title: A case of human infection with a novel Babesia species in China.
abstract: BACKGROUND
  Babesiosis is an uncommon but emerging tick-borne disease caused by the genus Babesia. In this case study, we report a case of human infection with a novel Babesia sp. in China.
  
  
  RESULTS
  The patient in question had been suffering from repetitive occurrences of mild fever of unknown origin and fatigue for 10 years. Ring forms, tetrads, and one or two dots of chromatin or trophozoite-like organisms were observed in the patient's thin blood smears and bone marrow smears. Using a confocal laser-scanning microscope, it was observed that the patient's serum had reactivity with the surface proteins of the B. microti strain. Electron microscopy revealed oval red blood cells with 1 ~ 2 μm of knob protrusions in the cellular membrane. The results of the Babesia-specific nested PCR assay for 18S rRNA confirmed the presence of Babesia infection. The construction of a phylogenetic relationship showed clustering with B. microti and B. duncani, which was identified as a novel Babesia species and named as Babesia sp. XXB/HangZhou. Azithromycin, doxycycline, and moxifloxacin hydrochloride were shown to relieve symptoms but were not as effective after continuous usage. After atovaquone (Mepron®) administration, the patient recovered from fever and tested negative for detection of Babesia-specific genes.
  
  
  CONCLUSIONS
  Babesia sp. XXB/HangZhou is a novel Babesia species, which causes mild babesiosis in an immunocompetent patient.
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China.
authors.forename: Su-Qin
authors.initials: SQ
authors.lastname: Man
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Qiao
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Feng
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China. yffu@fudan.edu.cn.
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Fu
authors.affiliation: Department of Medical Microbiology and Parasitology, Fudan University School of Medicine, Shanghai, 200032, China.|Institute of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
authors.forename: Xun-Jia
authors.initials: XJ
authors.lastname: Cheng
mesh_terms: D000328:Adult; D001403:Babesia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001404:Babesiosis / Q000175:diagnosis / Q000469:parasitology*; D002681:China; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny
keywords: Babesia sp.; Babesiosis; Tick-borne zoonosis