12 results on '"Gorla, David E."'
Search Results
2. Rural houses infestation by Triatoma infestans in northwestern Argentina: Vector control in a high spatial heterogeneous infestation area.
- Author
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Cavallo, María José, Amelotti, Ivana, Abrahan, Luciana, Cueto, Gerardo, and Gorla, David E.
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TRIATOMA infestans ,TRIATOMA ,HEMIPTERA ,TRYPANOSOMA ,PARASITES ,PHYSIOLOGY - Abstract
Triatoma infestans (Hemiptera: Reduviidae) is a vector of the Trypanosoma cruzi parasite, causative agent of Chagas disease. During the last decade, vector control activities have been systematically carried out in northwestern Argentina, an endemic region for this disease. The general aim of this study to evaluate was spatio-temporal variation of infestation by T. infestans in rural communities of Los Llanos in La Rioja province. We estimated house infestation using two sampling methods: passive and active. Passive collection was conducted with community participation collecting triatomines. Six passive collections were carried out in 397 houses during the warm season between 2014 and 2017. Active collection of T. infestans was thoroughly performed by trained staff for 60 minutes and was carried out once in March 2016. The estimate of intradomestic infestation did not show significant differences between both collection methods (p = 0.39). However, passive collection method had lower sensitivity than active collection method for the estimation of peridomestic infestation and intradomestic colonization (PDI: p< 0.01; ID colonization: p< 0.01). The results obtained with passive collection methods showed that the infestation in the study area was spatially heterogeneous and temporally variable. Intradomiciliary infestation decreased over time (14.4% to 7.9%, p<0.05) although the effect of the chemical treatment application was not associated with the infestation level of T. infestans (p = 0.15) and the Departments had a different response each year (p<0.01). A high infestation cluster was located in the south of our study area during 2016–2017. The vector presence in the houses confirms the importance of to improve entomological surveillance programs. The search for triatomines carried out by the inhabitants might be a useful method to complement the activities of vector control programs in isolated and rural areas. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
3. Does nutrition influence sexual dimorphism in Triatoma infestans (Hemiptera: Reduviidae) of natural habitats?
- Author
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HERNÁNDEZ, María L., AMELOTTI, Ivana, CATALÁ, Silvia, and GORLA, David E.
- Subjects
TRIATOMA infestans ,SEXUAL dimorphism ,ASSASSIN bugs ,CONENOSES ,CHAGAS' disease ,PARASITES - Abstract
Copyright of Revista de la Sociedad Entomológica Argentina is the property of Sociedad Entomologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2018
- Full Text
- View/download PDF
4. Spatial and temporal distribution of house infestation by Triatoma infestans in the Toro Toro municipality, Potosi, Bolivia.
- Author
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Echeverria, Jorge Espinoza, Rodriguez, Antonio Nogales, Cortez, Mirko Rojas, Diotaiuti, Liléia Gonçalves, and Gorla, David E.
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TICK infestations ,TRIATOMA ,HETEROGENEITY ,MUNICIPAL government ,VECTOR control - Abstract
Background: Triatoma infestans is the main vector of Trypanosoma cruzi in Bolivia. The species is present both in domestic and peridomestic structures of rural areas, and in wild ecotopes of the Andean valleys and the Great Chaco. The identification of areas persistently showing low and high house infestation by the vector is important for the management of vector control programs. This study aimed at analyzing the temporal and spatial distribution of house infestation by T. infestans in the Toro Toro municipality (Potosi, Bolivia) between 2009 and 2014, and its association with environmental variables. Methods: House infestation and T. infestans density were calculated from entomological surveys of houses in the study area, using a fixed-time effort sampling technique. The spatial heterogeneity of house infestation was evaluated using the SatScan statistic. Association between house infestation with Bioclim variables (Worldclim database) and altitude was analyzed using a generalized linear model (GLM) with a logit link. Model selection was based on the Akaike information criteria after eliminating collinearity between variables using the variable inflation factor. The final model was used to create a probability map of house infestation for the Toro Toro municipality. Results: A total of 73 communities and 16,489 house evaluation events were analyzed. Presence of T. infestans was recorded on 480 house evaluation events, giving an overall annual infestation of 2.9% during the studied period (range 1.5-5.4% in 2009 and 2012). Vector density remained at about 1.25 insects/house. Infestation was highly aggregated in five clusters, including 11 communities. Relative risk of infestation within these clusters was 1.7-3.9 times the value for the regional average. Four environmental variables were identified as good descriptors of house infestation, explaining 57% of house infestation variability. The model allowed the estimation of a house infestation surface for the Toro Toro municipality. Conclusion: This study shows that residual and persistent populations of T. infestans maintain low house infestation, representing a potential risk for the transmission of T. cruzi in these communities, and it is possible to stratify house infestation using EV, and produce a risk map to guide the activities of vector control interventions in the municipality of Toro Toro (Potosi, Bolivia). [ABSTRACT FROM AUTHOR]
- Published
- 2017
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- View/download PDF
5. Remotely sensed environmental variables as indicators of Triatoma infestans (Heteroptera: Reduviidae) distribution
- Author
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Gorla, David E.
