Abstract To better understand the dispersion strategies of Triatoma infestans (Klug) (Hemiptera: Reduviidae, Triatominae), we evaluated the spatial effect of infested peridomicile and density vegetation cover in a historically endemic area for Chagas disease. The study was conducted in rural houses of the northwest of Córdoba province, Argentine, during 2012-2013. Active search of triatomines were made in domicile and peridomicile habitats. To characterize vegetation coverage, a thematic map was obtained considering five types of vegetation cover (closed/open forest, closed/open shrubland and cultural land). From each house we extracted the area of vegetation coverage, housing density and infested peridomiciles density. We used generalized linear models to evaluate the effect of these variables on the occurrence of infested peridomicile. According to our results, the probability of a peridomicile to be infested increases by 1.34 (95%CI [0.98; 1.90]) times more when peridomicile structures are in environments with higher housing density and by 1.25 (95%CI [0.84; 1.88]) more times when houses are surrounded by open shrublands. Among the multiple ecological determinants of peridomestic infestation, the influence of vegetation cover has been poorly studied. In this study we discussed the effect of the vegetation as a potential modulator of the dispersion strategies of T. infestans.

Triatoma infestans is the main vector of Chagas disease in the southern cone of South America. This species is well adapted to living in rural houses and structures used for housing domestic animals (peridomestic habitats). In this study, we evaluated the relationship between the source of blood consumed by adults of T. infestans collected from different peridomestic habitats from two localities from Cruz del Eje department (Córdoba, Argentina) and their nutritional and reproductive status. In each individual, the ratio between body weight and total body length was used as an indicator of nutritional status (NS). The presence of sperm in spermathecae and the number of chorionated oocytes in ovaries and oviducts were considered indicators of reproductive status (RS) of females. The feeding source in the promesenteron of male and female insects was identifed using anti-chicken, anti-goat, anti-human and anti-dog antisera. Chicken coops were the main peridomestic structure present in the study area as well as the peridomestic sites with the highest percentage of T. infestans. Insects collected from the different peridomestic structures showed a NS between 8 and 15 mg/mm. Of the evaluated females, 35.7% presented chorionated oocytes. Food profle analyses revealed that chicken was the main blood source. Independently of the blood source, the triatomines presented a NS between 8 and 15 mg/mm. No specimens feeding exclusively on human blood were found; nevertheless, of 31.48% of insects feeding on mixed blood sources, 59% included human blood. All T. infestansspecimens that included human blood in the mixed blood source were collected from chicken coops and storerooms located in a 12-m area around domiciles. Human blood present in mixed blood meal of adult insects suggests that T. infestansmoves from domiciles to peridomicilies and vice versa.

Triatoma infestans es el principal vector de la enfermedad de Chagas en el Cono Sur de Sudamérica. Esta especie está bien adaptada a vivir en el domicilio y estructuras utilizadas para albergar animales domésticos (hábitats peridomésticos). En este trabajo evaluamos la relación entre la fuente de sangre consumida por los adultos de T. infestans recolectados de diferentes hábitats peridomésticos de dos localidades del departamento de Cruz del Eje (Córdoba, Argentina) y su estado nutricional y reproductivo. En cada individuo, la relación entre el peso y la longitud corporal total se utilizó como un indicador del estado nutricional (EN). La presencia de espermatozoides en espermatecas y el número de ovocitos corionados en ovarios y oviductos se consideraron indicadores del estado reproductivo (ER) de las hembras. La fuente de alimentación en el promesenterón de insectos machos y hembras se identifcó utilizando antisueros anti-gallina, anti-cabra, anti-humano y anti-perro. Los gallineros fueron las principales estructuras peridomésticas presentes en el área de estudio, así como los sitios con el mayor porcentaje de T. infestans. Los insectos recolectados en las diferentes estructuras peridomésticas mostraron un EN entre 8 y 15 mg / mm. De las hembras evaluadas, el 35,7% presentó ovocitos corionados. Los análisis del perfl alimentario revelaron que las gallinas fueron la principal fuente de sangre. Independiente de la fuente de sangre los triatominos presentaron EN entre 8 y 15 mg / mm. No se encontraron ejemplares alimentados exclusivamente con sangre humana; sin embargo, del 31,48% de los insectos que se alimentaron de fuentes de sangre mixtas, el 59% incluía sangre humana. Todas las muestras de T. infestans que incluían sangre humana en la fuente de sangre se recolectaron en gallineros y depósitos ubicados en un área de 12 m alrededor de los domicilios. La sangre humana presente en las fuentes de alimentación mixta sugiere que T. infestans se mueve de los domicilios a los peridomicilios y viceversa.

