RESUMEN
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 percent to 0.45 percent. Twenty eight percent of subjects with positive and 6 percent of subjects with negative specific antibodies answered the survey about biting. PCR and xenodiagnostic test were positive in 52 (69 percent) and 16 (21 percent) 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 percent in 1968 to 0.3 percent in 2004.