AUTHOR=Cai Yuchun , Xu Bin , Liu Xiufeng , Yang Wenwu , Mo Ziran , Zheng Bin , Chen Jiaxu , Hu Wei 

TITLE=Transmission risk evaluation of transfusion blood containing low-density Babesia microti

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1334426

DOI=10.3389/fcimb.2024.1334426

ISSN=2235-2988

ABSTRACT=<sec><title>Background</title><p><italic>Babesia</italic> is a unique apicomplexan parasite that specifically invades and proliferates in red blood cells and can be transmitted via blood transfusion, resulting in transfusion-transmitted babesiosis. However, detecting <italic>Babesia</italic> in blood before transfusion has not received enough attention, and the risk of transfusing blood containing a low density of <italic>Babesia microti</italic> (<italic>B. microti</italic>) is unclear, possibly threatening public health and wellness.</p></sec><sec><title>Purpose</title><p>This study aimed to determine the lower detection limit of <italic>B. microti</italic> in blood and to evaluate the transmission risk of blood transfusion containing low-density <italic>B. microti</italic>.</p></sec><sec><title>Methods</title><p>Infected BALB/c mouse models were established by transfusing infected whole blood with different infection rates and densities of <italic>B. microti</italic>. Microscopic examination, nested Polymerase Chain Reaction (nested PCR), and an enzyme-linked immunosorbent assay (ELISA) were used to evaluate the infection status of the mouse models. Meanwhile, the nested PCR detection limit of <italic>B. microti</italic> was obtained using pure <italic>B. microti</italic> DNA samples with serial concentrations and whole blood samples with different densities of <italic>B. microti</italic>-infected red blood cells. Thereafter, whole mouse blood with a <italic>B. microti</italic> density lower than that of the nested PCR detection limit and human blood samples infected with <italic>B. microti</italic> were transfused into healthy mice to assess the transmission risk in mouse models. The infection status of these mice was evaluated through microscopic examination, nested PCR tests, and ELISA.</p></sec><sec><title>Results</title><p>The mice inoculated with different densities of <italic>B. microti</italic> reached the peak infection rate on different days. Overall, the higher the blood <italic>B. microti</italic> density was, the earlier the peak infection rate was reached. The levels of specific antibodies against <italic>B. microti</italic> in the blood of the infected mice increased sharply during the first 30 days of infection, reaching a peak level at 60 days post-infection, and maintaining a high level thereafter. The nested PCR detection limits of <italic>B. microti</italic> DNA and parasite density were 3 fg and 5.48 parasites/μL, respectively. The whole blood containing an extremely low density of <italic>B. microti</italic> and human blood samples infected with <italic>B. microti</italic> could infect mice, confirming the transmission risk of transfusing blood with low-density <italic>B. microti</italic>.</p></sec><sec><title>Conclusion</title><p>Whole blood containing extremely low density of <italic>B. microti</italic> poses a high transmission risk when transfused between mice and mice or human and mice, suggesting that <italic>Babesia</italic> detection should be considered by governments, hospitals, and disease prevention and control centers as a mandatory test before blood donation or transfusion.</p></sec>