The 58-year-old female patient was a farmer from Yuanzhou District, Yichun City, Jiangxi Province. The patient underwent radical pancreaticoduodenectomy for cholangiocarcinoma in the Second People’s Hospital of Yichun City on June 4, 2023 due to postoperative intra-abdominal hemorrhage. After blood transfusion and other treatments, the active hemorrhage remained. She underwent cesarean section on June 9, with recurrent abdominal pains after the operation. She had symptoms of vomiting and fever with the highest temperature of 40 ℃ in the middle and late July. The patient was transferred to the Second Affiliated Hospital of Nanchang University with “abdominal infection” diagnosis on August 13. Laboratory tests showed the red blood cell count was 1.75 × 10¹²/L and the hemoglobin was 49 g/L, which suggested severe anemia. The total protein was 60.5 g/L and the albumin was 31.4 g/L, which suggested hypoproteinemia. The patient also had mildly elevated total, direct and indirect bilirubin. Abdominal CT examination showed splenomegaly, splenic multiple infarct foci. Cranial diffusion imaging examination showed multiple infarct foci in the center of the bilateral semiovals and the lateral paraventricular region. Giemsa stained blood smear on August 15 showed ring-form parasites in some red blood cells, and parasitic infections were considered. The patient has been living in the rural area of Yuanzhou District for a long time without domestic or overseas-traveling history, and no clear history of tick bites before the onset of the disease. The DNA extracted from blood samples of August 17 and 18 was amplificated uesd Babesia spp. specific primer by PCR and sequenced to identify 18S rRNA gene fragment. The PCR product identified with 99.57% homology to B. microti (GenBank: JX962781.1). The diagnosis of Babesia microti infection was confirmed. The patient was treated with oral clindamycin 0.45 g, 3 times per day for 5 days, and the symptoms were relieved. On September 30, parasites were still detected on microscopic examination. The patient was treated with doxycycline hydrochloride injection 0.1 g per day for 3 days, followed by doxycycline hydrochloride tablets 0.1 g, 2 times per day for 15 days. At follow-up on October 30, the patient had only a slight tremor in the upper limb.