Background and Objectives  Leishmania is transmitted by the bite of the phlebotomine sandfly or by transfusion of infected blood products. Leishmaniasis currently poses a significant problem in several parts of the world, and is an emerging problem in others. The Mirasol PRT technology is based on the use of riboflavin and ultraviolet light to generate chemical reactions in the nucleic acids of pathogens, which prevents replication and leads to inactivation. The intent of this study was to examine the ability of the Mirasol PRT System to kill the Leishmania parasite in human plasma and platelet concentrates. Materials and Methods  In visceral Leishmaniasis, amastigotes are present in the blood and in the reticuloendothelial system within monocytes. For each unit of plasma or platelets treated, isolated mononuclear cells obtained from 100 ml of normal donor whole blood were incubated with 1·0 × 108Leishmania donovani infantum promastigotes to produce amastigote‐laden macrophages. The infected macrophages were added to 250 ml of human plasma or to 250 ml of platelet concentrates. Infected units were cultured pretreatment in 10‐fold serial dilutions to determine the limits of detection. Thirty millilitres of 500 µm riboflavin was added to each unit, which was then illuminated with 5·9 J/cm2 of ultraviolet light (6·24 J/ml). After treatment and after 2 months of frozen storage, plasma units were cultured in 10‐fold serial dilutions. Platelets were cultured on the day of treatment and on day 5 of storage post‐illumination. Results  A 5 log reduction of Leishmania was demonstrated in five of six units of plasma, and a 7 log reduction of Leishmania was demonstrated in one plasma unit. A 5 log reduction of Leishmania was demonstrated in five of six units of platelets, and a 6 log reduction of Leishmania was demonstrated in one unit. Conclusions  There is no donor screen for Leishmania and other pathogens constantly emerging in our blood supply. The Mirasol PRT System for Platelets and Plasma is an effective means of killing Leishmania and other emerging pathogens in these blood products.

Mirasol PRT treatment demonstrated an ability to inactivate 5-7 logs of T. cruzi in plasma and platelets.

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Riboflavin and light are effective in reducing O. tsutsugamushi. Mice injected with blood products inoculated with 10(5) organisms and treated with riboflavin and light did not experience any signs or symptoms of infection, 17 days after inoculation. A 5-log reduction of this organism in blood was achieved as assayed in an animal model.