Investigational screening for Babesia microti in a large repository of blood donor samples from nonendemic and endemic areas of the United States

Abstract

B. microti prevalence followed expected geographical patterns. Screening was feasible with a performance comparable or superior to other infectious disease blood donor screening assays.

Molecular Diagnostics in the Diagnosis of Parasitic Infection

“…It is also useful when morphology is suboptimal due to specimen age, prolonged exposure to EDTA and patient receipt of anti-babesial drugs. Finally, PCR may be useful for screening cases where the parasite load is low, such as for blood donor screening in endemic settings (Moritz et al, 2014;Young et al, 2012). The American Red Cross recently completed an investigational study using both an indirect immunofluorescence assay and PCR for screening blood donor units obtained in highly endemic states for babesiosis and found this approach to be feasible and cost-effective (Susan Stramer, personal communication, American Red Cross).…”

Transfusion-transmitted babesiosis: is it time to screen the blood supply?

“…Secondly, people who have cleared a B. microti infection typically exhibit a measurable antibody titer lasting for months and sometimes years [6,30]. In endemic populations, the majority of seropositive individuals have been found to be PCR negative and thus are most likely to represent prior rather than active infections [34,35]. These individuals pose little or no risk to blood safety but would be subject to deferral based on detection of B. microti antibody.…”

“…A subsequent study by Moritz et al under IND consisted of parallel testing by immunofluorescence and PCR assays of 13,269 paired plasma and whole blood samples from donors in endemic (MN, WI, MA, CT) and non-endemic (AZ, OK) regions [34]. The immunofluorescence assay, an automated version termed AFIA, yielded a 0.75% seropositivity rate in an endemic region comprising MA and CT. Five of 38 (13%) seropositive samples in this group were also positive by PCR and hence potentially infectious.…”

“…In the study by Moritz et al, all donors were tested by PCR in parallel with the immunofluorescence (AFIA) serological method. Results showed no PCR-positive donors among the AFIA-negative group [34]. A subsequent report from the same group described results of ongoing screening in which a total of 84,209 donors in endemic regions of CT, MA, MN and WI had been tested by AFIA and PCR.…”

“… * after exclusion of confirmed positives Note: The sensitivity of the IFA (AFIA) assay for detection of PCR-positive patients with symptoms of babesiosis was reported as 81.6%, with non-detected cases presumed to be in the window period[34]. The sensitivity of the ELISA assay for PCR or blood smear positive patients with symptoms of babesiosis was 78.3%[35].…”