Factors Affecting Infestation by Triatoma infestans in a Rural Area of the Humid Chaco in Argentina: A Multi-Model Inference Approach

Vector-borne transmission of Chagas disease remains a major public health problem in parts of Latin America. Triatoma infestans is the main vector in the countries located in the South American Cone, particularly in the Gran Chaco ecoregion where residual insecticide control has achieved only a moderate, irregular impact. To contribute to improved control strategies, we analyzed the factors associated with the presence and abundance of T. infestans in 327 inhabited houses in a well-defined rural area with no recent vector control interventions in the humid Argentine Chaco. Bugs were found mainly in domiciles, kitchens, storerooms, and chicken coops and nests, particularly where adequate refuge and animal hosts (humans, dogs, cats or poultry) were available. Domiciles constructed from mud were the most often infested, but brick-and-cement domiciles, even in good conditions, were also found infested. Availability of refuge and hosts for T. infestans are key targets for vector control. Ten-fold variations in domestic infestation observed across neighboring villages, and differences in the relevant factors for T. infestans presence with respect to other areas of the Gran Chaco region suggest that host management, building techniques and insecticide use need to be tailored to the local environment, socio-economic characteristics, and climatic conditions

Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan peninsula, Mexico

Background Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. Methodology/principal findings We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. Conclusions/significance These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control

Spatial Re-Establishment Dynamics of Local Populations of Vectors of Chagas Disease

Chagas disease is transmitted by blood-sucking bugs (vectors) and presents a severe public health threat in the Americas. Worldwide there are approximately 10 million people infected with Chagas disease, a disease for which there is currently no effective cure. Vector suppression is the main strategy to control the spread of this disease. Unfortunately, the vectors have been resurgent in some areas. It is important to understand the dynamics of reinfestation where it occurs. Here we show how different models fitted to patch-level bug infestation data can elucidate different aspects of re-establishment dynamics. Our results demonstrated a 6-month time lag between detection of a new infestation and dispersal events, seasonality in dispersal rates and effects of previous vector infestation on subsequent vector establishment rates. In addition we provide estimates of dispersal distances and the effect of insecticide spraying on rates of vector re-establishment. While some of our results confirm previous findings, the effects of season and previous infestation on bug establishment challenge our current understanding of T. infestans ecology and highlight important gaps in our knowledge of T. infestans dispersal

Biological control in Argentina: state of the art

El control biológico (CB) puede suceder en forma natural (sin intervención humana), oaplicado cuando es resultado del estudio y selección de antagonistas sobre bases científicas. Es laacción de un organismo para reducir la densidad poblacional de otro. Si bien la adopción del CB enla Argentina comenzó a principios del siglo XX, sigue siendo una disciplina poco desarrollada. Eneste contexto, diseñamos un cuestionario en línea de 15 preguntas para evaluar el estado actualdel CB de plagas, los aspectos sociales, económicos y demográficos de la disciplina en el país. Lacantidad de personas trabajando en CB en la actualidad es 122, siendo el 62% mujeres. Si bien laencuesta registró personas trabajando en CB en 17 jurisdicciones del país, la mayoría lo hace enBuenos Aires y el 82% lo hace en el sector público. El 74% de los proyectos tienen como objetivoel CB de artrópodos plaga, el cual se aborda mayormente mediante CB clásico. Si bien se registraun aumento en el número de personas trabajando en CB, brindamos una serie derecomendaciones tendientes a favorecer aún más el crecimiento de la disciplina en el país.Biological control (BC) can occur naturally (without human intervention), or by being applied intentionally when it is the result of research and the scientific selection of antagonists. It consists of the reduction in the population density of one species through the action of another. Although the adoption of applied BC in Argentina started at the beginning of the 20th century, it is still a developing discipline. In this context, we designed an online questionnaire consisting of 15 questions to assess the current status of pest BC and the social, economic and demographic aspects of the discipline in the country. We found that 122 people are currently working on BC, of which 62% are women. Although the survey revealed people working on BC in 17 jurisdictions of the country, most of the work is carried out in Buenos Aires, and 82% work in the public sector. Biological control of arthropod pests accounts for 74% of BC projects, which are mainly conducted through classical BC. Despite the fact there is an increase in the number of people working in BC, we offer a series of recommendations aimed at further favoring the growth of the discipline in the country.Fil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mc kay, Fernando. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Sosa, Alejandro Joaquín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Cecere, Maria Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Cingolani, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Maestro, Mariano. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Viscarret, Mariana Mabel. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Microbiología y Zoología Agrícola; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Biological control in Argentina: state of the art

