Detection of Trypanosoma cruzi in untreated chronic chagasic patients is improved by using three parasitological methods simultaneously

Objectives: This study compared three parasitological methods applied simultaneously in individuals with untreated chronic Chagas' disease in order to determine their individual and combined performances. Methods: From a total of 100 chronic chagasic patients from endemic areas of Chile, with informed consent, we extracted 2 mL of peripheral venous blood for PCR (PCR-B) and applied two xenodiagnosis (XD) boxes with seven uninfected Triatoma infestans nymphs each for microscopic examination and PCR of faecal samples of the triatomines fed on each patient (PCR-XD). The PCR-B and PCR-XD reactions were performed with oligonucleotides 121 and 122, which anneal to the four constant regions of the minicircles of Trypanosoma cruzi kinetoplasts. The 330 bp PCR product was analysed by electrophoresis in a 2% agarose gel and visualized by staining with ethidium bromide. Results: PCR-B detected T. cruzi in 58% of the cases, while PCR-XD proved to be more sensitive than XD (67% versus 14%, respect