Chagas pediátrico en áreas rurales de la provincia de Santa Fe / Pediatric chagas disease in rural areas of Santa Fe province

INTRODUCCIÓN: la enfermedad de Chagas continúa siendo un importante problema de salud pública en la ecoregión del Gran Chaco. El norte de la provincia de Santa Fe, correspondiente al Sur de dicha región, se encuentra bajo control entomológico. Dado que se trata de una infección crónica, la seroprevalencia de esta endemia enniños es un marcador de la situación actual de la infección. OBJETIVOS:Determinar la seroprevalencia de infección chagásica en poblaciónpediátrica del Chaco santafesino. MÉTODOS: Se realizó un estudiodescriptivo de corte transversal sobre seroprevalencia de infección chagásica en niños de 5 a 14 años de edad. Comprendió un área aproximada de 38 000 km2 de distritos rurales de los departamentos 9 de Julio y Vera en la provincia de Santa Fe, y se llevó a cabo entre noviembre de 2010 y abril de 2013. RESULTADOS: Se muestreó al71,5% de los niños de la región (3765/5266). La prevalencia fue de1,8% (67/3765). Varió de 5,5% a 0% entre los distintos distritos. De5 a 9 años, fue 1,2% (21/1769); de 10 a 14 años, 2,3% (46/1996).CONCLUSIONES: La seroprevalencia hallada fue inferior a la de otrosestudios en el Gran Chaco. Se observa una gran heterogeneidad en laprevalencia entre los distritos, aun entre los vecinos. La distribución noobedecería a factores climáticos, sino a factores sociales y a la influenciade la actividad antrópica en cada localidad.

INTRODUCTION: chagas disease remains a major public health problem in the Gran Chaco region. The north of Santa Fe province, being the south of this region, is under entomologicalsurveillance. Being a chronic infection, the seroprevalence of this endemic disease in children serves as a marker of the current status. OBJECTIVES: To determine the seroprevalence of Chagasdisease in the pediatric population of Chaco region in Santa Fe. METHODS: A descriptive, cross-sectional seroprevalence study on Chagas infection was conducted for children aged 5-14 years old. It considered an area of 38 000 km2 belonging to ruraldistricts of 9 de Julio and Vera departments in Santa Fe province,between November 2010 and April 2013. RESULTS: The sampling included 71.5% of the children in the region (3765/5266). There was a prevalence of 1.8% (67/3765), ranged from 5.5% to 0% among districts. For 5-9 years, it was 1.2% (21/1769); for 10-14 years, 2.3% (46/1996). CONCLUSIONS: The seroprevalence was lower than in other studies performed in the Gran Chaco. A large heterogeneity is observed in the prevalence among districts, even among neighboring districts. The distribution does not seem to be due to climatic factors, but to social factors and the influence of human activity in each location.

Where do these bugs come from? Phenotypic structure of Triatoma infestans populations after control interventions in the Argentine Chaco

House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (re-infestant bugs) Triatoma infestans populations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to < 1% during a four-year follow-up, unlike our previous studies in the neighbouring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray groups were significantly different, suggesting that re-infestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both areas supported the existence of independent re-infestation processes within the same district. These results point to local heterogeneities in house re-infestation dynamics and emphasise the need to expand the geographic coverage of vector surveillance and control operations to the affected region.

Is imidacloprid an effective alternative for controlling pyrethroid-resistant populations of Triatoma infestans (Hemiptera: Reduviidae) in the Gran Chaco ecoregion?