Abstract INTRODUCTION: The domestic and peridomestic presence of Triatoma infestans depends on several factors, such as human behavior, vector behavior, ecology, and the environment. METHODS: This work was conducted in 139 domiciliary units, where triatomines were captured and risk factors in domiciles and peridomicilies were recorded. Household dwellers were interviewed to obtain information about practices regarding this disease and entomological indicators were calculated. RESULTS: Infestation indices were 59.7% for house compounds, 4.3% for domestic areas and 58.3% for the peridomestic areas. Intradomicile infestation was significantly associated with housing characteristics. The presence of chicken coops in peridomicilies was associated with an increased risk of infestation. Of the respondents, 80% did not recognize the importance of the peridomiciliary structures for triatomine control and had infested peridomicilies. CONCLUSIONS: The results show the importance of peridomiciles as refuge sites for Triatominae bugs; however, household dwellers do not perceive peridomiciles as areas that favor the presence of vectors. Actions for raising awareness about factors that favor the presence of triatomines are needed to improve the conditions of peridomiciliary environments.

Introduction In Triatominae, reproductive efficiency is an important factor influencing population dynamics, and a useful parameter in measuring a species' epidemiological significance as a vector of Trypanosoma cruzi (Chagas, 1909). The reproductive efficiency of triatomines is affected by food availability; hence, we measured and compared the effects of feeding frequency on the reproductive parameters of Triatoma patagonica (Del Ponte, 1929) and Triatoma infestans (Klug, 1934), and the effects of starvation on T. patagonica. Methods Couples from both species were fed weekly, or every 3 weeks; in addition, females in couples of T. patagonica were not fed. Each couple was observed weekly and reproductive efficiency was assessed on the following parameters: fecundity (eggs/female), fertility (eggs hatched/eggs laid), initiation and end of oviposition, initiation of mating, number of matings/week, and number of reproductive weeks. Relative meal size index (RMS), blood consumption index (CI), and E values (eggs/mg blood) were also calculated. Results Changes in feeding frequency affected the reproductive parameters of T. patagonica only, with a decrease in fecundity and number of reproductive weeks for those fed every 3 weeks, or not fed. The reproductive period, RMS index, and CI were lower for T. patagonica than T. infestans. However, despite the lower fecundity of T. patagonica, this species required less blood to produce eggs, with an E values of 2 compared to 2.94 for T. infestans. Conclusions Our results suggest that the differences in fecundity observed between species reflect the availability of food in their natural ecotopes.

In the context of Chagas Disease Control Programs schools play an important role in developing prevention and promotion activities, for which up to date and trained teachers are required. In order to assess teachers' knowledge of Chagas disease, elementary school teachers, in both rural (ER) and urban (EU) schools in Argentina in communities where there have been no educational interventions, were surveyed. The findings indicate that vector transmission is recognized by most teachers (91%) but there is a lack of knowledge of other modes of transmission. No teachers in rural areas and only 5.7% of teachers in urban areas mentioned congenital transmission. Opportunities for training were also limited and insufficient. The findings indicate the pervasive idea of Chagas disease being linked to ranches, bugs and rural areas, highlighting the need to train and prepare teachers on the subject.

En el marco de los Programas de Control de la enfermedad de Chagas las escuelas juegan un importante rol desarrollando actividades de prevención y promoción, para lo cual se requiere de docentes actualizados y capacitados. Con el objetivo de evaluar qué conocimientos tienen los docentes sobre la enfermedad de Chagas, se encuestó docentes de Nivel Primario de escuelas rurales (ER) y urbanas (EU) de Argentina pertenecientes a comunidades donde no se han realizado intervenciones educativas. Los resultados obtenidos indican que la transmisión vectorial es reconocida por la mayoría de los docentes (91%); sin embargo hay desconocimiento de otras vías. Ningún docente del área rural y sólo un 5.7% de los docentes de EU nombraron la vía congénita. Las oportunidades de capacitación también fueron escasas e insuficientes. Estos resultados ponen en evidencia la idea persistente de la enfermedad de Chagas ligada a ranchos, vinchucas y área rural, y pone de manifiesto la necesidad de formar y preparar a los docentes en esta temática.

