Background Relapsing babesiosis often occurs in highly immunocompromised patients and has been attributed to the acquisition of resistance against drugs commonly used for treatment such as atovaquone, azithromycin, and clindamycin. Tafenoquine, which is approved for malaria prophylaxis and presumptive antirelapse treatment of Plasmodium vivax malaria, has shown activity against Babesia microti in several animal models of acute infection and in a single human case of relapsing babesiosis. Here, we report 5 cases of relapsing babesiosis treated with tafenoquine, including the previous case, and begin to define the conditions for optimal use of tafenoquine in relapsing babesiosis. Methods A definitive diagnosis of babesiosis was made by microscopic examination of Giemsa-stained thin blood smears or a real-time polymerase chain reaction (PCR) that targets the parasite 18S rRNA gene. Clearance of B. microti infection was ascertained by use of blood smear and real-time PCR. Results Tafenoquine was initiated with a loading dose of 600 mg. A weekly maintenance dose consisted of 200 mg or 300 mg; the lower dose was associated with a delayed clearance of B. microti. In 2 cases, all antimicrobial agents but tafenoquine were discontinued prior to clearance of infection. In 2 other cases, clearance was achieved while tafenoquine was administered along with other antimicrobial agents. In 3 of these 4 cases, tafenoquine was used in combination with atovaquone-proguanil. Other agents included atovaquone, azithromycin, and/or clindamycin. In 1 case, tafenoquine was administered alone and failed to prevent relapse. Conclusions Tafenoquine can be a useful adjunct for the treatment of highly immunocompromised patients experiencing relapsing babesiosis caused by B. microti.

中文翻译：

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他非诺喹治疗复发性巴贝虫病：病例系列


背景 复发性巴贝西虫病通常发生在免疫功能高度低下的患者中，归因于对阿托伐醌、阿奇霉素和克林霉素等常用治疗药物产生耐药性。他非诺喹被批准用于疟疾预防和间日疟原虫疟疾的推定抗复发治疗，在几种急性感染动物模型和一例复发性巴贝西虫病人类病例中显示出对田鼠巴贝虫的活性。在此，我们报告了 5 例用他非诺喹治疗的复发性巴贝西虫病病例，包括之前的病例，并开始确定他非诺喹在复发性巴贝西虫病中最佳使用的条件。方法 通过吉姆萨染色的薄血涂片显微镜检查或针对寄生虫 18S rRNA 基因的实时聚合酶链反应 (PCR) 做出巴贝斯虫病的明确诊断。通过血涂片和实时 PCR 来确定田鼠芽孢杆菌感染的清除情况。结果 他非诺喹起始负荷剂量为 600 mg。每周维持剂量为 200 mg 或 300 mg；较低剂量与田鼠芽孢杆菌的清除延迟有关。在 2 例病例中，在感染清除前停用除他非诺喹外的所有抗菌药物。在另外 2 例病例中，他非诺喹与其他抗菌药物一起使用时实现了清除。在这 4 例病例中，有 3 例是他非诺喹与阿托伐醌-氯胍联合使用。其他药物包括阿托伐醌、阿奇霉素和/或克林霉素。 1例单独服用他非诺喹未能预防复发。结论 他非诺喹可以作为治疗由田鼠巴贝斯虫引起的复发性巴贝斯虫病的高度免疫功能低下患者的有效辅助药物。