Culicidae assemblages of artificial containers and possible biotic interactions affecting Aedes albopictus (Diptera: Culicidae) in Argentina.

In Argentina, the distribution of Aedes albopictus (Skuse) is limited to two provinces with a subtropical climate and few records. This study aims to describe and compare assemblies of Culicidae that breed in artificial containers in two areas with different degrees of urbanisation where Ae. albopictus is present and to evaluate possible biotic interactions. We sampled container larval habitats of an urban (Eldorado city) and a rural environment (Colonia Aurora village). We performed generalized linear mixed models to evaluate which variables (containers characteristics or environment) are associated with the presence and abundance of Ae. albopictus, Aedes aegypti Linneaus and Culex quinquefasciatus Say, and the presence of mosquito predators (Lutzia bigoti (Bellardi) and Toxorhynchites spp.). Also, the relationship between the most abundant species was quantified in each environment using Hurlbert's C8 association coefficient. Ae. aegypti was the most abundant species in the urban environment, while Cx. quinquefasciatus and Ae. albopictus were the most abundant in the rural area. Predators were more present in the rural environment and affected the abundance of Aedes mosquitoes. Regarding the C8 index, Ae. aegypti was negatively associated with Ae. albopictus in the urban area, whereas in the rural area these species presented a significantly positive relationship. These results show that in urban environments the high abundance of Ae. aegypti could be affecting the Asian tiger mosquito as evidenced by local studies of food larval competition. Also a greater presence of predators could be affecting Ae. albopictus in rural environments.

Larval Competition Between Aedes albopictus and Aedes aegypti (Diptera: Culicidae) in Argentina: Coexistence and Implications in the Distribution of the Asian Tiger Mosquito.

Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) are worldwide vectors of dengue and yellow fever viruses. These species coexist in many countries and the biotic interactions between them can influence their abundances and distributions. In Argentina, Ae. aegypti is widely distributed in the north and center regions of the country, with temperate and subtropical climate, while both are sympatric only in the northeastern area of the subtropical region. Interspecific and intraspecific larval competition for food was evaluated to assess if their interaction influences on patterns of abundance and distribution. Finite rates of increase and survivorship for each species were estimated and the effects of mosquito density ratio and detritus availability were determined. The Lambda (λ´) index of population performance of both showed there is no competitive exclusion pattern. However, survival of Ae. albopictus was negatively affected by the presence of Ae. aegypti. These results suggest one possible explanation for the codominance pattern of both species display in rural regions of the southernmost distribution of Ae. albopictus in South America. They also show Ae. aegypti as a potential biotic barrier for the expansion of Ae. albopictus as was reported in regions of the United States.

Descripción del Primer Brote de Dengue en la Ciudad de Santo Tomé, Corrientes, 2016 / Description of the First Dengue Outbreak in the City of Santo Tomé, Corrientes, 2016

Argentina sufrió diferentes brotes de dengue en las regiones más cálidas durante el verano de 2016. En la ciudad de Santo Tomé (Corrientes) se produjo el primer brote. En este marco, el objetivo del trabajo fue evaluar la distribución temporal y espacial de los casos de dengue en Santo Tomé, así como las acciones adoptadas para interrumpir la transmisión. MÉTODOS: Los casos sospechosos fueron detectados por el personal sanitario, se confirmaron las muestras por análisis serológico y se georreferenció cada caso positivo, que fue clasificado como autóctono o importado. Las acciones de prevención fueron: bloqueo larval; control focal y rociado espacial; evaluación de larvicidas; descacharrado; charlas, capacitaciones y asamblea barrial. RESULTADOS: De 148 pacientes sospechosos se confirmaron 52 entre las semanas epidemiológicas 3 y 22. La cepa circulante fue DENV 1. El 46% (24/52) de los casos fueron autóctonos y se concentraron en el barrio Sarmiento. El 21% (140/655) de las viviendas presentaron criaderos de culícidos, de los cuales el 84% (210/251) resultó positivo para Ae. aegypti. DISCUSIÓN: Santo Tomé tuvo todas las condiciones para que se registrara el brote de dengue: población susceptible, presencia del vector y arribo de casos importados. Si bien la distribución de casos fue homogénea durante todo el brote, en el barrio Sarmiento se vio una clara circulación viral, que pudo ser controlada mediante una tarea interdisciplinaria de acción y prevención

Update on the distribution of Aedes albopictus (Diptera: Culicidae) in Misiones, Argentina.

