Trypanosoma cruzi: polymerase chain reaction-based detection in dried feces of Triatoma infestans.

PCR was employed to detect Trypanosoma cruzi DNA in Triatoma infestans dry fecal spots collected on filter papers. Both insects fed on experimentally infected monkeys and insects collected in a Paraguayan endemic area for Chagas' disease were examined. When the insects fed on a chronically infected monkey with low parasitemia as revealed by direct microscopic observation (DMO), T. cruzi was detected in the insect feces by PCR as soon as 2 days postfeeding. When the same experiment was performed on monkeys with parasitemia levels below the limit of detection by DMO, the degree of positivity found through PCR-Southern hybridization, applied on Day 8 postfeeding, was superior to that obtained through xenoculture. These results suggest that PCR can be used to speed the xenodiagnosis results with great sensitivity. On the other hand, when applied to the feces of triatomines collected in the field, 84% were positive by PCR-Southern hybridization, whereas only 26% were positive by DMO. Therefore, PCR could also be applied to the monitoring of the infection status of triatomines which infest rural dwellings by examining only the feces left on paper sensors hung on the walls of the houses.