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Francois Noireau - One of the best experts on this subject based on the ideXlab platform.
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New Discoveries of Sylvatic Triatoma Infestans (Hemiptera: Reduviidae) Throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Rosio Buitrago, Francois Noireau, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T. Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi TcI; one T. Infestans was infected with TcII. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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New discoveries of sylvatic Triatoma Infestans (Hemiptera : Reduviidae) throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Francois Noireau, Rocio Buitrago, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi Tcl; one T. Infestans was infected with Tell. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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Genetic characterization of Trypanosoma cruzi DTUs in wild Triatoma Infestans from Bolivia : predominance of TcI
PLoS Neglected Tropical Diseases, 2012Co-Authors: Simone Frederique Breniere, Etienne Waleckx, Claudia Aliaga, Rocio Buitrago, Christian Barnabe, Michel Tibayrenc, R. Salas, Francois NoireauAbstract:Background: The current persistence of Triatoma Infestans (one of the main vectors of Chagas disease) in some domestic areas could be related to re-colonization by wild populations which are increasingly reported. However, the infection rate and the genetic characterization of the Trypanosoma cruzi strains infecting these populations are very limited. Methodology/Principal Findings: Of 333 wild Triatoma Infestans specimens collected from north to south of a Chagas disease endemic area in Bolivia, we characterized 234 stocks of Trypanosoma cruzi using mini-exon multiplex PCR (MMPCR) and sequencing the glucose phosphate isomerase (Gpi) gene. Of the six genetic lineages ("discrete typing units"; DTU) (TcI-VI) presently recognized in T. cruzi, TcI (99.1%) was overdominant on TcIII (0.9%) in wild Andean T. Infestans, which presented a 71.7% infection rate as evaluated by microscopy. In the lowlands (Bolivian Chaco), 17 "dark morph" T. Infestans were analyzed. None of them were positive for parasites after microscopic examination, although one TcI stock and one TcII stock were identified using MMPCR and sequencing. Conclusions/Significance: By exploring large-scale DTUs that infect the wild populations of T. Infestans, this study opens the discussion on the origin of TcI and TcV DTUs that are predominant in domestic Bolivian cycles.
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Susceptibility of sylvatic Triatoma Infestans from Andeans valleys of Bolivia to deltamethrin and fipronil
Journal of Medical Entomology, 2011Co-Authors: G. R. Acevedo, Francois Noireau, Mirko Cortez, G. M. Cueto, M. Germano, P. S. Orihuela, M. I. Picollo, C. VassenaAbstract:We describe the susceptibility to deltamethrin and fipronil of four sylvatic Triatoma Infestans populations from the Andean valleys of Bolivia. Fifty percent lethal doses were determined from topical application of insecticide on first instars, and mortality was assessed after 24 h for deltamethrin and 48 h for fipronil. In comparison with a reference strain from Argentina, the Bolivian populations showed deltamethrin 50 percent lethal dose ratios ranging from 1.9 to 17.4. In the case of fipronil, an insecticide never used for control of T. Infestans, the Bolivian populations showed even higher variation in toxic response, with relative susceptibilities ranging from 0.5 to 139.2. However, although the sylvatic T. Infestans toxicological profiles differ from each other and from those of the domiciliary population studied in this work, there were no significant differences in the activities of P450 mono-oxygenases and pyrethroid esterases between the reference strain and the studied populations.
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First report of widespread wild populations of Triatoma Infestans (Reduviidae, Triatominae) in the valleys of La Paz, Bolivia
American Journal of Tropical Medicine and Hygiene, 2010Co-Authors: Rocio Buitrago, Etienne Waleckx, Renata Salas, Francois Noireau, Marie-france Bosseno, F. Zoveda, Pablo Vidaurre, E. Mamani, Simone Frederique BreniereAbstract:Wild populations of Triatoma Infestans, the main vector of Chagas disease in the Southern Cone countries, may be involved in reinfestation of human dwellings, limiting the success of vector-control campaigns in Bolivia. Knowledge of the distribution of these populations remains incomplete. We report here the detection of T Infestans wild populations in large areas in the department of La Paz, Bolivia. Among 18 sylvatic areas investigated, 17 were positive with T Infestans specimens. The infection rate of captured T Infestans with Trypanosoma cruzi was 85.7% in adult specimens. These results expand the geographical distribution of wild populations of T. Infestans; it may be distributed throughout the Inter-Andean Dry Forest eco-region of Bolivia. The current information allows us to propose the hypothesis that a sylvatic origin of the reinfestation is located in the valleys of La Paz.