- Subjects
sensores remotos ,Chagas disease ,remote sensing ,enfermedad de Chagas ,distribución geográfica ,geographic distribution ,Triatoma infestans - Abstract
El trabajo presenta un análisis de la distribución geográfica de Triatoma infestans basado en variables biofísicas calculadas a partir de datos obtenidos por satélites meteorológicos. Se consideran datos derivados de un Análisis Temporal de Fourier sobre imágenes mensuales que contienen un conjunto de 14 descriptores estadísticos del promedio, mínimo, máximo, variabilidad, amplitud y fase de la temperatura del aire, la temperatura de superficie, la radiación infrarroja media y el índice de vegetación calculados con datos colectados por el sensor AVHRR. La serie temporal considerada cubre el período 1982.2000 y el área abarca desde Panamá hasta Tierra del Fuego. El análisis de variables individuales mostró que la fase anual del índice de vegetación identifica correctamente el 80% de los sitios donde Triatoma infestans está presente y ausente. El análisis confirmó la importancia de la temperatura (especialmente la del aire) sobre la distribución de Triatoma infestans, ya que 7 descriptores estadísticos de la temperatura del aire (de un total de 14) identificaron correctamente >70% de los sitios donde Triatoma infestans está ausente y presente. Un Análisis Lineal Discriminante por Pasos mostró que una función con seis descriptores estadísticos (cuatro asociados con la temperatura del aire, uno con la radiación infrarroja media y uno con el índice de vegetación) identificaron correctamente el 90% de los sitios donde Triatoma infestans está presente y ausente. El análisis muestra la importante asociación entre las variables estudiadas a escala continental y la distribución de una especie doméstica y hematófaga. El enfoque de trabajo puede resultar de utilidad en estudios de escala geográfica amplia sobre la distribución de otras especies con una relación más directa y causal con la vegetación y el clima que Triatoma infestans. The paper presents an analysis of the geographic distribution of Triatoma infestans based on biophysical variables recorded by meteorological satellites. The analysis includes data derived from a temporal Fourier Analysis of monthly images over a set of 14 derived statistical descriptors of the average, minimum, maximum, variability, amplitude and phase of the air temperature, land surface temperature, medium infrared radiation and a vegetation index remotely sensed by the AVHRR. Temporal series covered the period 1982.2000, and the area from Panamá to Tierra del Fuego. The analysis of individual variables showed that the annual phase of the normalised difference vegetation index identifies correctly 80% presence and absence sites of Triatoma infestans. The analysis confirms the importance of temperature (especially air temperature) for Triatoma infestans distribution, as 7 (out of 14) statistical descriptors associated with air temperature identified correctly >70% of presence and absence sites. A Stepwise Linear Discriminant Analysis showed that a function with six statistical descriptors (four of them associated with air temperature, one associated with medium infrared radiation, and one with the vegetation index) identified correctly 90% of presence and absence sites of Triatoma infestans. The analysis shows the important association between the environmental variables studied at the continental scale and the distribution of a strictly domestic and haematophagous species. The approach could be useful for large scale studies of the distribution of other species with more direct and causal relation with vegetation and climate than Triatoma infestans.
- Published
- 2002
6. Distribution of Pyrethroid Resistant Populations of Triatoma infestans in the Southern Cone of South America.
- Author
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Bustamante Gomez, Marinely, Gonçalves Diotaiuti, Liléia, and Gorla, David E.
