title: Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid.
abstract: BACKGROUND
  Despite years of efforts towards the elimination of Triatoma infestans in Brazil, residual foci still persist in some areas of the States of Bahia and Rio Grande do Sul. The persistence of these T. infestans populations in the country has two different origins of equal concern: operational failures or insecticide resistance. Thus, the objective of this study was to characterize the susceptibility profile of the residual Brazilian populations of T. infestans to deltamethrin.
  
  
  METHODS
  The susceptibility reference lineage was derived from Cipein/Argentina. The populations studied were manually collected using a dislodging agent in peridomiciles in the States of Bahia (Novo Horizonte) and of Rio Grande do Sul (Santa Rosa and Doutor Maurício Cardoso). Serial dilutions of deltamethrin were prepared and applied at the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed the mortality of a diagnostic dose of 1xLD99 (2.76ng a.i./nymph) determined for the susceptibility reference lineage.
  
  
  RESULTS
  The susceptibility profile characterization of the T. infestans populations revealed an RR50 ranging from 1.73 to 3.26. The mortality percentage in response to a diagnostic dose was 100%. The results obtained in the quantitative and qualitative assays corresponded for all populations.
  
  
  CONCLUSIONS
  The results of this study indicate that the persistence of residual foci of T. infestans in Bahia and Rio Grande do Sul is not related to insecticide resistance but may be associated with operational failures. In Rio Grande do Sul, we must consider the possibility of continuous reinfestation by Argentinian individuals, which justifies active and efficient epidemiological surveillance.
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Grasielle Caldas D'avila
authors.initials: GC
authors.lastname: Pessoa
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Aline Cristine Luiz
authors.initials: AC
authors.lastname: Rosa
authors.affiliation: Laboratório Central de Saúde Pública do Rio Grande do Sul, Instituto de Pesquisas Biológicas, Secretaria de Saúde do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Cleonara
authors.initials: C
authors.lastname: Bedin
authors.affiliation: Laboratório Central de Saúde Pública do Rio Grande do Sul, Instituto de Pesquisas Biológicas, Secretaria de Saúde do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Tânia
authors.initials: T
authors.lastname: Wilhelms
authors.affiliation: Laboratório Central de Saúde Pública do Rio Grande do Sul, Instituto de Pesquisas Biológicas, Secretaria de Saúde do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Fernanda de
authors.initials: Fd
authors.lastname: Mello
authors.affiliation: Laboratório Central de Saúde Pública da Bahia, Diretoria de Vigilância Epidemiológica, Secretaria de Saúde da Bahia, Salvador, Bahia, Brazil.
authors.forename: Helder Silveira
authors.initials: HS
authors.lastname: Coutinho
authors.affiliation: Laboratório Central de Saúde Pública da Bahia, Diretoria de Vigilância Epidemiológica, Secretaria de Saúde da Bahia, Salvador, Bahia, Brazil.
authors.forename: Eduardo Oyama Lins
authors.initials: EO
authors.lastname: Fonseca
authors.affiliation: Laboratório Central de Saúde Pública da Bahia, Diretoria de Vigilância Epidemiológica, Secretaria de Saúde da Bahia, Salvador, Bahia, Brazil.
authors.forename: Roberto Fonseca
authors.initials: RF
authors.lastname: dos Santos
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Liléia
authors.initials: L
authors.lastname: Diotaiuti
mesh_terms: D000818:Animals; D001681:Biological Assay; D001938:Brazil; D014355:Chagas Disease / Q000635:transmission; D007303:Insect Vectors; D007305:Insecticide Resistance; D007928:Lethal Dose 50; D009570:Nitriles; D011722:Pyrethrins; D014224:Triatoma
chemical_list: D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin