Environmental characteristics around the household and their association with hookworm infection in rural communities from Bahir Dar, Amhara Region, Ethiopia.

Soil-Transmitted Helminths (STH) are highly prevalent Neglected Tropical Disease in Ethiopia, an estimated 26 million are infected. Geographic Information Systems and Remote Sensing (RS) technologies assist data mapping and analysis, and the prediction of the spatial distribution of infection in relation to environmental variables. The influence of socioeconomic, environmental and soil characteristics on hookworm infection at the individual and household level is explored in order to identify spatial patterns of infection in rural villages from Zenzelema (Amhara region). Inhabitants greater than 5 years old were recruited in order to assess the presence of STH. Socioeconomic and hookworm infection variables at the household level and environmental variables and soil characteristics using RS were obtained. The dominant STH found was hookworm. Individuals which practiced open defecation and those without electricity had a significant higher number of hookworm eggs in their stool. Additionally, adults showed statistically higher hookworm egg counts than children. Nonetheless, the probability of hookworm infection was not determined by socioeconomic conditions but by environmental characteristics surrounding the households, including a combination of vigorous vegetation and bare soil, high temperatures, and compacted soils (high bulk density) with more acidic pH, given a pH of 6.0 is optimal for hatching of hookworm eggs. The identification of high-risk environmental areas provides a useful tool for planning, targeting and monitoring of control measures, including not only children but also adults when hookworm is concerned.

Evaluation and planning of Chagas control activities using geospatial tools.

Chagas continues to be a relevant public health problem in Latin America. In this work, we present a spatiotemporal analysis applied for the evaluation and planning of Chagas vector control strategies. We analysed the spatial distribution of the vector Triatoma infestans infestation related to ongoing control interventions cycles in rural communities near Añatuya, Santiago del Estero, Argentina. A geographical information system was developed for the spatial analysis obtaining, for each house, variables that describe the history of spraying and infestation at each time of interventions. Bi-dimensional histograms were used to describe the spatiotemporal pattern of these activities and peri-domestic infestation at the last intervention was modelled by a neural network model. We qualitatively evaluate control programmes considering the history of infestation and spraying from a spatiotemporal point of view, incorporating new ways of visualising this information. Predictions are based on novel, non-linear models and spatiotemporal indices, which should be useful for strategically allocating Chagas control resources in the future and thus help to better plan spraying strategies.

Spatial analyzes of triatomine infestation indices and their association to the actions of a Chagas disease program and environmental variables during a 5-year intervention period.

Vector control of Chagas disease in the past decades has been mainly based on chemical control. Fundación Mundo Sano is implementing an Integral Chagas Program in a rural area of the Argentinean Gran Chaco Region since 2002. The objective of this study was to analyze both, temporal and spatial variation of infestation indices and their relation to the actions of the Program and environmental variables as land and vegetation cover changes, during a 5 year intervention period (2010-2014). Triatoma infestans infestation data from five rural localities from the Province of Santiago del Estero (Argentina) was analyzed in order to detect spatial aggregation. Differences in control effectiveness were observed between the peridomicile and intradomicile: infestation indices were higher in the peridomicile, recurrent infestation was present only in the peridomicile while low level infestation clusters were absent in the peridomicile. Cluster zones with low intradomestic infestation had larger proportions of bare soil and thin vegetation. In contrast, cluster zones with high intradomestic infestation had higher forest vegetation proportions and smaller cultivated area proportions. Spatial statistics analysis detected differences in cluster patterns between intra and peridomestic infestation suggesting that control actions should be based on geographical areas and not on political units. This work brings together different approaches to analyze infestation levels at the fine spatial scale, which could be used as a base for risk spatial stratification.

Estratificación de riesgo de eventos de salud/enfermedad asociados a inundaciones / Risk stratification of health/disease events associated with floods

