Trypanosoma cruzi parasitemia in US blood donors with serologic evidence of infection.

Trypanosoma cruzi infection (which causes Chagas disease) is typically undiagnosed and persists if untreated. We sought to affirm that T. cruzi-seropositive US blood donors have persistent infection with demonstrable parasitemia long after acquisition of infection. Fifty-two previously identified seropositive donors (positive by 2 methods) provided up to 3 blood specimens for testing by polymerase chain reaction (PCR) and hemoculture; most participants (67%) provided only 1 specimen. When evaluated 2 decades after immigration, 33 donors (63%) had PCR evidence of parasitemia; 3 also had culture-confirmed infection. This affirmation that bloodstream parasites are detectable--and potentially transmissible--decades after immigration strengthens the rationale for donor screening.