Photoinactivation of Leishmania donovani infantum in red cell suspensions by a flexible thiopyrylium sensitizer

Background and Objectives  Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania, which are intracellular parasites of monocytes and macrophages. Transmission of the organism has been observed by transfusion of infected blood from asymptomatic donors to immunocompromised recipients, leading to clinically apparent disease. There is no licensed Leishmania screening test currently available. Materials and Methods  This study investigated the potential for a novel DNA-intercalating photosensitizer, thiopyrylium (TP), to inactivate Leishmania donovani infantum in red cell (RBC) suspensions. Results  A 5·7 TCID50 reduction of Leishmania was observed in samples treated with 12·5 µmole l−1 TP and 1·1 J cm−2 light. Conclusions Leishmania is highly sensitive to photoinactivation under conditions that have been previously demonstrated to maintain RBC properties during 42 days of storage.