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PYRETHROIDS ,TRIATOMA infestans ,INSECTICIDES ,LINEAR statistical models ,MATHEMATICAL models ,CYTOGENETICS - Abstract
Background: A number of studies published during the last 15 years showed the occurrence of insecticide resistance in Triatoma infestans populations. The different toxicological profiles and mechanisms of resistance to insecticides is due to a genetic base and environmental factors, being the insecticide selective pressure the best studied among the last factors. The studies on insecticide resistance on T. infestans did not consider the effect of environmental factors that may influence the distribution of resistance to pyrethroid insecticides. To fill this knowledge gap, the present study aims at studying the association between the spatial distribution of pyrethroid resistant populations of T. infestans and environmental variables. Methodology/Principal Findings: A total of 24 articles reporting on studies that evaluated the susceptibility to pyrethroids of 222 field-collected T. infestans populations were compiled. The relationship between resistance occurrence (according to different criteria) with environmental variables was studied using a generalized linear model. The lethal dose that kills 50% of the evaluated population (LD
50 ) showed a strong linear relationship with the corresponding resistance ratio (RR50 ). The statistical descriptive analysis of showed that the frequency distribution of the Log (LD50 ) is bimodal, suggesting the existence of two statistical groups. A significant model including 5 environmental variables shows the geographic distribution of high and low LD50 groups with a particular concentration of the highest LD50 populations over the region identified as the putative center of dispersion of T. infestans. Conclusions/Significance: The occurrence of these two groups concentrated over a particular region that coincides with the area where populations of the intermediate cytogenetic group were found might reflect the spatial heterogeneity of the genetic variability of T. infestans, that seems to be the cause of the insecticide resistance in the area, even on sylvatic populations of T. infestans, never before exposed to pyrethroid insecticides, representing natural and wild toxicological phenotypes. The strong linear relationship found between LD50 and RR50 suggest RR50 might not be the best indicator of insecticide resistance in triatomines. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
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7. Primer registro de Triatoma infestans (Klug) (Hemiptera: Reduviidae) asociado a nidos de loros barranqueros (Cyanoliseus patagonus) (Aves: Psittacidae).
- Author
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HERNÁNDEZ, María L., AMELOTTI, Ivana, LÓPEZ, Pablo, ABRAHAN, Luciana B., GORLA, David E., and CATALÁ, Silvia S.
- Subjects
TRIATOMA infestans ,TRIATOMA ,CYANOLISEUS patagonus ,CONENOSES ,CHAGAS' disease ,DISEASE vectors - Abstract
Copyright of Revista de la Sociedad Entomológica Argentina is the property of Sociedad Entomologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
8. Phenotypic Variability and Population Structure of Peridomestic Triatoma infestans in Rural Areas of the Arid Chaco (Western Argentina): Spatial Influence of Macro- and Microhabitats.
- Author
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Hernández, María Laura, Abrahan, Luciana Beatriz, Dujardin, Jean Pierre, Gorla, David E., and Catalá, Silvia S.
- Subjects
PHENOTYPES ,TRIATOMA ,TRYPANOSOMA cruzi ,ARTHROPOD vectors ,INVERTEBRATES as carriers of disease - Abstract
Triatoma infestans, one of the main vectors of Trypanosoma cruzi, is strongly associated with rural human ecotopes. Infested peridomestic places could act as a source of house infestation as a result of the movement of vectors among habitats. The quantitative study of phenotypic traits and nutritional variables could be informative about the population structure and the relative mobility of vectors. This is the first approach toward analyzing the phenetic characteristics of T. infestans and the relationship with their potential role to invade and colonize other habitats in the arid Chaco region. This article compares the phenotypic structure of T. infestans populations living in chicken coops and goat corrals, analyzing the geometric morphometry of wings and heads, antennal phenotypes, and the nutritional status of 257 adults and nymphs. The study area remained untreated with insecticides during the 15 years before the present study. The insects collected in peridomestic structures located in two zones 80 km apart exhibited significant differences in their morphotypes, suggesting an environmental effect and/or the absence of individual exchange between zones. The population structure was clear in T. infestans from goat corrals and chicken coops in one zone and less pronounced in the other. These results suggest the existence of a different rate of individual exchange among ecotopes within each zone. Morphometric variables of heads and wings were significantly correlated in insects collected in goat corrals but not in chicken coops, suggesting a habitat effect and supporting the hypothesis of different canalization forces that affect the two organs. The nutritional status of adults indicated a low dispersal probability with zonal differences. This article provides the first combined morphometric analysis of the head of adults and fifth instar nymphs in triatomines and the first combined analysis of head and wing in T. infestans. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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9. Variability of the Susceptibility to Deltamethrin in Triatoma infestans: The Female Factor
- Author
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Amelotti, Ivana, Romero, Nahuel, Catalá, Silvia S., and Gorla, David E.
