Babesiosis is a “tick-borne zoonosis caused by infections with intra-erythrocytic protozoa of the genus
Babesia” that can be transmitted from an infected donor through transfusion of blood products and solid organ transplantation. The highest prevalence is reported in the United States with the majority of cases caused by
B. microti (prevalent in the Northeast and upper Midwest). Other
Babesia species and related organisms are implicated in transmission of
Babesia in several western US states.
The vast majority of
B. microti infections are asymptomatic and never diagnosed. The parasitemic period for
B. microti is reported to last from 2 to 7 months but may persist for more than 2 years. Transfusion-transmitted infections are reported year-round for
B. microti. Transfusion of blood products collected from asymptomatic donors may result in transmission of the infection and potentially fatal clinical illness in blood transfusion recipients.
The AABB Association Bulletin #14-05 provides risk mitigation measures and other information to address Babesiosis in the absence of recommendations from FDA. In the
July 2018 draft guidance, FDA stated that the agency “has determined that babesiosis is a transfusion-transmitted infection (TTI) under 21 CFR 630.3(l) and a relevant TTI (RTTI) under 21 CFR 630.3(h)(2). This determination is based on the severity of the disease, confirmed transfusion-transmission by blood and blood components, the availability of appropriate screening measures and donor screening tests and significant incidence and prevalence affecting the potential donor population.” The agency “has considered the BPAC discussion and determined that limiting donation testing to states with
Babesia risk but requiring both NAT and antibody testing year-round in those states, is a preferred strategy that balances risk reduction with the scope of testing.” The agency will consider comments to the docket when drafting final recommendations. Section VII. of the draft guidance, TESTING PRIOR TO PUBLICATION OF THE FINAL GUIDANCE, provides important information for those pursuing early implementation of testing.
AABB works closely with the
Centers for Disease Control and Prevention, and the
Council of State and Territorial Epidemiologists to assess the latest scientific information and develop appropriate tools and policies to reduce the risk of transfusion-transmitted
B. microti infection.