Simone Frederique Breniere - One of the best experts on this subject based on the ideXlab platform.
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Risk of transmission of Trypanosoma cruzi by wild Triatoma Infestans (Hemiptera : Reduviidae) in Bolivia supported by the detection of human blood meals
Infection Genetics and Evolution, 2013Co-Authors: N. L. R. Buitrago, Etienne Waleckx, Marie-france Bosseno, Philippe Brémond, P. Vidaurre, F. Zoveda, Simone Frederique BreniereAbstract:We analyzed the food sources of Bolivian wild Triatoma Infestans (the main vector of Chagas disease in this country), to assess the role of these populations in the epidemiological context of Chagas disease. Ninety-eight blood meals were identified by heteroduplex assay and sequencing. Most of them were from wild mammals but surprisingly 27 were from humans. This brings to light the occurrence of human-vector contacts at risk of Trypanosoma cruzi transmission in the wild environment by highly infected insects.
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New Discoveries of Sylvatic Triatoma Infestans (Hemiptera: Reduviidae) Throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Rosio Buitrago, Francois Noireau, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T. Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi TcI; one T. Infestans was infected with TcII. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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New discoveries of sylvatic Triatoma Infestans (Hemiptera : Reduviidae) throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Francois Noireau, Rocio Buitrago, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi Tcl; one T. Infestans was infected with Tell. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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Genetic characterization of Trypanosoma cruzi DTUs in wild Triatoma Infestans from Bolivia : predominance of TcI
PLoS Neglected Tropical Diseases, 2012Co-Authors: Simone Frederique Breniere, Etienne Waleckx, Claudia Aliaga, Rocio Buitrago, Christian Barnabe, Michel Tibayrenc, R. Salas, Francois NoireauAbstract:Background: The current persistence of Triatoma Infestans (one of the main vectors of Chagas disease) in some domestic areas could be related to re-colonization by wild populations which are increasingly reported. However, the infection rate and the genetic characterization of the Trypanosoma cruzi strains infecting these populations are very limited. Methodology/Principal Findings: Of 333 wild Triatoma Infestans specimens collected from north to south of a Chagas disease endemic area in Bolivia, we characterized 234 stocks of Trypanosoma cruzi using mini-exon multiplex PCR (MMPCR) and sequencing the glucose phosphate isomerase (Gpi) gene. Of the six genetic lineages ("discrete typing units"; DTU) (TcI-VI) presently recognized in T. cruzi, TcI (99.1%) was overdominant on TcIII (0.9%) in wild Andean T. Infestans, which presented a 71.7% infection rate as evaluated by microscopy. In the lowlands (Bolivian Chaco), 17 "dark morph" T. Infestans were analyzed. None of them were positive for parasites after microscopic examination, although one TcI stock and one TcII stock were identified using MMPCR and sequencing. Conclusions/Significance: By exploring large-scale DTUs that infect the wild populations of T. Infestans, this study opens the discussion on the origin of TcI and TcV DTUs that are predominant in domestic Bolivian cycles.
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Susceptibility and resistance to deltamethrin of wild and domestic populations of Triatoma Infestans (Reduviidae : Triatominae) in Bolivia : new discoveries
Memórias do Instituto Oswaldo Cruz., 2012Co-Authors: Stéphanie Depickère, Etienne Waleckx, Marcelo Monje, Rocio Buitrago, Edda Sinani, M. Baune, Ronald Lopez, Tamara Chavez, Simone Frederique BreniereAbstract:Bolivia is a high-endemic country for Chagas disease, for which the principal vector is Triatoma Infestans (Triatominae). This is a mainly domestic species that is also found in the wild environment. Recently, an increasing number of studies have shown the importance of Triatominae resistance to insecticides, especially in Bolivia. Data regarding the susceptibility/resistance of wild and domestic populations of T. Infestans to deltamethrin are presented. For the first time, domestic populations of the department of Santa Cruz were tested, showing low resistance. Although most of the wild populations were found to be susceptible to deltamethrin, three populations from three departments showed a mortality rate of less than 100%. This result is emphasised here.
Jean-pierre Dujardin - One of the best experts on this subject based on the ideXlab platform.
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spatial structuring of Triatoma Infestans hemiptera reduviidae populations from northwestern argentina using wing geometric morphometry
Journal of Medical Entomology, 2004Co-Authors: Judith Schachterbroide, Jean-pierre Dujardin, Uriel Kitron, Ricardo E GurtlerAbstract:Wing geometric morphometry was used to study the spatial structuring of populations of Triatoma Infestans from different villages, ecotopes, and sites within a village in northwestern Argentina. A total of 308 male and 197 female wings of T. Infestans collected from peridomestic and domestic ecotopes in March 2000 was analyzed. On average, female bugs had a significantly larger wing size than males. Triatomines collected from domiciles or structures associated with chickens had larger wings than bugs collected from goat or pig corrals. The wing size of bugs did not differ significantly between villages. Discriminant analyses of wing shape showed significant divergence between villages, ecotopes, and individual collection sites. The study of metric variation of males between sites belonging to the same ecotope also revealed significant heterogeneity. Indeed, within the same section of the village the difference between two goat corrals was sometimes greater than that between neighboring goat and pig corrals. Thus, morphometric heterogeneity within villages may be the result not only of ecotope and host associations, but also of physical isolation between subunits. The strong structuring of T. Infestans populations in the study area indicates that recolonization could be traced back to a small geographic source.
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wing geometry in Triatoma Infestans klug and t melanosoma martinez olmedo carcavallo hemiptera reduviidae
Systematic Entomology, 2003Co-Authors: M Gumiel, Francois Noireau, Silvia Catala, Rojas A De Arias, A Garcia, Jean-pierre DujardinAbstract:Abstract. Geometric morphometrics is a novel approach to biological shape analysis, and its application to medical entomology is just beginning. Here, we use it to examine geographical and interspecific variation in the Triatoma Infestans complex, vectors of Chagas disease in southern Latin America. Using six landmarks defining the membranous part of the hemelytra, we analysed the geographical patterns of variation in several populations of T. Infestans, including the recently described ‘dark morph’ of T. Infestans from hollow trees in the Bolivian Chaco. As a potential outgroup, T. melanosoma was added to the sample. A consistent geographical differentiation was observed, but no evidence was found in either sex to consider either the dark morph or T. melanosoma as a species distinct from T. Infestans. Triatoma melanosoma is relegated to synonymy with T. Infestans (syn.n.).
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Mitochondrial DNA variation of Triatoma Infestans populations and its implication on the specific status of T. melanosoma
Memórias do Instituto Oswaldo Cruz., 1999Co-Authors: F.a. Monteiro, Francois Noireau, Jean-pierre Dujardin, R. Pérez, F. Panzera, C. Galvao, D. Rocha, C. Schofield, C.b. BeardAbstract:DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical #Triatoma Infestans$ populations and their phylogenetic relationship with #T. melanosoma$ and #T. brasiliensis$. #T. Infestans$ and #T. melanosoma$ were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. #T. Infestans$ populations presented four haplotypes that could be separated in two clusters : one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic #T. Infestans$ populations from Bolivia (Andes) were genetically identical. (Résumé d'auteur)
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Mitochondrial DNA variation of Triatoma Infestans populations and its implication on the specific status of T. melanosoma
Memórias do Instituto Oswaldo Cruz., 1999Co-Authors: F.a. Monteiro, Francois Noireau, Jean-pierre Dujardin, R. Pérez, F. Panzera, C. Galvao, D. Rocha, C. Schofield, C.b. BeardAbstract:DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical Triatoma Infestans populations and their phylogenetic relationship with T. melanosoma and T. brasiliensis. T. Infestans and T. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. T. Infestans populations presented four haplotypes that could be separated in two clusters: one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic T. Infestans populations from Bolivia (Andes) were genetically identical.
