Scientific Affairs, American Red Cross, Rockville and Gaithersburg, Maryland.
Transfusion. 2019 Sep;59(9):2908-2912. doi: 10.1111/trf.15425. Epub 2019 Jun 27.
Babesia microti, a red blood cell (RBC) parasite transmitted naturally to vertebrate hosts by ixodid ticks, is endemic to the northeastern and upper midwestern United States, with the geographic range of infected ticks expanding. B. microti is a blood safety issue with >200 transfusion-transmissions reported.
The American Red Cross's Hemovigilance program investigated hospital-reported transfusion-transmitted babesiosis (TTB) cases. Follow-up samples from involved donors were tested for B. microti antibodies and parasite DNA, the latter by real-time polymerase chain reaction (PCR). Test-positive donors were permanently deferred from future donations.
B. microti-positive donors were implicated in 77 of 143 suspect TTB cases investigated from 2010 through 2017. In four cases, two positive donors were identified for a total of 81 positive donors. In three cases, a RBC unit was split and components transfused multiple times to the same pediatric recipient. RBCs were the transmitting product in all cases. At follow-up, all involved donors were antibody positive; 25 donors were also PCR positive. Positive donations were collected throughout the year, peaking in the summer. Most donors (78) were resident of, or traveled to (2), an endemic state. One donor resided in a non-endemic state without relevant travel history. One fatality listed babesia as a contributing factor. No implicated donation was screened by an investigational protocol.
Babesiosis remains a blood safety issue. Prior to FDA-licensed screening test availability and final FDA Guidance, blood collectors in endemic states investigationally tested none, a portion, or all collections. Future expanded testing will reduce the frequency of TTB cases.
微小巴贝斯虫（Babesia microti）是一种通过硬蜱自然传播给脊椎动物宿主的红细胞（RBC）寄生虫，流行于美国东北部和中西部上部地区，感染蜱的地理范围在不断扩大。微小巴贝斯虫是一个血液安全问题，已有超过 200 例输血传播巴贝斯虫病（TTB）报告。
美国红十字会的血液监测计划调查了医院报告的输血传播巴贝斯虫病（TTB）病例。对涉及的供体进行了后续样本检测，以检测微小巴贝斯虫抗体和寄生虫 DNA，后者通过实时聚合酶链反应（PCR）进行检测。检测阳性的供体将被永久拒绝捐献。
2010 年至 2017 年期间，对调查的 143 例疑似 TTB 病例中的 77 例进行了微小巴贝斯虫阳性供体的牵连。在 4 例中，有 2 例阳性供体，共发现 81 例阳性供体。在 3 例中，一个红细胞单位被分割并多次输注给同一儿科受者。在所有情况下，传播产品均为 RBC。在随访时，所有涉及的供体均为抗体阳性；25 名供体也为 PCR 阳性。阳性供体在全年均有采集，夏季达到高峰。大多数供体（78 名）来自或前往（2 名）流行地区。一名供体来自非流行地区且无相关旅行史。一名死亡病例将巴贝斯虫列为一个促成因素。没有受感染的供体通过研究性方案进行筛查。
巴贝斯虫病仍然是一个血液安全问题。在 FDA 许可的筛查试验可用和最终 FDA 指南发布之前，流行地区的血液采集者调查性地检测了部分或全部采集物，均未检测微小巴贝斯虫。未来扩大检测将减少 TTB 病例的发生频率。
