We assessed the distribution of Trypanosoma cruzi infection in peridomestic triatomines collected manually at a district-wide scale in rural villages around Olta, Western Argentina, and typed the isolated strains according to their pathogenicity to laboratory mice. Of 1623 triatomines examined, only 14 (0.9%) were infected with T. cruzi based on microscopical examination of feces. The prevalence of T. cruziinfection was 0.8% in Triatoma infestans, 2.3% in T. guasayana, and nil in T. garciabesi, T. platensis, and T. eratyrusiformis. Local transmission occurred in kitchens, store-rooms and goat corrals or nearby, though at very low levels. T. cruzi was detected by at least one parasitological method in 11 (79%) of 14 microscope-positive bugs. Hemoculture was the most sensitive method (67%) followed by culture of organ homogenates, histopathology or xenodiagnosis of inoculated suckling mice (55-58%), and culture of microscope-positive bug feces (46%). The evidence suggests that most of the isolated T. cruzistrains would be myotropic type III. Our study establishes for the first time that peridomestic, microscope-positive T. guasayananymphs were actually infected with T. cruzi, and may be implicated as a putative secondary vector of T. cruziin domestic or peridomestic sites.

Fil: Lauricella, Marta A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología Dr. Mario Fatala Chaben; Argentina.

Fil: Stariolo, Raúl L. Coordinación Nacional de Control de Vectores; Argentina.

Fil: Segura, Elsa Leonor. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología Dr. Mario Fatala Chaben; Argentina.

Fil: Riarte, Adelina Rosa. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología Dr. Mario Fatala Chaben; Argentina.

Fil: Gürtler, Ricardo E. Universidad de Buenos Aires. Laboratorio de Eco-Epidemiología; Argentina.