Riboflavin and ultraviolet light reduce the infectivity of Babesia microti in whole blood

Authors

  • Laura Tonnetti,

    Corresponding author
    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • Aaron M. Thorp,

    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • Heather L. Reddy,

    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • Shawn D. Keil,

    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • Raymond P. Goodrich,

    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • David A. Leiby

    1. From the Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland; and CaridianBCT Biotechnologies, LLC, Lakewood, Colorado.
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  • Financial support: CaridianBCT Biotechnologies, LLC, DOD Grant W81XWH-09-2-0100. The U.S. Army Medical Research Acquisition Activity (Fort Detrick, MD) is the awarding and administering acquisition office.

  • The content of the information contained herein does not necessarily reflect the position or the policy of the government and no official endorsement should be inferred.

Laura Tonnetti, PhD, Transmissible Diseases Department, American Red Cross Holland Laboratory, 15601 Crabbs Branch Way, Rockville, MD 20855; e-mail: Laura.Tonnetti@redcross.org.

Abstract

BACKGROUND: Babesia microti is the parasite most frequently transmitted by blood transfusion in the United States. Previous work demonstrated the efficacy of riboflavin (RB) and ultraviolet (UV) light to inactivate B. microti in apheresis plasma and platelet units. In this study we investigated the effectiveness of RB and UV light to reduce the levels of B. microti in whole blood (WB).

STUDY DESIGN AND METHODS: WB units were spiked with B. microti-infected hamster blood. Spearman-Karber methods were used to calculate infectivity of each sample in terms of hamster infectious dose 50% (HID50) value. After RB addition, the units were illuminated with 80 J/mLRBC UV light. Two samples were collected: one before illumination and one after illumination. The samples were serially diluted and dilutions injected into a group of five naive hamsters. Four weeks postinoculation (PI), blood was collected from the animals and evaluated by microscopic observation.

RESULTS: One pilot study showed a good dose response in the animals and demonstrated that sample infectivity could be calculated in terms of an HID50. Three additional replicates were performed in the same manner as the pilot study, but with fewer dilutions. Infectivity values were consistent between the experiments and were used to calculate log reduction. The posttreatment reduction of B. microti for all the experiments was more than 5 log.

CONCLUSIONS: The data collected indicate that use of RB and UV is able to decrease the parasite load in WB units thus reducing the risk of transfusion-transmitted B. microti from blood components containing B. microti-infected RBCs.

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