The Asian tiger mosquito ( Aedes albopictus, Diptera: Culicidae) has spread rapidly in the last 30 years from its native region in Southeast Asia. In Argentina, studies on its potential distribution suggest that this species could be found in temperate zones of the province of Buenos Aires. However, since its initial detection in 1998 Ae. albopictus is bounded to the subtropical province of Misiones. To evaluate the presence and abundance of Ae. albopictus in the Northeast of Argentina, we preliminarily evaluated the presence of this vector by analyzing its presence in tires of 20 cities belonging to the province of Misiones and four cities in Northern Corrientes, and then performed an evaluation of the vector in the towns where the vector was detected. Aedes albopictus was present only in two cities of Misiones: Eldorado and Colonia Aurora. Aedes aegypti and Ae . albopictus accounted for 86% of the individuals collected in the domiciles of both towns. In Colonia Aurora both species were in similar abundances suggesting a co-dominance. The present study extends the austral distribution of Ae. albopictus in Argentina to the city of Colonia Aurora where the highest abundance recorded in Argentina was detected. Nevertheless, the reasons of its bounded distribution in the region are not known.

Is autumn the key for dengue epidemics in non endemic regions? The case of Argentina.

BACKGROUND: Dengue is a major and rapidly increasing public health problem. In Argentina, the southern extreme of its distribution in the Americas, epidemic transmission takes place during the warm season. Since its re-emergence in 1998 two major outbreaks have occurred, the biggest during 2016. To identify the environmental factors that trigger epidemic events, we analyzed the occurrence and magnitude of dengue outbreaks in time and space at different scales in association with climatic, geographic and demographic variables and number of cases in endemic neighboring countries. METHODS: Information on dengue cases was obtained from dengue notifications reported in the National Health Surveillance System. The resulting database was analyzed by Generalized Linear Mixed Models (GLMM) under three methodological approaches to: identify in which years the most important outbreaks occurred in association with environmental variables and propose a risk estimation for future epidemics (temporal approach); characterize which variables explain the occurrence of local outbreaks through time (spatio-temporal approach); and select the environmental drivers of the geographical distribution of dengue positive districts during 2016 (spatial approach). RESULTS: Within the temporal approach, the number of dengue cases country-wide between 2009 and 2016 was positively associated with the number of dengue cases in bordering endemic countries and negatively with the days necessary for transmission (DNT) during the previous autumn in the central region of the country. Annual epidemic intensity in the period between 1999-2016 was associated with DNT during previous autumn and winter. Regarding the spatio-temporal approach, dengue cases within a district were also associated with mild conditions in the previous autumn along with the number of dengue cases in neighboring countries. As for the spatial approach, the best model for the occurrence of two or more dengue cases per district included autumn minimum temperature and human population as fixed factors, and the province as a grouping variable. Explanatory power of all models was high, in the range 57-95%. DISCUSSION: Given the epidemic nature of dengue in Argentina, virus pressure from endemic neighboring countries along with climatic conditions are crucial to explain disease dynamics. In the three methodological approaches, temperature conditions during autumn were best associated with dengue patterns. We propose that mild autumns represent an advantage for mosquito vector populations and that, in temperate regions, this advantage manifests as a larger egg bank from which the adult population will re-emerge in spring. This may constitute a valuable anticipating tool for high transmission risk events.

Condiciones y ambiente de trabajo en dos centros de acopio de materiales reciclables del Area Metropolitana de Buenos Aires / Conditions and Environment of Work in Two Recycling Centers in the Metropolitan Area of Buenos Aires

INTRODUCCIÓN: Las plantas de clasificación de residuos aparecen como una alternativa de inserción para los cartoneros. No obstante, se advierten falencias que producen efectos perjudiciales sobre la salud y el ambiente laboral de estos trabajadores no clásicos. OBJETIVOS: Describir el proceso, las condiciones y el medio ambiente de trabajo en centros de acopio y separación de reciclables en el Área Metropolitana de Buenos Aires (AMBA), evaluando las exigencias físicas y el riesgo sanitario. MÉTODOS: Se realizó un estudio descriptivo en dos establecimientos del AMBA, uno en contexto urbano y el otro en descampado periurbano. Se efectuó trabajo de campo etnográfico con observación, entrevistas y dinámicas grupales con técnicas proyectivas y eutonía, en paralelo con muestreos biológicos. RESULTADOS: Se identificaron situaciones externas de riesgo y otras propias del trabajador definidas como exigencias. No se encontraron virus, aunque sí vectores de dengue y encefalitis San Luis. Existe circulación de parásitos con reservorio en roedores, perros y gatos. Se documentaron otros riesgos asociados a residuos industriales, deficiente provisión de agua e incendio. Se registró sobrecarga sobre los trabajadores varones. CONCLUSIONES: Se sugiere vigilancia sanitaria en perros, gatos, roedores e insectos, así como muestreo aleatorio de materiales ingresados. Para reducir exigencias se indica rotación entre puestos y uso de máquinas simples.

