info:eu-repo/semantics/article
Unexpected failures to control chagas disease vectors with pyrethroid spraying in Northern Argentina
Fecha
2012-11Registro en:
Gurevitz, Juan Manuel; Gaspe, Maria Sol; Enriquez, Gustavo Fabián; Vassena, Claudia Viviana; Alvarado Otegui, Julián Antonio; et al.; Unexpected failures to control chagas disease vectors with pyrethroid spraying in Northern Argentina; Entomological Society of America; Journal of Medical Entomology; 49; 6; 11-2012; 1379-1386
0022-2585
1938-2928
CONICET Digital
CONICET
Autor
Gurevitz, Juan Manuel
Gaspe, Maria Sol
Enriquez, Gustavo Fabián
Vassena, Claudia Viviana
Alvarado Otegui, Julián Antonio
Provecho, Yael Mariana
Mougabure Cueto, Gastón Adolfo
Picollo, Maria Ines
Kitron, Uriel
Gurtler, Ricardo Esteban
Resumen
Effectiveness of the elimination efforts against Triatoma infestans (Klug) in South America through residual application of pyrethroid insecticides has been highly variable in the Gran Chaco region. We investigated apparent vector control failures after a standard community-wide spraying with deltamethrin SC in a rural area of northeastern Argentina encompassing 353 houses. Insecticide spraying reduced house infestation less than expected: from 49.5% at baseline to 12.3 and 6.7% at 4 and 8 mo postspraying, respectively. Persistent infestations were detected in 28.4% of houses, and numerous colonies with late-stage bugs were recorded after the interventions. Laboratory bioassays showed reduced susceptibility to pyrethroids in the local bug populations. Eleven of 14 bug populations showed reduced mortality in diagnostic dose assays (range, 35 ± 5% to 97 ± 8%) whereas the remainder had 100% mortality. A fully enclosed residual bug population in a large chicken coop survived four pyrethroid sprays, including two double-dose applications, and was finally suppressed with malathion. The estimated resistance ratio of this bug population was 7.17 (range, 4.47-11.50). Our field data combined with laboratory bioassays and a residual foci experiment demonstrate that the initial failure to suppress T. infestans was mainly because of the unexpected occurrence of reduced susceptibility to deltamethrin in an area last treated with pyrethroid insecticides 12 yr earlier. Our results underline the need for close monitoring of the impact of insecticide spraying to provide early warning of possible problems because of enhanced resistance or tolerance and determine appropriate responses.