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Population structure of Andean Triatoma Infestans : allozyme frequencies and their epidemiological relevance
Medical and Veterinary Entomology, 1998Co-Authors: Jean-pierre Dujardin, C J Schofield, Michel TibayrencAbstract:#Triatoma Infestans$ (#Hemiptera$ : #Reduviidae$) from 22 Andean localities in Bolivia (n=968) and Peru (n=37) were analysed by multi-locus enzyme electrophoresis. Among 12 gene-enzyme systems analysed, GPD, 6GPD and PCM were polymorphic, ACON, G6PD, GPI, IDH, LAP, MDH, ME, PEP-A and PEP-B were monomorphic. Allozyme frequencies were analysed in relation to geographical and climatic factors, and the presence or absence of #Trypanosoma cruzi$ infection. At one locality (Vallegrande, Bolivia), the frequency of 6Pgd-1 was significantly higher in infected (41% of 85) than in uninfected (17% of 83) adult #T. Infestans$, although no such difference was found among nymphs (n=347). From other localities, only insects infected with #T. cruzi$ were subjected to isosyme analysis. Populations of #T. Infestans$ within villages showed panmixia, while genetic differenciation of #T. Infestans$ between villages was correlated with the distance between them. The genetic structure of #T. Infestans$ natural populations followed an "isolation by distance" model, involving a series of founder effects followed by genetic drift, rather than adaptation in response to differential selection pressures. This conforms with circumstantial evidence that #T. Infestans$ spread, mainly in association with recent human migrations, from a source, probably in southern Bolivia. Isoenzyme characterization of populations of #T. Infestans$ could be used to infer sources of re-infestation during the surveillance phase of control programs. (Résumé d'auteur)
Etienne Waleckx - One of the best experts on this subject based on the ideXlab platform.
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Risk of transmission of Trypanosoma cruzi by wild Triatoma Infestans (Hemiptera : Reduviidae) in Bolivia supported by the detection of human blood meals
Infection Genetics and Evolution, 2013Co-Authors: N. L. R. Buitrago, Etienne Waleckx, Marie-france Bosseno, Philippe Brémond, P. Vidaurre, F. Zoveda, Simone Frederique BreniereAbstract:We analyzed the food sources of Bolivian wild Triatoma Infestans (the main vector of Chagas disease in this country), to assess the role of these populations in the epidemiological context of Chagas disease. Ninety-eight blood meals were identified by heteroduplex assay and sequencing. Most of them were from wild mammals but surprisingly 27 were from humans. This brings to light the occurrence of human-vector contacts at risk of Trypanosoma cruzi transmission in the wild environment by highly infected insects.
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New Discoveries of Sylvatic Triatoma Infestans (Hemiptera: Reduviidae) Throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Rosio Buitrago, Francois Noireau, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T. Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi TcI; one T. Infestans was infected with TcII. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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New discoveries of sylvatic Triatoma Infestans (Hemiptera : Reduviidae) throughout the Bolivian Chaco
American Journal of Tropical Medicine and Hygiene, 2012Co-Authors: Etienne Waleckx, Stéphanie Depickère, Renata Salas, Claudia Aliaga, Marcelo Monje, Hiber Calle, Francois Noireau, Rocio Buitrago, Simone Frederique BreniereAbstract:Sylvatic populations of Triatoma Infestans might be involved in the recolonization of human dwellings. We report here the discoveries of new T Infestans sylvatic foci in the Bolivian Chaco. Eighty-one triatomines were caught, 38 of which were identified as T. Infestans. Triatoma sordida and Panstrongylus geniculatus were the other species collected. One T. Infestans and one T. sordida were infected with Trypanosoma cruzi Tcl; one T. Infestans was infected with Tell. These discoveries add to the debate on the geographic distribution of sylvatic T. Infestans populations, the geographic origin of the species, and the epidemiological role of these populations.
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Genetic characterization of Trypanosoma cruzi DTUs in wild Triatoma Infestans from Bolivia : predominance of TcI
PLoS Neglected Tropical Diseases, 2012Co-Authors: Simone Frederique Breniere, Etienne Waleckx, Claudia Aliaga, Rocio Buitrago, Christian Barnabe, Michel Tibayrenc, R. Salas, Francois NoireauAbstract:Background: The current persistence of Triatoma Infestans (one of the main vectors of Chagas disease) in some domestic areas could be related to re-colonization by wild populations which are increasingly reported. However, the infection rate and the genetic characterization of the Trypanosoma cruzi strains infecting these populations are very limited. Methodology/Principal Findings: Of 333 wild Triatoma Infestans specimens collected from north to south of a Chagas disease endemic area in Bolivia, we characterized 234 stocks of Trypanosoma cruzi using mini-exon multiplex PCR (MMPCR) and sequencing the glucose phosphate isomerase (Gpi) gene. Of the six genetic lineages ("discrete typing units"; DTU) (TcI-VI) presently recognized in T. cruzi, TcI (99.1%) was overdominant on TcIII (0.9%) in wild Andean T. Infestans, which presented a 71.7% infection rate as evaluated by microscopy. In the lowlands (Bolivian Chaco), 17 "dark morph" T. Infestans were analyzed. None of them were positive for parasites after microscopic examination, although one TcI stock and one TcII stock were identified using MMPCR and sequencing. Conclusions/Significance: By exploring large-scale DTUs that infect the wild populations of T. Infestans, this study opens the discussion on the origin of TcI and TcV DTUs that are predominant in domestic Bolivian cycles.