Entre os vetores da doença de Chagas, Triatoma patagonica é uma espécie que se encontra em processo de adaptação ao ambiente humano; embora sua competência vetorial não seja bem conhecida. O estudo teve como objetivo avaliar e comparar padrões de alimentação e defecação em ninfas de quinto estádio de Triatoma patagonica e Triatoma infestans ad libitum. Os resultados mostraram que as ninfas de Triatoma patagonica apresentou padrõe de alimentação semelhante a Triatoma infestans. Sessenta e nove por cento e 58% das ninfas de Triatoma patagonica e Triatoma infestans respectivamente, realizaram a primeira defecação cinco minutos após de serem alimentadas; sendo que a primeira defecou durante a alimentação, com um tempo médio de dejeção menor do que para Triatoma infestans (3,4 vs 6,2 respectivamente). As ninfas de Triatoma patagonica foram capazes de defecar durante ou imediatamente após de se alimentarem.

Among the vectors of Chagas disease, Triatoma patagonica is a species in the process of adaptation to the human environment. However, its vector competence is not well known. This study had the aim of evaluating and comparing feeding and defecation patterns among fifth-instar nymphs of Triatoma patagonica and Triatoma infestans that were fed ad libitum. The results showed that nymphs of Triatoma patagonica had a feeding pattern similar to that of Triatoma infestans. Sixty nine percent and 58% of nymphs of Triatoma patagonica and Triatoma infestans, respectively, produced their first defecation within five minutes after being fed. Triatoma patagonica defecated during feeding, with an average time until first defecation that was shorter than that of Triatoma infestans (3.4 and 6.2 min, respectively). The nymphs of Triatoma patagonica were capable of defecating during or immediately after feeding.

Due to the importance of peridomestic populations in the reinfestation process of the domicile, the aim of this work was to evaluate the presence of triatomines in peridomiciles located in the San Francisco del Monte de Oro community, Ayacucho dept., Argentina. The presence of triatomines was evaluated in 18 peridomiciles between the months of October to March (2003/2004). The type of construction, host and number of triatomines were recorded for each peridomestic annex. The captured triatomines were taxonomically classified and their infectivity recorded. The 98.3 % of the triatomines corresponded to the species Triatoma infestans (Klug). The 79.3 % of the evaluated annex were found positive. The infestation indexes for goat corrals and chicken coops were 94.4 % and 54.5 %, respectively. There were no insects infected with Trypanosoma cruzi (Chagas). The corrals were differentiated in: stone pile, palisade and wood pile. Stone pile corrals showed larger number of triatomines than the palisade corrals (p< 0,05) Stone pile corrals seem to offer an adequate shelter for triatomines, probably due to the high number of empty spaces that offer and a higher difficulty for chemical control.

Debido a la importancia de las poblaciones peridomésticas en los procesos de reinfestación de las viviendas, el objetivo de este trabajo fue evaluar la presencia de triatominos en peridomicilios de la comuna de San Francisco del Monte de Oro, Dpto. Ayacucho, San Luis, Argentina. Se evaluó la presencia de triatominos en 18 peridomicilios entre los meses de Octubre a Marzo (2003/2004), para cada anexo se analizó: tipo de construcción, hospedador y número de triatominos. Los triatominos capturados fueron determinados taxonómicamente y se analizó su infectividad. El 98,3 % de los triatominos pertenecieron a la especie Triatoma infestans (Klug). El 79,3 % de los anexos evaluados fueron positivos. Los índices de infestación para corrales y gallineros fueron de 94,4? % y 54,5? %, respectivamente. No se encontraron insectos infectados con Trypanosoma cruzi (Chagas). Los corrales se diferenciaron en: pirca, empalizada y troncos apilados horizontalmente. En cuanto al número de triatominos, sólo se halló diferencia significativa entre los corrales de pirca y empalizada, siendo el primero mayor (p< 0,05). Los corrales de pirca parecen ser los más aptos para refugios de los triatominos, probablemente debido a la gran cantidad de espacios vacíos que ofrece y a una mayor dificultad para el control químico.

