Trypanosoma cruzi infection in Triatoma infestans and other triatomines: long-term effects of a control program in rural northwestern Argentina

The prevalence of Trypanosoma cruzi infection in Triatoma infestans, Triatoma guasayana, and Triatoma sordida was evaluated in Amamá and other neighboring rural villages in northwestern Argentina for five years after massive spraying with deltamethrin in 1992 and selective sprays thereafter. Local residents and expert staff collected triatomines in domiciliary and peridomestic sites. During 1993-1997, the prevalence of T. cruzi was 2.4% in 664 T. infestans, 0.7% in 268 T. guasayana, and 0.2% in 832 T. sordida. T. cruzi infection was more frequently detected in adult bugs and in triatomines collected at domiciliary sites. The infected T. guasayana and T. sordida were nymphs and adults, respectively, captured at peridomestic sites. The prevalence of T. cruzi infection in T. infestans decreased from 7.7% to 1.5% during the surveillance period, although that change was not statistically significant. Comparison of T. infestans infection rates before the control program and during surveillance showed a highly significant decrease from 49% to 4.6% in bedrooms, as well as a fall from 6% to 1.8% in peridomestic sites. Because of its infection with T. cruzi and frequent invasion of domiciliary areas and attacks on humans and dogs, T. guasayana appeared implicated as a putative secondary vector of T. cruzi in domestic and peridomestic sites during the surveillance period. T. sordida was the most abundant species, but it was strongly associated with chickens and showed little tendency to invade bedrooms

Effectiveness of residual spraying of peridomestic ecotopes with deltamethrin and permethrin on Triatoma infestans in rural western Argentina: a district-wide randomized trial.

OBJECTIVE: To compare the effectiveness of a single residual spraying of pyrethroids on the occurrence and abundance of Triatoma infestans in peridomestic ecotopes in rural La Rioja. METHODS: A total of 667 (32.8%) peridomestic sites positive for T. infestans in May 1999 were randomly assigned to treatment within each village, sprayed in December 1999, and reinspected in December 2000. Treatments included 2.5% suspension concentrate (SC) deltamethrin in water at 25 mg active ingredient (a.i.)/m(2) applied with: (a) manual compression sprayers (standard treatment) or (b) power sprayers; (c) 1.5% emulsifiable concentrate (EC) deltamethrin at 25 mg a.i./m(2); and (d) 10% EC cis-permethrin at 170 mg a.i./m(2). EC pyrethroids were diluted in soybean oil and applied with power sprayers. All habitations were sprayed with the standard treatment. FINDINGS: The prevalence of T. infestans 1-year post-spraying was significantly lower in sites treated with SC deltamethrin applied with manual (24%) or power sprayers (31%) than in sites treated with EC deltamethrin (40%) or EC permethrin (53%). The relative odds of infestation and catch of T. infestans 1-year post-spraying significantly increased with the use of EC pyrethroids, the abundance of bugs per site before spraying, total surface, and host numbers. All insecticides had poor residual effects on wooden posts. CONCLUSION: Most of the infestations probably originated from triatomines that survived exposure to insecticides at each site. Despite the standard treatment proving to be the most effective, the current tactics and procedures fail to eliminate peridomestic populations of T. infestans in semiarid rural areas and need to be revised

Effectiveness of residual spraying of peridomestic ecotopes with deltamethrin and permethrin on Triatoma infestans in rural western Argentina: a district-wide randomized trial

OBJECTIVE: To compare the effectiveness of a single residual spraying of pyrethroids on the occurrence and abundance of Triatoma infestans in peridomestic ecotopes in rural La Rioja. METHODS: A total of 667 (32.8%) peridomestic sites positive for T. infestans in May 1999 were randomly assigned to treatment within each village, sprayed in December 1999, and reinspected in December 2000. Treatments included 2.5% suspension concentrate (SC) deltamethrin in water at 25 mg active ingredient (a.i.)/m² applied with: (a) manual compression sprayers (standard treatment) or (b) power sprayers; (c) 1.5% emulsifiable concentrate (EC) deltamethrin at 25 mg a.i./m²; and (d) 10% EC cis-permethrin at 170 mg a.i./m². EC pyrethroids were diluted in soybean oil and applied with power sprayers. All habitations were sprayed with the standard treatment. FINDINGS: The prevalence of T. infestans 1-year post-spraying was significantly lower in sites treated with SC deltamethrin applied with manual (24%) or power sprayers (31%) than in sites treated with EC deltamethrin (40%) or EC permethrin (53%). The relative odds of infestation and catch of T. infestans 1-year post-spraying significantly increased with the use of EC pyrethroids, the abundance of bugs per site before spraying, total surface, and host numbers. All insecticides had poor residual effects on wooden posts. CONCLUSION: Most of the infestations probably originated from triatomines that survived exposure to insecticides at each site. Despite the standard treatment proving to be the most effective, the current tactics and procedures fail to eliminate peridomestic populations of T. infestans in semiarid rural areas and need to be revised

