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 Sout h and Central America. Blood transfusion is the second most common way in which this disease is transmitted. Several studies have reported f inding Trypanosoma cruzi-infected blood in blood banks in endemic area s. 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 1 993 and analyzed by enzyme-linked immunosorbent assay using crude epim astigote extract from the Brazil strain of T. cruzi. Of 162 samples ex amined in December 1992, 12.1%, 13.9%, and 74% were seropositive, inde terminate, and seronegative, respectively. Of 173 samples taken in May 1993, 6.2%, 17.9%, 75.9% were seropositive, indeterminate, and serone gative, respectively. Western blot analysis of these sera using sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 7.5% gels sep arated 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 dise ase even in areas of endemic countries where the vector is not present .