Photoinactivation of Trypanosoma cruzi in red cell suspensions with thiopyrylium

Chagas disease, endemic in rural areas of Mexico, Central and South America, is caused by the protozoan parasite, Trypanosma cruzi, which is spread by the Reduviid bug and also by transfusion or organ transplant. Transmission of the organism from asymptomatic donors to immunocompromised recipients, leads to clinically apparent disease. With recent immigration patterns, T. cruzi is now becoming an increasing problem in non-endemic areas of North America and Europe. Blood screening tests for T. cruzi are being developed, and one test is currently licensed by the United States Food and Drug Administration and has been implemented in some US blood centers. This study alternatively investigates the potential for a novel DNA-intercalating photosensitizer, thiopyrylium (TP), to inactivate T. cruzi in red cell suspensions. With complete inactivation using 6.3 microM of TP and 1.1J/cm(2) red light treatment, results suggest that the organism is highly sensitive to photoinactivation under conditions much less stringent than those that have been previously demonstrated to maintain red cell (RBC) properties during 42 day storage.