Effectiveness of residual spraying of peridomestic ecotopes with deltamethrin and permethrin on Triatoma infestans in rural western Argentina: a district-wide randomized trial

Fil: Gürtler, Ricardo E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Laboratorio de Ecología General; Argentina.Fil: Canale, Delmi M. Coordinación Nacional de Control de Vectores; Argentina.Fil: Spillmann, Cynthia. Coordinación Nacional de Control de Vectores; Argentina.Fil: Stariolo, Raúl. Coordinación Nacional de Control de Vectores; Argentina.Fil: Salomón, Oscar D. ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación de Endemo-Epidemias; Argentina.Fil: Blanco, Sonia. Coordinación Nacional de Control de Vectores; Argentina.Fil: Segura, Elsa L. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología; Argentina.Objective: To compare the effectiveness of a single residual spraying of pyrethroids on the occurrence and abundance of Triatoma infestans in peridomestic ecotopes in rural La Rioja. Methods: A total of 667 (32.8%) peridomestic sites positive for T. infestans in May 1999 were randomly assigned to treatment within each village, sprayed in December 1999, and reinspected in December 2000. Treatments included 2.5% suspension concentrate (SC) deltamethrin in water at 25 mg active ingredient (a.i.)/m(2) applied with: (a) manual compression sprayers (standard treatment) or (b) power sprayers; (c) 1.5% emulsifiable concentrate (EC) deltamethrin at 25 mg a.i./m(2); and (d) 10% EC cis-permethrin at 170 mg a.i./m(2). EC pyrethroids were diluted in soybean oil and applied with power sprayers. All habitations were sprayed with the standard treatment. Findings: The prevalence of T. infestans 1-year post-spraying was significantly lower in sites treated with SC deltamethrin applied with manual (24%) or power sprayers (31%) than in sites treated with EC deltamethrin (40%) or EC permethrin (53%). The relative odds of infestation and catch of T. infestans 1-year post-spraying significantly increased with the use of EC pyrethroids, the abundance of bugs per site before spraying, total surface, and host numbers. All insecticides had poor residual effects on wooden posts. Conclusion: Most of the infestations probably originated from triatomines that survived exposure to insecticides at each site. Despite the standard treatment proving to be the most effective, the current tactics and procedures fail to eliminate peridomestic populations of T. infestans in semiarid rural areas and need to be revised

Exploration for Triatoma virus (TrV) infection in laboratory-reared triatomines of Latin America: a collaborative study

