Institute Altos Estudios Espaciales Mario Gulich

Córdoba, Argentina

Institute Altos Estudios Espaciales Mario Gulich

Córdoba, Argentina
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Scavuzzo C.M.,Institute Altos Estudios Espaciales Mario Gulich | Introini M.V.,Misterio de Salud de la Nacion | Zaidenberg M.,Misterio de Salud de la Nacion
Vector-Borne and Zoonotic Diseases | Year: 2011

Dengue has affected the north provinces of Argentina, mainly Salta province. The 2009 outbreak, with 5 deaths and >27,000 infected, was the most important, and the first to extend into the central area of the country. This article includes research on seasonal Aedes aegypti abundance variation in Orán City (Salta province), and determination of the date of mosquito population increase and an estimation of the date of maximum rate of increase as well as the intrinsic rate of natural increase (r), to detect the optimal time to apply vector control measures. Between September 2005 and March 2007, ovitraps were randomly distributed in the city to collect Ae. aegypti eggs. The variation observed in the number of collected eggs was described by fitting a third-degree polynomial by the least square method, allowing to determine the time when population increase began (week 1), after the temperate and dry season. Eggs were collected throughout the year, with the highest variation in abundance during the warm and rainy season, and the maximum value registered in February 2007. The rate of increase of the number of eggs laid per week peaked between weeks 9 and 10 after the beginning of the population increase (week 1). Week 1 depends on temperature, it occurs after getting over the thermal threshold and the needed accumulation of 160 degree-day is reached. Consequently, week 1 changes depending on temperature. Peak abundance of eggs during 2005-2006 was recorded on week 15 (after week 1); during 2006-2007, the peak was observed on week 22. Estimation of the intrinsic rate of natural increase (r) of Ae. aegypti is useful not only to determine optimal time to apply vector control measures with better cost-benefit, but also to add an insecticide control strategy against the vector to diminish the possibility of resistance. © Copyright 2011, Mary Ann Liebert, Inc. 2011.

Estallo E.L.,National University of Cordoba | Carbajo A.E.,National University of San Martín of Argentina | Grech M.G.,National University of Patagonia San Juan Bosco | Frias-Cespedes M.,Direccion de Epidemiologia | And 4 more authors.
Acta Tropica | Year: 2014

During 2009 the biggest dengue epidemic to date occurred in Argentina, affecting almost half the country. We studied the spatio-temporal dynamics of the outbreak in the second most populated city of the country, Córdoba city. Confirmed cases and the results of an Aedes aegypti monitoring during the outbreak were geolocated. The imported cases began in January, and the autochthonous in March. Thirty-three percent of the 130 confirmed cases were imported, and occurred mainly at the center of the city. The autochthonous cases were more frequent in the outskirts, specially in the NE and SE. Aedes aegypti infestation showed no difference between neighborhoods with or without autochthonous cases, neither between neighborhoods with autochthonous vs. imported cases. The neighborhoods with imported cases presented higher population densities. The majority of autochthonous cases occurred at ages between 25 and 44 years old. Cases formed a spatio-temporal cluster of up to 20 days and 12. km. According to a mathematical model that estimates the required number of days needed for transmission according to daily temperature, the number of cases begun to fall when more than 15.5 days were needed. This may be a coarse estimation of mean mosquito survival in the area, provided that the study area is close to the global distribution limit of the vector, and that cases prevalence was very low. © 2014 Elsevier B.V.

Estallo E.L.,National University of Cordoba | Luduena-Almeida F.F.,National University of Cordoba | Visintin A.M.,National University of Cordoba | Scavuzzo C.M.,Institute Altos Estudios Espaciales Mario Gulich | And 4 more authors.
International Journal of Remote Sensing | Year: 2012

The application of remotely sensed data to public health has increased in Argentina in the past few years, especially to study vector-borne viral diseases such as dengue. The normalized difference vegetation index (NDVI) has been widely used for remote sensing of vegetation as well as the brightness temperature (BT) for many years. Another environmental variable obtained from satellites is the normalized difference water index (NDWI) for remote sensing of the status of the vegetation liquid water from space. The aim of the present article was to test the effectiveness of NDWI together with other satellite and meteorological data to develop two forecasting models, namely the SATMET (satellite and meteorological variables) model and the SAT (satellite environmental variables) model. The models were developed and validated by dividing the data file into two sets: the data between January 2001 and April 2004 were used to construct the models and the data between May 2004 and May 2005 were used to validate them. The regression analysis for the SATMET and SAT models showed an adjusted R 2 of 0.82 and 0.79, respectively. To validate the models, a correlation between the estimates and the observations was obtained for both the SATMET model (r = 0.57) and the SAT model (r = 0.64). Both models showed the same root mean square error (RMSE) of 0.04 and, therefore, the same forecasting power. For this reason, these models may have applications as decision support tools in assisting public health authorities in the control of Aedes aegypti and risk management planning programmes. © 2012 Copyright Taylor and Francis Group, LLC.

