Blood donors in a vector-free zone of Ecuador potentially infected with Trypanosoma cruzi

Chagas' disease is a serious health problem for the population of South and Central America. Blood transfusion is the second most common way in which this disease is transmitted. Several studies have reported finding Trypanosoma cruzi-infected blood in blood banks in endemic areas. Serum samples were taken from the Red Cross blood bank in Quito, a nonendemic and vector free zone of Ecuador, in December 1992 and May 1993 and analyzed by enzyme-linked immunosorbent assay using crude epimastigote extract from the Brazil strain of T. cruzi. Of 162 samples examined in December 1992, 12.1%, 13.9%. and 74% were seropositive, indeterminate, and seronegative, respectively. Of 173 samples taken in May 1993, 6.2%. 17.9%, 75.9% were seropositive, indeterminate, and seronegative, respectively. Western blot analysis of these sera using sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 7.5% gels separated T. cruzi epimastigote antigen proteins, and revealed a reaction with a 205-kD doublet antigen with most of the seropositive samples. These results indicate the necessity for long-term screening of blood bank donors to reduce the risk of transfusion transmission of the disease even in areas of endemic countries where the vector is not present.