RESUMO
BACKGROUND: Allogeneic blood transfusions are the second most frequent route of Chagas' disease transmission in countries where the disease is endemic. The prevention of transfusion-associated Chagas' disease has been attempted through clinical and serologic screening of blood donors and/or by the addition of trypanomicidal substances such as gentian violet (GV) to stored blood for 24 hours. The present study describes an alternative method of chemoprophylaxis of transfusion-associated Chagas' disease that reduces the sterilization time by using a combination of low-concentration GV, ascorbic acid (AA), and photoradiation with visible light. STUDY DESIGN AND METHODS: To better reproduce the conditions of blood transfusion in developing areas, normal human blood was collected in blood collection bags, infected with different concentrations of Trypanosoma cruzi, and treated with GV, AA, and photoradiation. Mice were then inoculated with the T. cruzi-infected human blood that had been stored at different incubation intervals. Active parasites were sought in mouse blood for parasitologic diagnosis and serologic evaluation (mice inoculation, blood culture, and indirect immunofluorescence). RESULTS: The association of GV (250 micrograms/mL), and photoradiation with visible light (75W) sterilized T. cruzi-infected blood even after treatment for less than 30 minutes and even when chagasic blood was treated with low-concentration GV (62.5 micrograms/mL for 30 min). Moreover, the trypanomicidal activity of GV associated with AA and photoradiation with visible light was found even when blood was infected with a 10-fold parasite concentration. CONCLUSIONS: The proposed alternative prophylactic method is reproducible, easy to perform, and inexpensive, and it may have practical importance in endemic areas where serologic screening of donor blood is not always available. In addition, the reduction of the GV trypanomicidal concentration might further minimize the potential for GV-related side effects.