Análisis de materiales didácticos e informativos sobre dengue en Argentina / Analysis of didactic and informative materials about dengue in Argentina / Análise de materiais didáticos e informativos sobre dengue na Argentina

Presentamos un análisis de materiales didácticos e informativos sobre dengue, elaborados por Ministerios de Salud y Educación de diferentes jurisdicciones de Argentina. Realizamos un análisis de contenido indagando dimensiones de la salud, modelos didácticos, modelos epidemiológicos y concepciones acerca de participación. Inferimos que la perspectiva dominante tuvo una fuerte impronta biomédica, desde un modelo epidemiológico lineal multicausal. El eje principal fue el "manejo de criaderos", acciones para reducir los recipientes domésticos con agua en los que se cría el mosquito Aedes aegypti. Si bien la participación de la comunidad apareció como central, la concepción subyacente fue de pseudoparticipación (la comunidad como ejecutora de recomendaciones, sin injerencia en las decisiones). Finalmente, si bien en las fundamentaciones de las propuestas didácticas inferimos una intencionalidad constructivista, en la mayoría de las actividades identificamos un modelo de transmisión-recepción.

We present an analysis of didactic and informative materials about dengue elaborated by Health and Education Ministries of Argentina. We performed Content Analysis inquiring aspects regarding health dimensions, didactic models, epidemiological models and participation concepts. We inferred that the dominant perspective had a strong biomedical imprint within a linear multicausal model. The main focus was "breeding site reduction", actions to diminish domestic water-holding containers where Aedes aegypti breeds. Regardless of the importance given to participation, the underlying concept was pseudo participation (the community as mere target for recommendations, without influence in decisions). Finally, despite finding constructivist intentions in the introductions of didactical materials, we identified a transmission-reception model in most activities.

Apresentamos uma análise de materiais didáticos e informativos sobre dengue produzidos pelos Ministérios da Saúde e da Educação da Argentina. Realizamos uma Análise de Conteúdo indagando sobre dimensões da saúde, modelos didáticos, modelos epidemiológicos e conceitos de participação. Nós inferimos que a perspectiva dominante foi biomédica a partir de um modelo linear multi-causal. O foco principal foi ações de "redução de criadouros" para diminuir recipientes com água para uso doméstico, onde o Aedes aegypti cria-se. Não obstante a centralidade da participação, o conceito subjacente foi pseudoparticipação (a comunidade como destinatária de recomendações, sem influência nas decisões). Finalmente, apesar de identificar intenções construtivistas nas introduções dos materiais didáticos, caracterizamos um modelo de transmissão-recepção nas atividades.

Presence of antigen-experienced T cells with low grade of differentiation and proliferative potential in chronic Chagas disease myocarditis.

BACKGROUND: The main consequence of chronic Trypanosoma cruzi infection is the development of myocarditis in approximately 20-30% of infected individuals but not until 10-20 years after the initial infection. We have previously shown that circulating interferon-γ-secreting T cells responsive to Trypanosoma cruzi antigens in chronic Chagas disease patients display a low grade of differentiation and the frequency of these T lymphocytes decreases along with the severity of heart disease. This study thought to explore the expression of inhibitory receptors, transcription factors of type 1 or regulatory T cells, and markers of T cell differentiation, immunosenescence or active cell cycle in cardiac explants from patients with advanced Chagas disease myocarditis. METHODOLOGY/PRINCIPAL FINDINGS: The expression of different markers for T and B cells as well as for macrophages was evaluated by immunohistochemistry and immunofluorescence techniques in cardiac explants from patients with advanced chronic Chagas disease submitted to heart transplantation. Most infiltrating cells displayed markers of antigen-experienced T cells (CD3(+), CD4(+), CD8(+), CD45RO(+)) with a low grade of differentiation (CD27(+), CD57(-), CD45RA(-), PD(-)1(-)). A skewed T helper1/T cytotoxic 1 profile was supported by the expression of T-bet; whereas FOXP3(+) cells were scarce and located only in areas of severe myocarditis. In addition, a significant proliferative capacity of CD3(+) T cells, assessed by Ki67 staining, was found. CONCLUSIONS/SIGNIFICANCE: The quality of T cell responses and immunoregulatory mechanisms might determine the pattern of the cellular response and the severity of disease in chronic Trypanosoma cruzi infection.

Spatial analysis of Aedes aegypti immatures in Northern Argentina: clusters and temporal instability.

