Certifying the interruption of Chagas disease transmission by native vectors : cui bono?

Certifying the absence of Chagas disease transmission by native vectors lacks scientific grounds and weakens long-term control-surveillance systems to the detriment of people living under risk conditions. Instead, a regular "certification of good practice" (including vector control-surveillance, case detection/patient care and blood safety) could help achieve sustained disease control

Distribution of Pyrethroid Resistant Populations of Triatoma infestans in the Southern Cone of South America

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. 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 (RR 50 ). The statistical descriptive analysis of showed that the frequency distribution of the Log(LD 50 ) is bimodal, suggesting the existence of two statistical groups. A significant model including 5 environmental variables shows the geographic distribution of high and low LD 50 groups with a particular concentration of the highest LD 50 populations over the region identified as the putative center of dispersion of T. infestans.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 LD 50 and RR 50 suggest RR 50 might not be the best indicator of insecticide resistance in triatomines.Fil: Bustamante Gomez, Marinely. Centro de Pesquisas René Rachou. Laboratório de Referência em Triatomínueos e Epidemiologia da Doença de Chagas; BrasilFil: Gonçalves Diotaiuti, Liléia. Centro de Pesquisas René Rachou. Laboratório de Referência em Triatomínueos e Epidemiologia da Doença de Chagas; BrasilFil: Gorla, David Eladio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

Biological aspects of crosses between Triatoma maculata (Erichson,1848) andTriatoma pseudomaculataCorrêa & Espínola, 1964(Hemiptera: Reduviidae).

Submitted by Nuzia Santos ([email protected]) on 2013-06-19T12:56:04Z No. of bitstreams: 1 18.BELISÁRIO CJ.pdf: 152863 bytes, checksum: 67f8ec379a376c3ac99aa722d09aa631 (MD5)Made available in DSpace on 2013-06-19T12:56:04Z (GMT). No. of bitstreams: 1 18.BELISÁRIO CJ.pdf: 152863 bytes, checksum: 67f8ec379a376c3ac99aa722d09aa631 (MD5) Previous issue date: 2007Fundação Oswaldo Cruz. Centro de Pesquisa René Rachou. Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisa René Rachou. Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas. Belo Horizonte, MG, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisa René Rachou. Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas. Belo Horizonte, MG, Brasil.Due to morphological similarities between Triatoma maculataand T. pseudomaculata, which comprise the “maculate complex”, both had been regarded as the same species until 1964. Considering that the studies on triatomine hybridization permit hypotheses formulation concerning origin and divergence of species, enabling a quantitative analysis of taxonomic relationships between species, the present investigation was aimed at broadening further understanding related to the capacity of hybrid production by determining the degree ofreproductive isolation between T. maculataand T. pseudomaculata. Our results have demonstrated that T. maculata and T. pseudomaculatashowed no differences regarding reproduction patterns and they are able to cross, gen-erating infertile hybrid