Estallo E.L.,National University of Cordoba | Mas G.,Instituto Nacional de Tecnologia Agropecuaria | Vergara-Cid C.,National University of Cordoba | Lanfri M.A.,Institute Altos Estudios Espaciales Mario Gulich | And 5 more authors.
PLoS ONE | Year: 2013

Background: In Argentina, dengue has affected mainly the Northern provinces, including Salta. The objective of this study was to analyze the spatial patterns of high Aedes aegypti oviposition activity in San Ramón de la Nueva Orán, northwestern Argentina. The location of clusters as hot spot areas should help control programs to identify priority areas and allocate their resources more effectively. Methodology: Oviposition activity was detected in Orán City (Salta province) using ovitraps, weekly replaced (October 2005-2007). Spatial autocorrelation was measured with Moran's Index and depicted through cluster maps to identify hot spots. Total egg numbers were spatially interpolated and a classified map with Ae. aegypti high oviposition activity areas was performed. Potential breeding and resting (PBR) sites were geo-referenced. A logistic regression analysis of interpolated egg numbers and PBR location was performed to generate a predictive mapping of mosquito oviposition activity. Principal Findings: Both cluster maps and predictive map were consistent, identifying in central and southern areas of the city high Ae. aegypti oviposition activity. A logistic regression model was successfully developed to predict Ae. aegypti oviposition activity based on distance to PBR sites, with tire dumps having the strongest association with mosquito oviposition activity. A predictive map reflecting probability of oviposition activity was produced. The predictive map delimitated an area of maximum probability of Ae. aegypti oviposition activity in the south of Orán city where tire dumps predominate. The overall fit of the model was acceptable (ROC = 0.77), obtaining 99% of sensitivity and 75.29% of specificity. Conclusions: Distance to tire dumps is inversely associated with high mosquito activity, allowing us to identify hot spots. These methodologies are useful for prevention, surveillance, and control of tropical vector borne diseases and might assist National Health Ministry to focus resources more effectively. © 2013 Estallo et al.

Estallo E.L.,National University of Cordoba | Luduena-Almeida F.,National University of Cordoba | Scavuzzo C.M.,Institute Altos Estudios Espaciales Mario Gulich | Zaidenberg M.,Coordinacion Nacional de Control de Vectores | And 2 more authors.
Revista de Saude Publica | Year: 2011

The study aimed to determinate the maximum daily peak of Aedes aegypti oviposition in the city of Oran, northwestern Argentina. Biweekly samplings were taken between November 2006 and February 2007 (spring-summer). The city was divided into three areas (north, center, and south) and households were randomly selected. Two ovitraps were placed outdoors in the selected houses. Ovitraps were replaced every four hours, from morning (8 a.m.) to late afternoon (8 p.m.). The largest number of eggs was recorded between 4 p.m. and 8 p.m. (81%). These findings enhance our understanding of the vector and thus its control such as spraying during the hours of peak oviposition activity.

Rotela C.H.,Institute Altos Estudios Espaciales Mario Gulich | Spinsanti L.I.,National University of Cordoba | Lamfri M.A.,Institute Altos Estudios Espaciales Mario Gulich | Contigiani M.S.,National University of Cordoba | And 2 more authors.
Geospatial Health | Year: 2011

In response to the first human outbreak (January - May 2005) of Saint Louis encephalitis (SLE) virus in Córdoba province, Argentina, we developed an environmental SLE virus risk map for the capital, i.e. Córdoba city. The aim was to provide a map capable of detecting macro-environmental factors associated with the spatial distribution of SLE cases, based on remotely sensed data and a geographical information system. Vegetation, soil brightness, humidity status, distances to water-bodies and areas covered by vegetation were assessed based on pre-outbreak images provided by the Landsat 5TM satellite. A strong inverse relationship between the number of humans infected by SLEV and distance to high-vigor vegetation was noted. A statistical non-hierarchic decision tree model was constructed, based on environmental variables representing the areas surrounding patient residences. From this point of view, 18% of the city could be classified as being at high risk for SLEV infection, while 34% carried a low risk, or none at all. Taking the whole 2005 epidemic into account, 80% of the cases came from areas classified by the model as medium-high or high risk. Almost 46% of the cases were registered in high-risk areas, while there were no cases (0%) in areas affirmed as risk free.

