Transcription-mediated amplification blood donation screening for Babesia.

BACKGROUND: Transfusion-transmitted Babesia microti is well recognized in the Northeast and upper Midwestern United States. Blood donation screening in Babesia-endemic states has occurred under investigational protocols prior to US Food and Drug Administration-licensed test availability. Here, we provide a prospective screening summary of nucleic acid testing (NAT) as part of a multicenter Babesia pivotal trial followed by extended investigational use. METHODS: From June 2017 to February 2018, 176,928 donation samples were tested with Procleix Babesia Assay (Grifols Diagnostic Solutions), a blood screening NAT for Babesia species ribosomal RNA detection using whole blood samples. During the pivotal trial, donations were collected in 11 endemic states plus Washington, DC, and Florida (nonendemic). Whole blood lysate samples were either tested in pools of 16 or individually. Reactive samples were confirmed by Babesia microti antibody and polymerase chain reaction (PCR) testing. If unconfirmed, further testing used a second PCR assay capable of detecting multiple Babesia species. Follow-up samples were also tested. Extended investigational testing followed pivotal trial completion. RESULTS: The pivotal trial identified 61 confirmed positives (176,608 donations): 35 (57%) PCR positive, 59 (97%) antibody positive, and two (3%) NAT positive/antibody negative, for a total yield of one positive per 2895 donations, including one Florida resident; others were from seven endemic states. During extended investigational testing of 496,270 donations in endemic states through January 2019, 211 (1:2351) repeat reactive donations were identified. CONCLUSIONS: Babesia was detected in donors from multiple US states, including one previously not associated with positive blood donors. This study supports the use of the Procleix Babesia Assay using individual testing or pools of up to 16.

The impact of Babesia microti blood donation screening.

BACKGROUND: Babesia microti, an intraerythrocytic parasite endemic in the Northeast and upper Midwest United States, is responsible for over 200 reported cases of transfusion-transmitted babesiosis (TTB). The American Red Cross has prospectively screened donations in endemic areas for B. microti since 2012. METHODS: Blood donation samples from Massachusetts, Connecticut, Minnesota, and Wisconsin were tested by arrayed fluorescence immunoassay and real-time polymerase chain reaction. Donors with reactive results by any test were deferred and invited to participate in a follow-up study. RESULTS: Screening of 506,540 donations (June 2012-May 2018) yielded 1299 reactives, 177 of which were DNA and antibody positive and 25 DNA positive only. During the same time, 23 unscreened RBC units collected in Connecticut and Massachusetts were involved in TTB cases, making the risk of transmitting the infection from an unscreened donation in these two states 15.6-times greater than from a Babesia-negative unit. B. microti screening in Connecticut and Massachusetts has been associated with a reduction in TTB cases; none reported from blood donors residing in Connecticut since 2016. The positive donor rate has also decreased in Connecticut from 0.67% in 2013 to 0.23% in 2017. Ongoing follow-up testing has shown that only 10% of antibody-positive donors serorevert within 1 year, while 94% of polymerase chain reacton-positive donors become negative within 12 months. CONCLUSIONS: Blood donation screening for B. microti in endemic areas effectively mitigates TTB risk. Screening should be considered for all areas demonstrating ongoing risk defined as clinical cases or positive blood donors including those associated with TTB cases.

Babesia microti seroprevalence in Minnesota blood donors.

BACKGROUND: The increasing frequency of transfusion-transmitted babesiosis represents a concern for the safety of the US blood supply. The agent responsible for the disease, the intraerythrocytic parasite Babesia microti, is naturally transmitted to humans by a tick bite and is endemic in areas of the Northeast and Upper Midwest United States. In this study, we explored B. microti seroprevalence in blood donors from different areas of Minnesota (MN). STUDY DESIGN AND METHODS: We tested 2150 blood donors in MN for the presence of antibodies against B. microti using an immunofluorescent assay (IFA). Donors identified as positive (≥64) were also tested by real-time polymerase chain reaction (PCR) for the presence of parasite DNA. Seropositive donors were contacted by phone and asked questions regarding tick exposure. Donors positive by IFA were indefinitely deferred from donating blood. RESULTS: A total of 2150 donations were tested between October 2010 and November 2011. Forty-two donors (2.0%) were positive by IFA and one was also PCR positive. All positive donors reported extended outdoor activities, 12 recalled finding ticks on their body, and six had flu-like symptoms since their last blood draw. CONCLUSIONS: This study provides new data about B. microti seroprevalence in MN blood donors. Possibly because the targeted collection areas were mostly expected to be endemic for the parasite, the observed seroprevalence levels were higher than expected, although the geographic distribution of positive donors did not completely overlap with the distribution of reported clinical cases in MN.