Background: Triatoma spinolai is the only wild vector for Chagas disease in Chile and its epidemiological importance is being studied.
Aim: 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.
Methods: Four hundred ninety two specimens of Triatoma spinolai were collected in four sites of a quarry zone, 14 kilometers north of Santiago. Their maturity and the presence of Trypanosoma cruzi in their intestinal contents were determined.
Results: Mean tripano-triatomine index was 26.02 +/- 2% (range 0 to 34% in different sites). The proportion of infected insects increased along with their maturity and 58% 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.
Conclusions: The studied zone has a potential epidemiological risk for the transmission of Chagas disease by Triatoma spinolai.