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- 2011
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10. The Effects of Cypermethrin Pour-On and Piperonyl Butoxide on Triatoma infestans Under Laboratory Conditions
- Author
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Amelotti, Ivana, Catalá, Silvia S., and Gorla, David E.
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- 2010
- Full Text
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11. Seroprevalence of Trypanosoma cruzi infection and vector control activities in rural communities of the southern Gran Chaco (Argentina)
- Author
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Moreno, Mariana Laura, Moretti, Edgardo, Basso, Beatriz, Céspedes, Maria Frias, Catalá, Silvia S., and Gorla, David E.
- Subjects
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SEROPREVALENCE , *TRYPANOSOMA cruzi , *VECTOR control , *PROTOZOAN diseases , *RURAL population , *CHAGAS' disease , *TRIATOMA - Abstract
Abstract: We compared age-related seroprevalence of Trypanosoma cruzi infection with history of vector control interventions and social and ecological changes in three historically endemic departments of Cordoba province, Argentina, covering an area of 42,600km2 of the Gran Chaco region. Using a cross sectional design, blood samples of 5240 people between 6 months and 40 years of age, living in 192 rural communities were analyzed to detect T. cruzi infection using ELISA tests, and confirmed with indirect immunofluorescent antibody test and indirect haemoagglutination. Overall seroprevalence was 5.4%, 7.9% and 7.5% in the north, northwest and west studied areas (average for all areas 6.95%). Seroprevalence for T cruzi increased with population age, especially in age classes older than 15 years of age. Communities of the north and west areas showed 0.59% seroprevalence for T. cruzi in children below 15 years of age, whereas children of the same age in the northwest region showed a seroprevalence of 3.08%. Comparative analyses indicate that vector control activities and land use changes during the last decades are the most likely causes of the overall reduction of T. cruzi prevalence. Results suggest that the vectorial transmission of T. cruzi has been strongly reduced and probably interrupted in the north and west areas, but it is still active in the northwestern rural settlements of Córdoba province. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
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12. Triatominae of the semi-arid Chaco in central Argentina.
- Author
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Cardozo, Miriam, Fiad, Federico G., Crocco, Liliana B., and Gorla, David E.
- Subjects
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CONENOSES , *CHAGAS' disease , *DISEASE vectors , *NUMBERS of species , *TRIATOMA - Abstract
• Seven Triatominae species were reported invading houses in central Argentina. • T. guasayana and T. garciabesi were the most frequent species invading domiciles. • Peridomestic populations of T. infestans continue to be a challenge for vector control programs. • First record, in the study area, of a nymph of T. infestans captured in the wild environment. The epidemiological scenario in central Argentinian Chaco region shows persistence of Triatoma infestans domestic populations in endemic areas, with control interventions historically affected by the economic instability of the region. Considering this situation, we aimed to (i) update the information regarding to the diversity of triatomines present in domestic, peridomestic and sylvatic environments in departments historically endemic of the Chaco region, (ii) to report the occurrence of secondary vectors of Chagas disease invading domestic environments and (iii) to discuss the possible sources of dispersal of these sylvatic species towards anthropic habitats. Between November 2017 and March 2020, we visited fourteen rural communities of northwest Córdoba province (central Argentina). Entomological data were collected through community vector surveillance in domiciles, active search in peridomiciles and the use of light and yeast traps in sylvatic environments. Seven Triatominae species were captured invading domiciles (T. guasayana, T. garciabesi, T. platensis, T. delpontei, T. breyeri, Panstrongylus guentheri and T. infestans). T. guasayana and T. garciabesi were the species with the highest number of captures. The 32% of the peridomiciles registered infestation with T. infestans (n = 355), mostly in chicken coops and goat pens. In sylvatic environments, T. garciabesi, T. guasayana, T. infestans and P. guentheri were collected. Only one adult specimen of T. infestans was positive for the presence of Trypanosoma cruzi. Our results suggest that the persistence of T. infestans populations in peridomiciles continues to be a serious challenge for control programs, whereas the finding of secondary vectors of Chagas disease actively invading domiciles emphasizes the need to implement new strategies for entomological surveillance. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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