atención integrada de estas enfermedades estará determinado por la necesidad de adoptar un enfoque científico y proactivo del control urbano de los mosquitos del género Aedes.

Cost of intensive routine control and incremental cost of insecticide-treated curtain deployment in a setting with low Aedes aegypti infestation

Abstract: INTRODUCTION Information regarding the cost of implementing insecticide-treated curtains (ITCs) is scarce. Therefore, we evaluated the ITC implementation cost, in addition to the costs of intensive conventional routine activities of the Aedes control program in the city of Guantanamo, Cuba. METHODS A cost-analysis study was conducted from the perspective of the Aedes control program, nested in an ITC effectiveness trial, during 2009-2010. Data for this study were obtained from bookkeeping records and activity registers of the Provincial Aedes Control Programme Unit and the account records of the ITC trial. RESULTS The annual cost of the routine Aedes control program activities was US$16.80 per household (p.h). Among 3,015 households, 6,714 ITCs were distributed. The total average cost per ITC distributed was US$3.42, and 74.3% of this cost was attributed to the cost of purchasing the ITCs. The annualized costs p.h. of ITC implementation was US$3.80. The additional annualized cost for deploying ITCs represented 19% and 48.4% of the total cost of the routine Aedes control and adult-stage Aedes control programs, respectively. The trial did not lead to further reductions in the already relatively low Aedes infestation levels. CONCLUSIONS At current curtain prices, ITC deployment can hardly be considered an efficient option in Guantanamo and other comparable environments.

La inequidad en salud: el caso del dengue / Inequities in health: the casus of dengue

Las poblaciones pobres sufren una dimensión desproporcionadamente alta de la carga de enfermedad producida por las enfermedades tropicales desatendidas, dentro de ellas el dengue. La carga de enfermedad por dengue es alta entre los pobres debido a que frecuentemente viven en comunidades donde los vectores son abundantes, porque utilizan menos barreras humano-vectores y, además, por el hecho que las intervenciones suelen ser menos efectivas en estas poblaciones. Consideramos que un mejor entendimiento y manejo de “las causas detrás de las causas” del dengue conducirían a estrategias de control más equitativas y efectivas. En este artículo se desarrollan dos ideas principales: en primer lugar se propone que las intervenciones sean dirigidas a áreas geográficas bien definidas con alto riesgo de transmisión de dengue; dicha definición debería basarse en información socioeconómica, entomológica, ambiental y epidemiológica. En segundo lugar, existe la necesidad de adaptar las herramientas de control de dengue a factores específicos del contexto local, lo cual debe desarrollarse en colaboración activa con los sectores involucrados en el manejo de riesgo, así como con las comunidades afectadas.

Impoverished populations carry a disproportionately high share of the burden of neglected tropical diseases, including dengue. The burden of dengue is high among poor people because they often live in communities where mosquito vectors are abundant, because they use less vector-human barrier methods, and because interventions tend to be less effective in disadvantaged populations. We believe that a better understanding and management of the “causes behind the causes” of dengue would lead to more equitable and more effective control strategies. Two main ideas are worked out. First, we propose targeted interventions in well-defined geographical areas with high risk of dengue transmission. The definition of these high-risk areas should be based on socio-economical, entomological, environmental as well as epidemiological information. Second, there is a need to adapt dengue control tools to local, context-specific factors, in active collaboration with the sectors involved in risk management as well as with the affected communities.