目的 对1例误诊为疟疾的田鼠巴贝虫病患者进行鉴别诊断,并分析其临床诊治情况。方法 收集患者的临床发病资料,对患者进行流行病学调查。采集患者血样,制作厚、薄血片,吉氏染色后镜检,并进行疟疾快速诊断试剂（RDT）检测。提取患者外周血DNA,以巴贝虫18S rRNA基因属、种特异性引物和恶性疟原虫核糖体RNA小亚基(SSU rRNA)基因特异性引物进行PCR扩增。结果 该患者于2019年2月起,反复发热2月余,血常规白细胞、红细胞和血小板进行性下降,有中度贫血及脾肿大。流行病学调查结果显示,该患者无外出史。患者外周血的厚、薄涂片均可见大量似恶性疟原虫虫体,其外周血经疟疾快速诊断试剂检测呈阴性。患者血样DNA经PCR扩增后,可获得长度约400 bp和 1 600 bp的巴贝虫属、田鼠巴贝虫种特异性阳性条带。结论 结合患者的临床发病资料、流行病学史、病原学和分子生物学检测结果,确诊其为田鼠巴贝虫感染。

Objective To perform differential diagnosis of a case of Babesia microti infection earlier misdiagnosed as malaria, and analyze the clinical treatment.Methods Clinical and epidemiological information of the case was collected. Blood sample was collected and examined by microscopy with. Giemsa-stained thick and thin blood smears for observing Babesia morphologically. Peripheral blood sample was also underwent rapid immunological assay for malaria parasite. DNA was extracted from the patient’s blood sample and PCR amplification was performed with genus and species-specific primers of Babesia 18S rRNA gene, and specific primers of Plasmodium falciparum small subunit ribosomal ribonucleic acid (SSU rRNA) gene.Results The patient had recurrent fever for more than 2 months since February 2019, and his blood routine examinations showed progressive decrease of white blood cells, red blood cells, and platelets, with moderate anemia and splenomegaly. Epidemiological investigation showed that the patient had no history of travel out of town. A large number of P. falciparum-like parasites were seen in the thick and thin blood smears of the patient, and and malaria rapid diagnostic assay presented negative result. Using B. microti-specific primers, PCR amplification indicates genus and species-specific positive bands of 400 bp and 1 600 bp length, respectively.Conclusion Combining the clinical information, epidemiological history, etiology and PCR analysis data, the case was diagnosed as B. microti infection.