PubMed | Coordinacion Nacional de Control de Vectores, National University of Tucuman, Institute Altos Estudios Espaciales Mario Gulich and National University of Cordoba
Type: Journal Article | Journal: Journal of vector ecology : journal of the Society for Vector Ecology | Year: 2015

Distribution and abundance of disease vectors are directly related to climatic conditions and environmental changes. Remote sensing data have been used for monitoring environmental conditions influencing spatial patterns of vector-borne diseases. The aim of this study was to analyze the effect of the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS), and climatic factors (temperature, humidity, wind velocity, and accumulated rainfall) on the distribution and abundance of Anopheles species in northwestern Argentina using Poisson regression analyses. Samples were collected from December, 2001 to December, 2005 at three localities, Aguas Blancas, El Oculto and San Ramn de la Nueva Orn. We collected 11,206 adult Anopheles species, with the major abundance observed at El Oculto (59.11%), followed by Aguas Blancas (22.10%) and San Ramn de la Nueva Orn (18.79%). Anopheles pseudopunctipennis was the most abundant species at El Oculto, Anopheles argyritarsis predominated in Aguas Blancas, and Anopheles strodei in San Ramn de la Nueva Orn. Samples were collected throughout the sampling period, with the highest peaks during the spring seasons. LST and mean temperature appear to be the most important variables determining the distribution patterns and major abundance of An. pseudopunctipennis and An. argyritarsis within malarious areas.

Santilli G.,University of Rome La Sapienza | Marzialetti P.,Institute Altos Estudios Espaciales Mario Gulich | Laneve G.,University of Rome La Sapienza
34th International Symposium on Remote Sensing of Environment - The GEOSS Era: Towards Operational Environmental Monitoring | Year: 2011

The large amount of images available today, thanks to the increasing of the number of orbiting EO satellites (Earth Observation Systems), which are able to provide information of every region of the Earth, represents an indispensable instrument for monitoring any terrestrial ecosystem. EO systems allow to detect and follow fast changing phenomena (like natural and anthropic disasters) providing the needed information for planning the necessary measures and reduce the impact of these events. This paper aims at showing the results obtained through the transformation of Mathematical Morphology algorithms (which have already shown their effectiveness) in IDL based algorithms (using ENVI EX rule sets) that can provide identical performances. The direct execution of these algorithms in a GIS environment, taking into account topology restrictions, allows to directly generate maps containing potential oil spills isolated on satellite images (exploiting the geometrical and physical characteristics of oil spills) together with contextual information on the same maps (typical of the GIS environment, as the wind regime, presence of vessels, etc) in order to assign a probability to candidate spots and create a much more accurate oil spill detection process.

The theoretical formulation of the Green-Ampt infiltration model has been extended to conditions of decreasing flooding depth in an isolated system. By defining dimensionless variables of flooding depth s and time τ, an implicit dimensionless equation τ(s) was obtained, which contains a single fundamental dimensionless parameter γ controlling the process, named "infiltration delay parameter". The characteristics and functional behaviour of γ were analysed, and its physical meaning discussed. A parametric expression s(τ) has been obtained, which uses a unique descriptive parameter a, which in turn depends only on γ and on four generic coefficients valid for a wide range of soil properties and conditions occurring in nature. By means of numerical simulations using different values of soil parameters and initial flooding depths, it was proved that the proposed parametric function generates similar infiltration rates and cumulative storages to those that are obtained starting from Darcy's equation in the extended Green-Ampt scheme. © 2011 Copyright IAHS Press.

Carmona F.,National University of Central Buenos Aires | Carmona F.,CONICET | Rivas R.,National University of Central Buenos Aires | Fonnegra D.C.,Institute Altos Estudios Espaciales Mario Gulich
European Journal of Remote Sensing | Year: 2015

Normalized Area Vegetation Index (NAVI) is proposed for estimating chlorophyll content (Chl) from remote sensing data. NAVI is obtained using only two bands on red and near infrared regions of the spectrum. It is derived from the hyperspectral NAOC index, which was initially developed for the Chl mapping. For determining the relationship between NAOC and NAVI we used 257 spectra obtained with the Proba/CHRIS sensor during the SPARC-2003/2004 campaigns in Barrax, Spain. NAVI was estimated with different pairs of bands and a correlation matrix with NAOC index was obtained. Results show very good linear correlation coefficients, with values ≥ 0.97. NAVI allows to estimate leaf Chl from satellite data with medium spectral resolution. © 2015, Associazione Italiana di Telerilevamento. All rights reserved.

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