INTRODUCTION: Recycling centers appear as an alternative for the employability of informal garbage collectors. However, there are deficiencies producing harmful effects on human health and the labor environment of these non-conventional workers. OBJECTIVES: To describe the process, conditions and environment of work of recycling centers in the Metropolitan Area of Buenos Aires (MABA), evaluating physical demands and health risk. METHODS: A descriptive study was conducted in two recycling facilities located in the MABA, one in an urban setting and the other one in a peri-urban area. Ethnographic fieldwork was carried out with observation, interviews and group dynamics with projective techniques and eutony, in parallel with biological sampling. RESULTS: External risk situations were identified, along with other worker-related factors defined as demands. No viruses were found, although there are vectors of dengue and Saint Louis encephalitis. There is also circulation of parasites with reservoir in rodents, dogs and cats. Other risks associated with industrial waste, poor water supply and fire were documented. There was an overload on male workers. CONCLUSIONS: Sanitary surveillance is suggested in dogs, cats, rodents and insects, as well as random sampling of incoming materials. Job rotation and use of simple machines are indicated to reduce demands.

Evaluación de insecticida en terreno para el control del vector del dengue / Evaluation of an insecticide in the field for the control of the dengue vector

INTRODUCCIÓN Las enfermedades transmitidas por insectos vectores, como el dengue y la enfermedad de Chagas, registran cada año miles de defunciones. El control de las poblaciones de los vectores es la principal herramienta para prevenir estas enfermedades. En este marco, existen protocolos para la evaluación de insecticidas en terreno que no se adaptan a las diversas realidades sociales, climáticas y ambientales que presenta nuestro país. OBJETIVO Se proponen dos objetivos; 1) Diseñar protocolos de evaluación de insecticidas en terreno para el control de los vectores del dengue y la enfermedad de Chagas con adaptaciones a la heterogeneidad de la región; y 2) evaluar la eficacia en terreno de un insecticida con efecto larvicida y adulticida para el control de las poblaciones de Ae. aegypti. METODOS Se diseñaron protocolos para la evaluación de insecticidas contra las poblaciones de Ae. aegypti y T. infestans. Además, se evaluó el efecto larvicida y adulticida de un producto contra Ae. aegypti en Santo Tomé (Corrientes). Para ello se estimó la supervivencia de adultos, mortalidad de estadios preimaginales, porcentaje de emergencia e indicadores entomológicos de la población local de forma semanal en viviendas de dos áreas de la ciudad. En una se aplicó el producto mediante máquina UBV y la otra fue considerada como control. RESULTADOS Se generaron dos protocolos para la evaluación de insecticidas en terreno; uno para Ae. aegypti y otro para T. infestans. En la evaluación sobre Ae. aegypti, se observó un incremento del 24,06% de mortalidad total de los estados preimaginales y una disminución del 29,32% de la emergencia de los adultos. Solo la cantidad de adultos y el índice de Breteau de los índices entomológicos presentaron una merma en las semanas posteriores al tratamiento. DISCUSIÓN El producto evaluado mostró una elevada eficacia. Sin embargo un incremento de los índices en la semanas subsiguientes al tratamiento sugieren la implementación de técnicas de control adicionales en el tiempo

Condiciones y ambiente de trabajo en dos centros de acopio de materiales reciclables del Area Metropolitana de Buenos Aires / Conditions and Environment of Work in Two Recycling Centers in the Metropolitan Area of Buenos Aires

INTRODUCCIÓN: Las plantas de clasificación de residuos aparecen como una alternativa de inserción para los cartoneros. No obstante, se advierten falencias que producen efectos perjudiciales sobre la salud y el ambiente laboral de estos trabajadores no clásicos. OBJETIVOS: Describir el proceso, las condiciones y el medio ambiente de trabajo en centros de acopio y separación de reciclables en el Área Metropolitana de Buenos Aires (AMBA), evaluando las exigencias físicas y el riesgo sanitario. MÉTODOS: Se realizó un estudio descriptivo en dos establecimientos del AMBA, uno en contexto urbano y el otro en descampado periurbano. Se efectuó trabajo de campo etnográfico con observación, entrevistas y dinámicas grupales con técnicas proyectivas y eutonía, en paralelo con muestreos biológicos. RESULTADOS: Se identificaron situaciones externas de riesgo y otras propias del trabajador definidas como exigencias. No se encontraron virus, aunque sí vectores de dengue y encefalitis San Luis. Existe circulación de parásitos con reservorio en roedores, perros y gatos. Se documentaron otros riesgos asociados a residuos industriales, deficiente provisión de agua e incendio. Se registró sobrecarga sobre los trabajadores varones. CONCLUSIONES: Se sugiere vigilancia sanitaria en perros, gatos, roedores e insectos, así como muestreo aleatorio de materiales ingresados. Para reducir exigencias se indica rotación entre puestos y uso de máquinas simples