The objective of this paper was to validate tools for schoolchildren to help control Chagas disease vectors in their own homes. Two types of tables were produced, one reporting on the presence of risk factors in residences and the other to record the presence of triatomines. The materials were tested in the field by 100 students from an endemic area in Argentina and validated by technical personnel. The results obtained by students concerning the percentage of households with risk factors and vector-positive residences were similar to those obtained by the technical personnel. This information allowed teachers to classify the risk levels in the residences as at "high-risk", "risk", or "no risk". The information provides an important aid for health workers, and it is therefore recommended to include this educational strategy in the surveillance phase of the Chagas disease control program.

El objetivo de este trabajo fue validar herramientas para que escolares puedan vigilar sus viviendas. Se desarrollaron dos tipos de planillas, una sobre la presencia de factores de riesgos y otra para registrar la presencia de vinchucas en las viviendas. Estas planillas fueron puestas a prueba en campo por 100 escolares de escuelas de áreas endémicas de Argentina y validadas en campo por personal técnico. Los resultados obtenidos por los escolares sobre porcentajes de viviendas que presentan factores de riesgos y viviendas positivas fueron similares a los obtenidos por el personal técnico. La información recabada permitió a los docentes caracterizar las viviendas como "con mucho riesgo", "de riesgo" o "sin riesgo". Esta información sobre nivel de riesgo de las viviendas puede ser una importante ayuda para los agentes primarios de salud. Por lo tanto, se recomienda incluir estas estrategias educativas en los programas de control, en especial para la fase de vigilancia.

The objective of this paper was to validate tools for schoolchildren to help control Chagas disease vectors in their own homes. Two types of tables were produced, one reporting on the presence of risk factors in residences and the other to record the presence of triatomines. The materials were tested in the field by 100 students from an endemic area in Argentina and validated by technical personnel. The results obtained by students concerning the percentage of households with risk factors and vector-positive residences were similar to those obtained by the technical personnel. This information allowed teachers to classify the risk levels in the residences as at "high-risk", "risk", or "no risk". The information provides an important aid for health workers, and it is therefore recommended to include this educational strategy in the surveillance phase of the Chagas disease control program.

El objetivo de este trabajo fue validar herramientas para que escolares puedan vigilar sus viviendas. Se desarrollaron dos tipos de planillas, una sobre la presencia de factores de riesgos y otra para registrar la presencia de vinchucas en las viviendas. Estas planillas fueron puestas a prueba en campo por 100 escolares de escuelas de áreas endémicas de Argentina y validadas en campo por personal técnico. Los resultados obtenidos por los escolares sobre porcentajes de viviendas que presentan factores de riesgos y viviendas positivas fueron similares a los obtenidos por el personal técnico. La información recabada permitió a los docentes caracterizar las viviendas como "con mucho riesgo", "de riesgo" o "sin riesgo". Esta información sobre nivel de riesgo de las viviendas puede ser una importante ayuda para los agentes primarios de salud. Por lo tanto, se recomienda incluir estas estrategias educativas en los programas de control, en especial para la fase de vigilancia.

Among the vectors of Chagas disease, Triatoma guasayana (Wygodzinsky & Abalos) is a peridomestic species with epidemiological importance in Argentina. It could play an important role in the transmission of Trypanosoma cruzi (Chagas) to man, in areas where Triatoma infestans (Klug) had been eliminated by insecticide spraying. The aim of this work was to evaluate two aspects of vectorial competence: feeding behaviour and defaecation patterns, and to compare them with publihed data on Triatoma sordida (Stal). These processes were studied in fifth instar nymphs fed ad libitum on a restrained pigeon. The results show blood meal size controlling excretion behaviour. The first defaecation was emitted at 4.8 ± 9.2 min, with 87.5% of the insects defaecating during the first 10 min post-feeding. The comparison with T. sordida shows that both species have a similar pattern of feeding and defaecation behaviour.

