Parasitological and epidemiological aspects of Trypanosoma cruzi seropositive blood donors

Background: After the interruption of the transmission of Chagas disease via vector insects in Chile, there is little available epidemiological information about this parasitosis in blood banks. Aim: To update the rates of T cruzi positive blood donors. To measure parasitological and epidemiological parameters in blood donors with anti T cruzi antibodies. Material and Methods: An ELISA-T cruzi test was carried out in 30,309 blood donors between 2000 and 2004. In 75 blood donors with an ELISA-T cruzi positive test and 79 donors with negative ELISA (controls), a survey about personal or parental history of biting by a kissing bug (Triatomine), was performed. A blood sample was also obtained to perform Polymerase Chain Reaction (PCR) for T cruzi and a xenodiagnostic test. Results: Annual frequency of positive ELISA for T cruzi serum antibodies in blood donors varied from 0.31% to 0.45%. Twenty eight percent of subjects with positive and 6% of subjects with negative specific antibodies answered the survey about biting. PCR and xenodiagnostic test were positive in 52 (69%) and 16 (21%) of positive ELISA-T cruzi test blood donors, respectively. Xenodiagnostic was also positive in 5 individuals who had a negative PCR. Conclusions: Seroprevalence of T cruzi antibodies decreased from 3% in 1968 to 0.3% in 2004