The prevention of Chagas disease is based primarily on the chemical control of Triatoma infestans (Klug) using pyrethroid insecticides. However, high resistance levels, correlated with control failures, have been detected in Argentina and Bolivia. A previous study at our laboratory found that imidacloprid could serve as an alternative to pyrethroid insecticides. We studied the delayed toxicity of imidacloprid and the influence of the blood feeding condition of the insect on the toxicity of this insecticide; we also studied the effectiveness of various commercial imidacloprid formulations against a pyrethroid-resistant T. infestans population from the Gran Chaco ecoregion. Variations in the toxic effects of imidacloprid were not observed up to 72 h after exposure and were not found to depend on the blood feeding condition of susceptible and resistant individuals. Of the three different studied formulations of imidacloprid on glass and filter paper, only the spot-on formulation was effective. This formulation was applied to pigeons at doses of 1, 5, 20 and 40 mg/bird. The nymphs that fed on pigeons treated with 20 mg or 40 mg of the formulation showed a higher mortality rate than the control group one day and seven days post-treatment (p < 0.01). A spot-on formulation of imidacloprid was effective against pyrethroid-resistant T. infestans populations at the laboratory level.

Exploring the association between Trypanosoma cruzi infection in rural communities and environmental changes in the southern Gran Chaco

The association between land use and land cover changes between 1979-2004 in a 2.26-million-hectare area south of the Gran Chaco region and Trypanosoma cruzi infection in rural communities was analysed. The extent of cultural land, open and closed forests and shrubland up to 3,000 m around rural communities in the north, northwest and west of the province of Córdoba was estimated using Landsat satellite imagery. The T. cruzi prevalence was estimated with a cross-sectional serological survey conducted in the rural communities. The land cover showed the same patterns in the 1979, 1999 and 2004 satellite imagery in both the northwest and west regions, with shrinking regions of cultured land and expanding closed forests away from the community. The closed forests and agricultural land coverage in the north region showed the same trend as in the northwest and west regions in 1979 but not in 1999 or 2004. In the latter two years, the coverage remote from the communities was either constant or changed in opposite ways from that of the northwest and west regions. The changes in closed forests and cultured vegetation alone did not have a significant, direct relationship with the occurrence of rural communities with at least one person infected by T. cruzi. This study suggests that the overall decrease in the prevalence of T. cruzi is a consequence of a combined effect of vector control activities and changes in land use and land cover.

Applied biodiversity science: Bridging ecology, culture, and governance for effective conservation / Ciencia aplicada en biodiversidad: Integrando ecología, cultura y gobernancia para la conservación efectiva / Ciência aplicada em biodiversidade: Integrando ecologia, cultura e governancia para a conservação efetiva

Solutions to the biodiversity crisis will ultimately come from biological scientists and social scientists working in tandem, yet disconnects among scientific disciplines, conservation institutions, and practical implementation hinder effective conservation. The vision of Applied Biodiversity Science (ABS) is to achieve integration between biodiversity research and on-the-ground conservation practices. Three pillars support ABS: 1) integrated social and biological research; 2) cross-disciplinary collaboration with local conservation institutions and actors; and 3) application of conservation theory to practice. Our ABS program, including a doctoral training program, is focused on two cross-cutting themes: Ecological Functions and Biodiversity; and Communities and Governance. The research integration matrix matches causes of biodiversity loss against research approaches, and is thus a useful tool for defining integrative questions and building interdisciplinary research teams. Case studies from Western Amazon and Gran Chaco illustrate how the ABS model has been implemented in the Americas. The intention is that ABS approaches will produce conservation scientists who communicate effectively across disciplines, and make their research relevant to ongoing programs. The ABS approach helps elucidate how and why ecosystem functions, biodiversity, human communities and governance systems are interconnected.

