Comparative xenodiagnosis with three triatomine species of different hosts with natural and experimental chronic infections with Trypanosoma (Schizotrypanum) cruzi.

Simultaneous xenodiagnosis was made of 29 patients with chronic Chagas's disease, six naturally infected opossums (Didelphis azarae) and of a Rhesus monkey with an experimental chronic infection with Trypanosoma (Schizotrypanum) cruzi (Peru strain). Patients and opossums were from an endemic area in the state of Bahia, Brazil, where Panstrongylus megistus is the sole domiciliary vector of the disease to man. Various instars of P. megistus Triatoma infestans and Rhodnius prolixus were used. The proportion of bugs infected with compared with bloodmeal intake by a computer programme using linear logistic analysis. The analysis showed that there are intrinsic interspecific differences in susceptibility to infection with Trypanosoma cruzi between the three triatomine species used and that subsequent infection of bugs with T. cruzi is correlated with the quantity of blood ingested. The results show that interspecific differences of bloodmeal size and intrinsic differences in susceptibility to T. cruzi between triatomine species are limiting factors for the standardization and interpretation of the results of xenodiagnosis.