Background/Case Studies: TTM remains a blood safety concern in United States and globally. Malaria risk deferral policies are important for mitigating the risk of TTM and apply to all transfusable components, including plasma for transfusion. While red blood cells (RBC) and platelet are demonstrated to be the primary source of TTM, there have been rare reports of transmission via transfusion of plasma isolated from infected donors. We performed a systematic study to determine the duration of Plasmodium falciparum parasite survival in human plasma when stored under different temperatures.
Study
Design/Methods: We spiked donor plasma collected in citrate-phosphate-dextrose with P. falciparum (3D7 strain) asexual ring stage parasites at low levels of parasitemia (0.25%) and RBC contamination (~10,000/µl). Spiked plasma samples were stored at room temperature, refrigerated (+4˚C), and frozen (-20˚C and -80˚C) and duration of survival at different conditions was determined by assessment of infectivity in a human red cell culture system.
Results/Findings: P. falciparum parasites were viable at all storage conditions in plasma after 1 day of storage based on ability to replicate in cultures. After 7 days of storage, parasites were not viable at refrigerated conditions, or frozen to -20˚C, but remained viable when stored at room temperature or at -80˚C. At – 80˚C, infectious parasites could be detected up to 180 days, which was the longest timepoint assessed in the study. Conclusions: The results demonstrate that P. falciparum can survive for different durations in refrigerated or frozen plasma containing low levels of contaminating RBC. While a loss of viability was seen in prolonged refrigeration and -20˚C, storage at -80˚C maintained parasite viability for at least for 180 days period. Our results support FDA’s current recommendations for donor deferral and component retrieval to reduce the risk of TTM.
Importance of research: We, for the first time, provide laboratory data on duration of survival of Plasmodium falciparum parasites in human plasma when stored at different temperatures. Results from this study provide a scientific basis to reduce the risk of transfusion-transmitted malaria (TTM) and support FDA’s current recommendations for donor deferral and retrieval of blood components intended for transfusion.