INTRODUCCIÓN Los desastres naturales de origen atmosférico, geológico ó hídrico son eventos catastróficos que provocan consecuencias en el ámbito de la salud, con fuertes impactos económicos y sociales. El impacto sobre el bienestar de la población expuesta no sólo está dado por habitar zonas afectadas por las inundaciones, sino también por los modos de vida y sus condicionantes. El concepto de riesgo posibilita seleccionar algunos factores que permiten generar intervenciones/recomendaciones, a través de acciones puntuales y específicas con aspectos bioecológicos y socioculturales. OBJETIVO Elaborar, evaluar y validar una herramienta dinámica que permita planificar e implementar acciones oportunas de prevención y mitigación de daños para la salud, ante la potencial ocurrencia de inundaciones o precipitaciones mayores a la media histórica estacional. MÉTODOS El estudio, analítico y de diseño transversal, incluye los departamentos de la cuenca del Plata por ser esta la cuenca del país más afectada por eventos de inundaciones. Se identificaron las posibles enfermedades que pudiesen ocurrir durante y después de una inundación; leptospirosis, dengue-chikungunya-zika, picadura de animales ponzoñosos, diarrea, hepatitis, y enfermedades respiratorias agudas. Se determinaron variables sociodemográficas, económicas y ambientales, relacionadas con procesos de salud-enfermedad-atención y cuidado, así como la respuesta social organizada para cada uno de los seis eventos. Posteriormente se hizo una selección de expertos para cada enfermedad quienes, utilizando el método propuesto por Saaty ponderaron los factores de amenazas y vulnerabilidad (determinantes del riesgo). RESULTADOS El riesgo de ocurrencia de diarreas en población de un departamento, de acuerdo con los expertos, está asociado con el porcentaje de área inundada; las condiciones en las que vive la población, la falta de accesibilidad y disponibilidad de agua segura, la falta de desagüe cloacal a red pública, condiciones de hacinamiento, la densidad poblacional y las limitaciones de acceso a los servicios de salud. DISCUSIÓN En relación a las fuentes de información, tanto su representatividad (en este caso, fuentes secundarias) como su temporalidad (ej. censo 2010) pueden ser mejoradas y actualizadas cuando estén disponibles para mejorar las precisiones de esta herramienta. Se entiende que dichas limitaciones podrían impactar directamente sobre las decisiones concretas para planificar e implementar acciones oportunas de prevención y mitigación de daños para la salud priorizando o no adecuadamente un departamento por sobre otro, por lo que se ve la necesidad de seguir revisando todo el procedimiento de ejecución de la presente metodología

River pollution remediation monitored by optical and infrared high-resolution satellite images.

The Bormida River Basin, located in the northwestern region of Italy, has been strongly contaminated by the ACNA chemical factory. This factory was in operation from 1892 to 1998, and contamination from the factory has had deleterious consequences on the water quality, agriculture, natural ecosystems and human health. Attempts have been made to remediate the site. The aims of this study were to use high-resolution satellite images combined with a classical remote sensing methodology to monitor vegetation conditions along the Bormida River, both upstream and downstream of the ACNA chemical factory site, and to compare the results obtained at different times before and after the remediation process. The trends of the Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) along the riverbanks are used to assess the effect of water pollution on vegetation. NDVI and EVI values show that the contamination produced by the ACNA factory had less severe effects in the year 2007, when most of the remediation activities were concluded, than in 2006 and 2003. In 2007, the contamination effects were noticeable up to 6 km downstream of the factory, whereas in 2003 and 2006 the influence range was up to about 12 km downstream of the factory. The results of this study show the effectiveness of remediation activities that have been taking place in this area. In addition, the comparison between NDVI and EVI shows that the EVI is more suitable to characterise the vegetation health and can be considered an additional tool to assess vegetation health and to monitor restoration activities.

An operative dengue risk stratification system in Argentina based on geospatial technology.

Based on an agreement between the Ministry of Health and the National Space Activities Commission in Argentina, an integrated informatics platform for dengue risk using geospatial technology for the surveillance and prediction of risk areas for dengue fever has been designed. The task was focused on developing stratification based on environmental (historical and current), viral, social and entomological situation for >3,000 cities as part of a system. The platform, developed with open-source software with pattern design, following the European Space Agency standards for space informatics, delivers two products: a national risk map consisting of point vectors for each city/town/locality and an approximate 50 m resolution urban risk map modelling the risk inside selected high-risk cities. The operative system, architecture and tools used in the development are described, including a detailed list of end users' requirements. Additionally, an algorithm based on bibliography and landscape epidemiology concepts is presented and discussed. The system, in operation since September 2011, is capable of continuously improving the algorithms producing improved risk stratifications without a complete set of inputs. The platform was specifically developed for surveillance of dengue fever as this disease has reemerged in Argentina but the aim is to widen the scope to include also other relevant vector-borne diseases such as chagas, malaria and leishmaniasis as well as other countries belonging to south region of Latin America.