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Susceptibility and resistance to deltamethrin of wild and domestic populations of Triatoma Infestans (Reduviidae : Triatominae) in Bolivia : new discoveries
Memórias do Instituto Oswaldo Cruz., 2012Co-Authors: Stéphanie Depickère, Etienne Waleckx, Marcelo Monje, Rocio Buitrago, Edda Sinani, M. Baune, Ronald Lopez, Tamara Chavez, Simone Frederique BreniereAbstract:Bolivia is a high-endemic country for Chagas disease, for which the principal vector is Triatoma Infestans (Triatominae). This is a mainly domestic species that is also found in the wild environment. Recently, an increasing number of studies have shown the importance of Triatominae resistance to insecticides, especially in Bolivia. Data regarding the susceptibility/resistance of wild and domestic populations of T. Infestans to deltamethrin are presented. For the first time, domestic populations of the department of Santa Cruz were tested, showing low resistance. Although most of the wild populations were found to be susceptible to deltamethrin, three populations from three departments showed a mortality rate of less than 100%. This result is emphasised here.
Ricardo E Gurtler - One of the best experts on this subject based on the ideXlab platform.
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factors affecting infestation by Triatoma Infestans in a rural area of the humid chaco in argentina a multi model inference approach
PLOS Neglected Tropical Diseases, 2011Co-Authors: Juan M Gurevitz, Uriel Kitron, Leonardo A Ceballos, Maria Sol Gaspe, Julian A Alvaradootegui, Gustavo Fabian Enriquez, Ricardo E GurtlerAbstract:Background Transmission of Trypanosoma cruzi by Triatoma Infestans remains a major public health problem in the Gran Chaco ecoregion, where understanding of the determinants of house infestation is limited. We conducted a cross-sectional study to model factors affecting bug presence and abundance at sites within house compounds in a well-defined rural area in the humid Argentine Chaco. Methodology/Principal Findings Triatoma Infestans bugs were found in 45.9% of 327 inhabited house compounds but only in 7.4% of the 2,584 sites inspected systematically on these compounds, even though the last insecticide spraying campaign was conducted 12 years before. Infested sites were significantly aggregated at distances of 0.8–2.5 km. The most frequently infested ecotopes were domiciles, kitchens, storerooms, chicken coops and nests; corrals were rarely infested. Domiciles with mud walls and roofs of thatch or corrugated tarred cardboard were more often infested (32.2%) than domiciles with brick-and-cement walls and corrugated metal-sheet roofs (15.1%). A multi-model inference approach using Akaike's information criterion was applied to assess the relative importance of each variable by running all possible (17,406) models resulting from all combinations of variables. Availability of refuges for bugs, construction with tarred cardboard, and host abundance (humans, dogs, cats, and poultry) per site were positively associated with infestation and abundance, whereas reported insecticide use showed a negative association. Ethnic background (Creole or Toba) adjusted for other factors showed little or no association. Conclusions/Significance Promotion and effective implementation of housing improvement (including key peridomestic structures) combined with appropriate insecticide use and host management practices are needed to eliminate infestations. Fewer refuges are likely to result in fewer residual foci after insecticide spraying, and will facilitate community-based vector surveillance. A more integrated perspective that considers simultaneously social, economic and biological processes at local and regional scales is needed to attain effective, sustainable vector and disease control.
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genetic structure of Triatoma Infestans populations in rural communities of santiago del estero northern argentina
Infection Genetics and Evolution, 2008Co-Authors: Paula L Marcet, Ricardo E Gurtler, Uriel Kitron, Matias S Mora, Ana Paula Cutrera, L Jones, Ellen M DotsonAbstract:To gain an understanding of the genetic structure and dispersal dynamics of Triatoma Infestans populations, we analyzed the multilocus genotype of 10 microsatellite loci for 352 T. Infestans collected in 21 houses of 11 rural communities in October 2002. Genetic structure was analyzed at the community and house compound levels. Analysis revealed that vector control actions affected the genetic structure of T. Infestans populations. Bug populations from communities under sustained vector control (core area) were highly structured and genetic differentiation between neighboring house compounds was significant. In contrast, bug populations from communities with sporadic vector control actions were more homogeneous and lacked defined genetic clusters. Genetic differentiation between population pairs did not fit a model of isolation by distance at the microgeographical level. Evidence consistent with flight or walking bug dispersal was detected within and among communities, dispersal was more female-biased in the core area and results suggested that houses received immigrants from more than one source. Putative sources and mechanisms of re-infestation are described. These data may be use to design improved vector control strategies.
