[Risk of Chagas disease through transfusions in the Americans].

The safety of blood transfusion depends on a country's laws, decrees and/or regulations concerning the collection, production and use of blood and blood derivatives. It also needs governmental enforcement of those instruments, as well as trained health professionals to obtain blood and produce blood derivatives, following total quality control procedures both at collection and production, and use. By 1998, all Latin American countries had laws, decrees and/or regulations that governed the production and use of blood, with the exception of El Salvador and Nicaragua. During the past six decades, economic need in Latin America has promoted migration to urban areas. Consequently, at present time, more than 60% of the population live in cities, which increases the probability of finding blood infected by Trypanosoma cruzi among donors. Unless all the blood from infected donors is discarded, the possibility of transmitting infection by transfusion remains. Moreover, infection by T. cruzi through transfusion is a potential problem in developed countries, now that tens of thousands of individuals from Latin America have migrated to the United States, Canada, western Europe, Australia and Japan. When donors are not screened for T. cruzi, the risk of transfusing infected blood is greater at higher prevalence rates of infection in the donor population; it also increases with the number of transfusions received by the recipient. In 1993, Bolivia presented the highest risk of receiving infected blood and becoming infected with T. cruzi; this country was followed by Colombia, El Salvador and Paraguay. As the coverage of HIV screening became almost universal, the probability of receiving blood infected by HIV and becoming infected was low in all countries. In the case of hepatitis B (HVB), the highest probability of infection was in Bolivia, Nicaragua and Guatemala. This probability was even greater for Hepatitis C (HVC), given the low coverage of donor screening in all countries. In absolute numbers, the highest potential for occurrence of cases of T. cruzi infection were present in Bolivia, the greatest number of HVC cases in Colombia, and the most cases of HVB in Nicaragua. Only in two countries, Bolivia and Colombia, HIV could be potentially transmitted by blood transfusion. Although the situation has improved since 1993, and 100% of donors are being screened for T. cruzi in Argentina, Colombia, Ecuador, El Salvador, Honduras, Paraguay, Uruguay and Venezuela, success will only be assured by: total enforcement of the law by governments; implementation of altruistic and volunteer blood donations, exclusively; 100% of donors are screened for communicable diseases; the collection, processing and use of blood strictly follow quality control norms; reagents used in diagnosis are adequate, and the use of blood and blood derivatives is limited to cases where it is only absolutely necessary.