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


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.
Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, MD 20855, USA. Laura.Tonnetti@redcross.org
Laura
L
Tonnetti
Aaron M
AM
Thorp
Heather L
HL
Reddy
Shawn D
SD
Keil
Raymond P
RP
Goodrich
David A
DA
Leiby
D000818:Animals; D041001:Babesia microti / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000528:radiation effects*; D001404:Babesiosis / Q000517:prevention & control / Q000635:transmission; D001769:Blood / Q000469:parasitology*; D058731:Blood Safety / Q000379:methods*; D006224:Cricetinae; D016054:DNA, Protozoan / Q000032:analysis; D005260:Female; D006801:Humans; D059208:Parasite Load; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D060888:Real-Time Polymerase Chain Reaction; D012256:Riboflavin / Q000008:administration & dosage*; D065227:Transfusion Reaction; D014466:Ultraviolet Rays
D016054:DNA, Protozoan; D017319:Photosensitizing Agents; D012256:Riboflavin