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comparative trial of effectiveness of pyrethroid insecticides against peridomestic populations of Triatoma Infestans in northwestern argentina
Journal of Medical Entomology, 2006Co-Authors: Maria C Cecere, Gonzalo M Vazquezprokopec, Uriel Kitron, Juan M Gurevitz, Leonardo A Ceballos, Joaquin E Zarate, Mario Zaidenberg, Ricardo E GurtlerAbstract:Abstract The effects of different pyrethroid insecticides, formulations, and doses on peridomestic populations of Triatoma Infestans (Klug) were evaluated in 128 houses with 148 identified infested peridomestic sites in northwestern Argentina between October 2003 and March 2005. Four treatments were randomly assigned within each community: two doses of 5% suspension concentrate β-cypermethrin in water applied with manual compression sprayers, the standard dose (S) at 50 mg and a double dose (2S) at 100 mg active ingredient (AI)/m2; and two emulsifiable concentrates diluted in diesel fuel and applied with power sprayers, 25% cypermethrin (100 mg [AI]/m2) (CF) and 10% permethrin (170 mg [AI]/m2) (DF). Infestation was assessed by timed manual collections with a dislodging agent at baseline, 5, 12, and 17 mo postspraying, and the sites found to be reinfested at 5 mo postspraying were selectively resprayed. Only 2S eliminated T. Infestans from all peridomestic sites up to 12 mo postspraying, and it was signifi...
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reinfestation sources for chagas disease vector Triatoma Infestans argentina
Emerging Infectious Diseases, 2006Co-Authors: Maria C Cecere, Gonzalo M Vazquezprokopec, Ricardo E Gurtler, Uriel KitronAbstract:Reinfestation by Triatoma Infestans after insecticide spraying has caused elimination efforts in the dry Chaco region to fail repeatedly. The sources and spatial extent that need to be considered to understand the reinfestation pattern and to plan a comprehensive control program were studied in 2 adjacent rural communities in northwestern Argentina from 1993 to 1997. The effects of external, residual, and primary sources on the reinfestation pattern were evaluated by using geographic information systems, satellite imagery, spatial statistics, and 5-year retrospective data for 1,881 sites. The reinfestation process depended on primary internal sources and on surrounding infested communities. In the dry Chaco, successfully reducing the risk for reinfestation in a community depends on treating all communities and isolated sites within 1,500 m of the target community. In addition, during the surveillance phase, spraying all sites within 500 m of new foci will delay reinfestation.
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flight initiation of Triatoma Infestans hemiptera reduviidae under natural climatic conditions
Journal of Medical Entomology, 2006Co-Authors: Juan M Gurevitz, Uriel Kitron, Leonardo A Ceballos, Ricardo E GurtlerAbstract:Flight dispersal of Triatoma Infestans Klug is probably the most important mechanism for house reinfestation at a village scale after residual spraying with insecticides. The aim of the current study was to estimate the flight initiation probability of field-collected T. Infestans and to assess how this probability was affected by sex, adult age, partial bloodmeal, and the presence of a host inaccessible for feeding. Four experimental series, each consisting of three to six consecutive nights and repeated measurements of flight initiation on each individually marked bug, were carried out in experimental huts inside closed cages under natural climatic conditions. We demonstrate that flight initiation probability of T. Infestans is much higher than previously reported, responds to temperature in a sigmoid manner, and is higher in females than males, and that the frequency distribution of the number of flights per individual is highly aggregated in female and male bugs. The age of adults had strong effects on flight initiation, whereas the presence of an inaccessible host and a partial bloodmeal exerted no significant effects in models controlling for the effects of bug weight-to-length ratio. The high flight potential found is consistent with the rapid changes in reinfestation patterns observed in the field. The present estimates of flight probabilities and the identification of factors modifying them provide essential knowledge for modeling reinfestation patterns and for improving control strategies of T. Infestans.
