ABSTRACT
Triatoma spinolai is the only wild vector for Chagas disease in Chile and its epidemiological importance is being studied. To study the proportion of insects infected with Trypanosoma cruzi (tripano-triatomine index) in a zone with epidemiological risk in the Metropolitan Region of Chile, 492 specimens of triatoma spinolai were collected in 4 sites of a quarry zone, 14 kilometers north of Santiago. Their maturity and the presence of Trypanosoma cruzi in their intestinal contents were determined. Mean Tripano-triatomine index was 26.02ñ2 percent (range 0 to 34 percent in different sites). The proportion of infected insects increased along with the maturity and 58 percent of adult specimens were infected. There was a seasonal variation of the proportion of infected specimens being lower in march and June and higher in July and February. The studied zone has a potential epidemiological risk for the transmission of Chagas disease by Triatoma spinolai