El control biológico (CB) puede suceder en forma natural (sin intervención humana), oaplicado cuando es resultado del estudio y selección de antagonistas sobre bases científicas. Es laacción de un organismo para reducir la densidad poblacional de otro. Si bien la adopción del CB enla Argentina comenzó a principios del siglo XX, sigue siendo una disciplina poco desarrollada. Eneste contexto, diseñamos un cuestionario en línea de 15 preguntas para evaluar el estado actualdel CB de plagas, los aspectos sociales, económicos y demográficos de la disciplina en el país. Lacantidad de personas trabajando en CB en la actualidad es 122, siendo el 62% mujeres. Si bien laencuesta registró personas trabajando en CB en 17 jurisdicciones del país, la mayoría lo hace enBuenos Aires y el 82% lo hace en el sector público. El 74% de los proyectos tienen como objetivoel CB de artrópodos plaga, el cual se aborda mayormente mediante CB clásico. Si bien se registraun aumento en el número de personas trabajando en CB, brindamos una serie derecomendaciones tendientes a favorecer aún más el crecimiento de la disciplina en el país.Biological control (BC) can occur naturally (without human intervention), or by being applied intentionally when it is the result of research and the scientific selection of antagonists. It consists of the reduction in the population density of one species through the action of another. Although the adoption of applied BC in Argentina started at the beginning of the 20th century, it is still a developing discipline. In this context, we designed an online questionnaire consisting of 15 questions to assess the current status of pest BC and the social, economic and demographic aspects of the discipline in the country. We found that 122 people are currently working on BC, of which 62% are women. Although the survey revealed people working on BC in 17 jurisdictions of the country, most of the work is carried out in Buenos Aires, and 82% work in the public sector. Biological control of arthropod pests accounts for 74% of BC projects, which are mainly conducted through classical BC. Despite the fact there is an increase in the number of people working in BC, we offer a series of recommendations aimed at further favoring the growth of the discipline in the country.Fil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mc kay, Fernando. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Sosa, Alejandro Joaquín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Cecere, Maria Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Cingolani, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Maestro, Mariano. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Viscarret, Mariana Mabel. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Microbiología y Zoología Agrícola; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Lévy patterns in seabirds are multifaceted describing both spatial and temporal patterning

BACKGROUND: The flight patterns of albatrosses and shearwaters have become a touchstone for much of Lévy flight research, spawning an extensive field of enquiry. There is now compelling evidence that the flight patterns of these seabirds would have been appreciated by Paul Lévy, the mathematician after whom Lévy flights are named. Here we show that Lévy patterns (here taken to mean spatial or temporal patterns characterized by distributions with power-law tails) are, in fact, multifaceted in shearwaters being evident in both spatial and temporal patterns of activity. RESULTS: We tested for Lévy patterns in the at-sea behaviours of two species of shearwater breeding in the North Atlantic Ocean (Calonectris borealis) and the Mediterranean sea (C. diomedea) during their incubating and chick-provisioning periods. We found that distributions of flight durations, on/in water durations and inter-dive time-intervals have power-law tails and so bear the hallmarks of Lévy patterns. CONCLUSIONS: The occurrence of these statistical laws is remarkable given that bird behaviours are strongly shaped by an individual’s motivational state and by complex environmental interactions. Our observations could take Lévy patterns as models of animal behaviour to a new level by going beyond the characterisation of spatial movements to characterise how different behaviours are interwoven throughout daily animal life

Strong Host-Feeding Preferences of the Vector Triatoma infestans Modified by Vector Density: Implications for the Epidemiology of Chagas Disease

Chagas disease is a complex zoonosis with more than 150 mammalian host species, nearly a dozen blood-sucking triatomine species as main vectors, and 9–11 million people infected with Trypanosoma cruzi (its causal agent) in the Americas. Triatoma infestans, a highly domesticated species and one of the main vectors, feeds more often on domestic animals than on humans in northern Argentina. The question of whether there are host-feeding preferences among dogs, cats, and chickens is crucial to estimating transmission risks and predicting the effects of control tactics targeting them. This article reports the first host choice experiments of triatomine bugs conducted in small huts under natural conditions. The results demonstrate that T. infestans consistently preferred dogs to chickens or cats, with host shifts occurring more frequently at higher vector densities. Combined with earlier findings showing that dogs have high infection rates, are highly infectious, and have high contact rates with humans and domestic bugs, our results reinforce the role of dogs as the key reservoirs of T. cruzi. The strong bug preference for dogs can be exploited to target dogs with topical lotions or insecticide-impregnated collars to turn them into baited lethal traps or use them as transmission or infestation sentinels

Cost-Effectiveness of Chagas Disease Vector Control Strategies in Northwestern Argentina

Despite decreasing rates of prevalence and incidence, Chagas disease remains a serious problem in Latin America, especially for the rural poor. Without vaccines, control and prevention rely mostly on residual spraying of insecticides. Under the aegis of the Southern Cone Initiative, and in agreement with global trends in decentralization of the health systems, in 1992 the Argentinean vector control launched a new vector control program based on community participation. The present study represents the first thorough evaluation of the overall performance of such vector control program and the first comparative assessment of the cost-effectiveness of different vector control strategies in a highly endemic rural area of northwestern Argentina. Supported by results of independent studies, the present work shows that in rural, poor and dispersed areas of the Gran Chaco region, the implementation of a mixed (i.e., vertical attack phase followed by horizontal surveillance) strategy constantly supervised and supported by national or local vector control programs would be the most cost-effective option to interrupt vector-borne transmission of Chagas disease