Las soluciones para la crisis de biodiversidad serán generadas finalmente a partir del trabajo conjunto de científicos naturales y sociales. Pero la desconexión entre disciplinas, instituciones conservacionistas y la implementación de conocimientos impiden la conservación efectiva. La visión de la Ciencia de Biodiversidad Aplicada (CBA) es lograr la integración entre investigación sobre biodiversidad y la práctica de la conservación. Tres pilares sustentan esta propuesta: 1) investigación biológica y social integrada; 2) colaboración entre disciplinas con instituciones y actores locales que trabajan en conservación; y 3) implementación práctica de teorías sobre conservación. Nuestro programa CBA incluye un programa para estudiantes de doctorado y está enfocado en dos temas de investigación: funciones ecológicas y biodiversidad, y comunidades y gobernabilidad. La matriz integrada de investigación relaciona las causas de la pérdida de biodiversidad con los enfoques de la investigación, siendo una herramienta útil para definir hipótesis integradas y formar equipos interdisciplinarios de investigación. Estudios de casos de Amazonia y el Gran Chaco demuestran cómo implementamos el modelo de CBA en Suramérica. La intención es que el enfoque CBA produzca científicos de la conservación que se comuniquen efectivamente entre disciplinas y sus estudios sean relevantes para los programas en ejecución. El enfoque planteado ayudaría a iluminar cómo y porqué las funciones de los ecosistemas, la biodiversidad, las comunidades humanas y los sistemas de gobernabilidad están interconectadas.

As soluções para a crise de biodiversidade serão geradas finalmente apartir do trabalho conjunto de cientistas naturais e sociais. Mas a desconexão entre disciplinas, instituições conservacionistas e a implementação de conhecimentos impedem a conservação efetiva. A visão da Ciência de Biodiversidade Aplicada (CBA) é conseguir a integração entre investigação sobre biodiversidade e a prática da conservação. Três pilares sustentam esta proposta: 1) investigação biológica e social integrada; 2) colaboração entre disciplinas com instituições e atores locais que trabalham em conservação; e 3) implementação prática de teorias sobre conservação. Nosso programa CBA inclui um programa para estudantes de doutorado e está focado em dois temas de investigação: funções ecológicas e biodiversidade, e comunidades e governabilidade. A matriz integrada de investigação relaciona as causas da perda de biodiversidade com as abordagens da investigação, sendo uma ferramenta útil para definir hipóteses integradas e formar equipes interdisciplinárias de investigação. Estudos de casos da Amazônia e o Gran Chaco demonstram como implementamos o modelo de CBA na América do sul. A intenção é de que a abordagem CBA gere cientistas da conservação que se comuniquem efetivamente entre disciplinas e seus estudos sejam relevantes para os programas em execução. A abordagem sugerida ajudaria a iluminar como e porquê as funções dos ecossistemas, a biodiversidade, as comunidades humanas e os sistemas de governabilidade estão interconectadas.

Response of Triatoma infestans to pour-on cypermethrin applied to chickens under laboratory conditions

This article reports the effects of a pour-on formulation of cypermethrin (6 percent active ingredient) applied to chickens exposed to Triatoma infestans, the main vector of Chagas disease in rural houses of the Gran Chaco Region of South America. This study was designed as a completely random experiment with three experimental groups and five replicates. Third instar nymphs were fed on chickens treated with 0, 1 and 2 cc of the formulation. Nymphs were allowed to feed on the chickens at different time intervals after the insecticide application. Third-instar nymphs fed on treated chickens showed a higher mortality, took less blood during feeding and had a lower moulting rate. The mortality rate was highest seven days after the insecticide solution application and blood intake was affected until 30 days after the application of the solution.

Los estudios sobre medicina y farmacopea vernácula en el gran Chaco / Studies on medicine and pharmacopoeia vernacular in the gran Chaco

Se evalúa la situación del conocimiento referido a la medicina y la farmacopea vernácula entre grupos humanos del Gran Chaco. El análisis y reseña se basa en la revisión de aportes bibliográficos correspondientes a diversas disciplinas. Se eligieron las contribuciones más significativas y específicas sobre el tema, excluyéndose como fin la exhaustividad. Se hace una semblanza sobre los grupos humanos tratados, así como de los tópicos resaltantes de la etnomedicina indígena y criolla y la farmacopea propia de ambos colectivos. Se discuten los logros alcanzados y las carencias que aún persisten. Se proponen líneas y orientaciones para fortalecer las investigaciones en temáticas poco tratadas o aún no encaradas.