[Operational aspects of Triatoma brasiliensis control]. / Aspectos operacionais do controle do Triatoma brasiliensis.

Vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. Between August 1996 and December 1997 we conducted a study on reinfestation of houses after spraying in a county in the State of Ceará. Of 277 houses examined, 113 (40.8%) were infested (21.7% intradomiciliary and 35.4% peridomiciliary). Of the 433 Triatominae collected, 207 were Triatoma brasiliensis (49% of which intradomiciliary, with a mean of 1.8 insects/house) and 226 were Triatoma pseudomaculata (97% peridomiciliary). The age structure of the two indicated a univoltine development cycle for T. brasiliensis and two cycles per year for T. pseudomaculata. Four months after spraying with deltamethrin SC 25mg ia/m2, 9.7% of the houses were still positive, mainly with peridomestic infestations. Intradomiciliary wall bioassays showed persistence of the insecticide up to 9 months after spraying. Considering the high potential for recolonization of treated premises from sylvatic foci, we propose an operational strategy combining traditional evaluations and community-based surveillance with increased selective interventions and community education.

[Peridomiciliary changes and implications for Triatoma brasiliensis control]. / Alterações do peridomicílio e suas implicações para o controle do Triatoma brasiliensis.

A total of 9,906 annexes from 1,541 rural dwellings of Boa Viagem County, Ceará, Brazil, infested by Triatoma brasiliensis and Triatoma pseudomaculata were investigated and immediately sprayed with pyrethroid insecticide, followed by revisions at 6, 12, and 18 months. The initial infestation rate of annexes was 4.0%, with predominant infestation in animal shelters (7.0%). Mean insect density was low, regardless of triatomine species or type of annex. A progressive decrease in the number of initial annexes was observed (66% of remaining annexes), mainly those classified as "piles of materials". Only 3% of the annexes were modified by the population. New constructed annexes were important as new foci of infestation. Some 25% were infested at the end of observation period, significantly more than the "old" annexes (4.0%), a difference attributed to insecticide spraying at the beginning of the intervention. Reinfestation occurred slowly and was more frequent in animal shelters No differences were observed between traditional pyrethroid and slow-release organophosphate formulations. Selective spraying of "new" annexes is recommended.

[Focal and total residual insecticide spraying to control Triatoma brasiliensis and Triatoma pseudomaculata in Northeast Brazil]. / Tratamentos focais e totais com inseticidas de ação residual para o controle de Triatoma brasiliensis e Triatoma pseudomaculata no Nordeste brasileiro.

To efficiently control the triatomines Triatoma brasiliensis and Triatoma pseudomaculata, a field trial was performed to compare conventional versus focal spraying of deltamethrin 5% SC at 25 mg a. i./m2 and the slow-release organophosphate malathion 8.3% SR at 2g a. i./m2. The assay took place in the county of Boa Viagem, Ceará State, with 1541 households, randomly separated into 4 groups. Two of them received focal spraying: PT, treated with deltamethrin indoors and in the peridomicile, and PL, which received slow-release malathion in the same circumstances. The other groups received conventional, i.e., total application: PT with deltamethrin in the intra- and peridomicile, and PL, which was treated with deltamethrin indoors and slow-release malathion in the peridomicile. Entomological surveys at 6 and 12 months post-treatment showed better results for mixed treatment, the PL group, probably due to good indoor performance for the pyrethroid and better performance of the slow-release formulation under the hostile peridomiciliary conditions. Domestic animal shelters underwent numerous modifications over the course of the year, fostering reduced insecticide performance in the peridomicile.

Sobre o foco de Triatomineos domiciliados na baixada fluminense. / Focus Triatoma infestans focus domiciled in Baixada Fluminense

Os autores relatam os resultados de inquerito entomologico realizado nos municipios de Duque de Caxias e Nova Iguacu (RJ), confrontando-os com dados ate entao disponiveis. Foi comprovada a infestacao intradomiciliar por T. infestans em uma area correspondente a dezenove, de um total de oitenta e sete localidades, pesquisadas, significando que houve uma consideravel expansao do foco inicial. Ao contrario, a infestacao e densidade, ou a relacao triatomineos/casa, foi reduzida. Com base nos dados apresentados e em outras informacoes, os autores consideram que a area nao apresentaria condicoes muito favoraveis a colonizacao por triatomineos, e admitem que o foco possa ser rapidamente eliminado pelo uso de inseticidas de acao residual