The objective of this study was to analyze the spatio-temporal patterns of Aedes aegypti immatures based on four entomological surveys that inspected over 6000 households in a large neighborhood of the city of Clorinda between 2007 and 2008. Global and local spatial point pattern analyses of immature presence or absence, habitat quality (estimated using a previously obtained statistical model) and pupal production were performed. Global analyses showed aggregation of both infestation and habitat quality up to 10 times bigger than previously described, ranging from 150 to 400m between surveys. Pupal production was also clustered but at smaller scales than infestation presence/absence. The location of the clusters was temporally unstable between surveys. There was no spatial structure related to the control strategy; lots treated with temephos and lots uninspected (i.e., closed or refusing) were randomly distributed. These results suggest a combination of exogenous (the aggregation of better quality habitats) and endogenous (dispersal) processes explaining the observed patterns of larger-scale infestation. A spatial targeting strategy at the neighborhood scale would not be as cost-effective in Clorinda as in other sites where stable smaller-scale clusters permit the identification of key premises.

Water use practices limit the effectiveness of a temephos-based Aedes aegypti larval control program in Northern Argentina.

BACKGROUND: A five-year citywide control program based on regular application of temephos significantly reduced Aedes aegypti larval indices but failed to maintain them below target levels in Clorinda, northern Argentina. Incomplete surveillance coverage and reduced residuality of temephos were held as the main putative causes limiting effectiveness of control actions. METHODOLOGY: The duration of temephos residual effects in household-owned water-holding tanks (the most productive container type and main target for control) was estimated prospectively in two trials. Temephos was applied using spoons or inside perforated small zip-lock bags. Water samples from the study tanks (including positive and negative controls) were collected weekly and subjected to larval mortality bioassays. Water turnover was estimated quantitatively by adding sodium chloride to the study tanks and measuring its dilution 48 hs later. PRINCIPAL FINDINGS: The median duration of residual effects of temephos applied using spoons (2.4 weeks) was significantly lower than with zip-lock bags (3.4 weeks), and widely heterogeneous between tanks. Generalized estimating equations models showed that bioassay larval mortality was strongly affected by water type and type of temephos application depending on water type. Water type and water turnover were highly significantly associated. Tanks filled with piped water had high turnover rates and short-lasting residual effects, whereas tanks filled with rain water showed the opposite pattern. On average, larval infestations reappeared nine weeks post-treatment and seven weeks after estimated loss of residuality. CONCLUSIONS: Temephos residuality in the field was much shorter and more variable than expected. The main factor limiting temephos residuality was fast water turnover, caused by householders' practice of refilling tanks overnight to counteract the intermittence of the local water supply. Limited field residuality of temephos accounts in part for the inability of the larval control program to further reduce infestation levels with a treatment cycle period of 3 or 4 months.

Effects of a five-year citywide intervention program to control Aedes aegypti and prevent dengue outbreaks in northern Argentina.

BACKGROUND: Dengue has propagated widely through the Americas. Most countries have not been able to maintain permanent larval mosquito control programs, and the long-term effects of control actions have rarely been documented. METHODOLOGY: The study design was based on a before-and-after citywide assessment of Aedes aegypti larval indices and the reported incidence of dengue in Clorinda, northeastern Argentina, over 2003-2007. Interventions were mainly based on focal treatment with larvicides of every mosquito developmental site every four months (14 cycles), combined with limited source reduction efforts and ultra-low-volume insecticide spraying during emergency operations. The program conducted 120,000 house searches for mosquito developmental sites and 37,000 larvicide applications. PRINCIPAL FINDINGS: Random-effects regression models showed that Breteau indices declined significantly in nearly all focal cycles compared to pre-intervention indices clustered by neighborhood, after allowing for lagged effects of temperature and rainfall, baseline Breteau index, and surveillance coverage. Significant heterogeneity between neighborhoods was revealed. Larval indices seldom fell to 0 shortly after interventions at the same blocks. Large water-storage containers were the most abundant and likely to be infested. The reported incidence of dengue cases declined from 10.4 per 10,000 in 2000 (by DEN-1) to 0 from 2001 to 2006, and then rose to 4.5 cases per 10,000 in 2007 (by DEN-3). In neighboring Paraguay, the reported incidence of dengue in 2007 was 30.6 times higher than that in Clorinda. CONCLUSIONS: Control interventions exerted significant impacts on larval indices but failed to keep them below target levels during every summer, achieved sustained community acceptance, most likely prevented new dengue outbreaks over 2003-2006, and limited to a large degree the 2007 outbreak. For further improvement, a shift is needed towards a multifaceted program with intensified coverage and source reduction efforts, lids or insecticide-treated covers to water-storage containers, and a broad social participation aiming at long-term sustainability.