Triatoma virus (TrV) is a small, non-enveloped virus that has a +ssRNA genome and is currently classified under the Cripavirus genus of the Dicistroviridae family. TrV infects haematophagous triatomine insects (Hemiptera: Reduviidae), which are vectors of American Trypanosomiasis (Chagas disease). TrV can be transmitted through the horizontal fecal-oral route, and its infection causes either deleterious sublethal effects or even death of laboratory insect colonies. Various species of triatomines from different regions of Latin America are currently being reared in research laboratories, with little or no awareness of the presence of TrV; therefore, any biological conclusion drawn from experiments on insects infected with this virus is inherently affected by the side effects of its infection. In this study, we developed a mathematical model to estimate the sample size required for detecting a TrV infection. We applied this model to screen the infection in feces of triatomines belonging to insectaries from 13 Latin American countries, carrying out the identification of TrV by using reverse transcriptase PCR. TrV was detected in samples coming from Argentina, which is the country where several years ago the virus was first isolated from Triatoma infestans (Hemiptera: Reduviidae). Interestingly, several colonies from Brazil were also found infected with the virus. This positive result widens the TrV?s host range to a total of 14 triatomine species. Our findings suggest that many triatomine species distributed over a large region of South America may be naturally infected with TrV.Fil: Marti, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Echeverria, Maria Gabriela. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Microbiología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Susevich, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Ceccarelli, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Balsalobre, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Canale, Delmi Margarita. Centro de Referencia de Vectores, Coordinación Nacional de Control de Vectores, Pabellón Rawson-Hospital Colonia; ArgentinaFil: Stariolo, Raúl Luis. Centro de Referencia de Vectores, Coordinación Nacional de Control de Vectores, Pabellón Rawson-Hospital Colonia; ArgentinaFil: Guérin, Diego M. A.. Universidad del País Vasco; España. Consejo Superior de Investigaciones Cientificas; España. Universidad Politécnica de Valencia; EspañaFil: González Cifuentes, Nadia L.. Universidad de Los Andes; ColombiaFil: Guhl, Felipe. Universidad de Los Andes; ColombiaFil: Bacigalupo, Antonella. Universidad de Chile; ChileFil: Cattan, Pedro E.. Universidad de Chile; ChileFil: Garcıa, Alejandro. Secretaria Regional Ministerial de Salud de Coquimbo; ChileFil: Villacis, Anita G.. Pontificia Universidad Catolica del Ecuador; EcuadorFil: Grijalva, Mario J.. Pontificia Universidad Catolica del Ecuador; Ecuador. Ohio University; Estados UnidosFil: Solorzano, Elizabeth. Universidad de San Carlos; GuatemalaFil: Monroy, Carlota. Universidad de San Carlos; GuatemalaFil: Espinoza Blanco, Yrma. Universidad Nacional Mayor de San Marcos; PerúFil: Cordova Benzaquen, Eleazar. Universidad Nacional San Agustín de Arequipa; PerúFil: Ruelas llerena, Nancy. Universidad Nacional San Agustín de Arequipa; PerúFil: Guzmán loayza, Miriam. Dirección Regional de Salud Moquegua; PerúFil: Caceres, Abraham G.. Universidad Nacional Mayor de San Marcos; PerúFil: Vences Blanco, Mauro O.. Universidad Nacional Autónoma de México; MéxicoFil: Salazar Schettino, Paz María. Universidad Nacional Autónoma de México; MéxicoFil: Martínez Martínez, Ignacio. Universidad Nacional Autónoma de México; MéxicoFil: Espinoza Gutiérrez, Bertha. Universidad Nacional Autónoma de México; MéxicoFil: Mojoli, Andrés. Centro para el Desarrollo de la Investigación Científica. Asunción; ParaguayFil: Rojas de Arias, Antonieta. Centro para el Desarrollo de la Investigación Científica. Asunción; ParaguayFil: Feliciangeli, M. Dora. Universidad de Carabobo Maracay; VenezuelaFil: Rivera Mendoza, Pedro. Fundación para el Desarrollo; NicaraguaFil: Rozas Dennis, Gabriela Susana. Universidad Nacional del Sur; ArgentinaFil: Sánchez Eugenia, Rubén. Unidad de Biofísica; EspañaFil: Aguirre, Jon. Unidad de Biofísica; España. Fundación Biofísica Bizkaia; EspañaFil: Viguera, Ana R.. Unidad de Biofísica; EspañaFil: Hernádez Suárez, Carlos M.. Universidad de Colima; México. Unidad Monterrey; MéxicoFil: Vilchez, Susana. Universidad de Granada; EspañaFil: Osuna, Antonio. Universidad de Granada; EspañaFil: Gorla, David Eladio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de la Rioja. - Secretaria de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Esteban, Lidia. Universidad Industrial Santander; ColombiaFil: Angulo, Vıctor M.. Universidad Industrial Santander; ColombiaFil: Querido, Jailson F. B. Unidad de Biofísica; España. Fundación Biofísica Bizkaia; España. Universidad Nova de Lisboa; PortugalFil: Silva, Marcelo S.. Universidad Nova de Lisboa; PortugalFil: Marques, Tatiane. Universidade Federal do Triangulo Mineiro; BrasilFil: Anhe, Ana Carolina B. M.. Universidade Federal do Triangulo Mineiro; BrasilFil: Gomez Hernandez, Cesar. Universidade Federal do Triangulo Mineiro; BrasilFil: Ramirez, Luis E.. Universidade Federal do Triangulo Mineiro; BrasilFil: Rabinovich, Jorge Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Diotaiuti, Liléia. Centro de Pesquisas Rene Rachou-FIOCRUZ; BrasilFil: Guerin Aguilar , Diego Marcelo. Universidad del País Vasco; España. Unidad de Biofísica; España. Fundación Biofísica Bizkaia; Españ