Entre los vectores de la Enfermedad de Chagas, Triatoma guasayana (Wygodzinsky y Abalos) es un vector peridomiciliario de importancia epidemiológica en la Argentina, debido a que se comportaría como un vector secundario de Trypanosoma cruzi (Chagas), especialmente en áreas donde las poblaciones de Triatoma infestans (Klug) han sido temporalmente erradicadas por tratamiento con insecticidas. En este trabajo se evaluaron aspectos de la competencia vectorial de ninfas V de T. guasayana relacionados con su patrón de alimentación y excreción, para compararlos luego con datos ya publicados de Triatoma sordida (Stal). Estos procesos fueron estudiados en insectos alimentados ad libitum sobre paloma. Los resultados obtenidos indican una estrecha relación entre tamaño de la ingesta y patrón de excreción. El tiempo medio de emisión de la primera deyección fue de 4,8 ± 9,2 min y el 87.5% de las ninfas defecó dentro de los primeros 10 min post-ingesta. La relación entre tamaño de la ingesta y tiempo de emisión de la primera deyección fue significativa (r= -0,32). La comparación con T. sordida muestra que ambas especies poseen patrones similares en cuanto a los hábitos de alimentación y excreción.

Among the vectors of Chagas disease, Triatoma patagonica is a species in the process of adaptation to the human environment being recently registered in urban and suburban zones. However, its importance as a vector of Chagas disease is unknown. The aim of this work was to evaluate two aspects of vectorial competence: the feeding behaviour and the defaecation pattern. These processes were studied in females of T. patagonica fed ad libitum on a restrained pigeon. The results showed that the blood meal size was negatively correlated with the time of first defaecation (r = -0.42). The first defaecation was emitted before the first 10 min and defaecations during feeding were frequent. A total of 73% of females, defaecated during the first 30 min post-feeding. These results suggest that if this species subsequently colonizes the domicile, it would be capable of transmitting Trypanosoma cruzi.

Currently, Chagas' disease control consists mainly of chemical warfare against the insect vector. However, a number of risk factors, such as poor hygiene and clutter, can facilitate the persistence of triatomine breeding sites. Relying on the premise that communities at risk of Chagas have little knowledge about the disease, the authors defined the extent of knowledge that is considered optimal and determined how much is known, on average, by the inhabitants of two areas in Argentina showing different epidemiologic trends. Risk factors in both areas were identified. The optimal extent of knowledge was defined in accordance with 25 "basic concepts" surrounding the disease, and from these questionnaires were constructed for evaluating average knowledge about the disease. Results obtained showed that risk factors were linked primarily with the type of dwelling construction and with clutter, as well as with limited knowledge about the disease. There was little basic knowledge about Chagas, with an inability, for example, to identify the vector and describe the mode of transmission. Increasing people's knowledge about the disease would be an important step in the fight against Chagas and would give the inhabitants of endemic areas a better understanding of their situation as well as the chance to develop behaviors that would allow them to assume responsibility for their own welfare.

Actualmente, el control de la enfermedad de Chagas se basa en acciones químicas contra la vinchuca. Sin embargo, existen factores de riesgo como la falta de higiene y el desorden que serían responsables de la persistencia de focos de triatominos. Teniendo en cuenta que las comunidades expuestas al riesgo de contraer la enfermedad poseen escasos conocimientos sobre ella, se definió el nivel óptimo de conocimientos y se determinó el nivel medio de conocimientos de los habitantes de dos zonas epidemiológicamente diferentes de Argentina y se identificaron los factores de riesgo presentes en ambas. El nivel óptimo de conocimientos se definió por 25 "nociones elementales" sobre la enfermedad, a partir de las cuales se elaboraron los cuestionarios para evaluar el nivel medio de conocimientos. Los resultados obtenidos reflejaron un predominio de los factores de riesgo relacionados con la construcción de las viviendas y el desorden y un limitado nivel de conocimientos sobre la enfermedad. Resultó deficiente el conocimiento de información básica sobre la enfermedad, relacionada, por ejemplo, con el reconocimiento de las ninfas y el mecanismo de transmisión. Un mejor conocimiento del tema supondría un importante avance en la lucha contra la enfermedad de Chagas, conduciendo a los habitantes de áreas endémicas a una mejor comprensión de su realidad y a la adquisición de hábitos que les permitan ser los protagonistas de su propio bienestar.

Different blood consumption speed was observed in Triatoma infestans - nymphs and adults - exposed to 12 degrees C and 28 degrees C. Exposure to optimal temperature (28 degrees C) allows the insects to consume blood at a rate of 9% per day. Significative relationship between blood amount present in the promesenteron and consumed blood was found at 28 degrees. Consumption of blood was drastically reduced at the lowest temperature. Accordingly, lack of ovaric development, oviposition and mating behaviour was observed in insects kept at 12 degrees C. Relationship between laboratory and field observations are discussed.