Persing D H, Herwaldt B L, Glaser C, Lane R S, Thomford J W, Mathiesen D, Krause P J, Phillip D F, Conrad P A
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905.
N Engl J Med. 1995 Feb 2;332(5):298-303. doi: 10.1056/NEJM199502023320504.
Human babesiosis is a tick-transmitted zoonosis associated with two protozoa of the family Piroplasmorida: Babesia microti (in the United States) and B. divergens (in Europe). Recently, infection with an unusual babesia-like piroplasm (designated WA1) was described in a patient from Washington State. We studied four patients in California who were identified as being infected with a similar protozoal parasite. All four patients had undergone splenectomy, three because of trauma and one because of Hodgkin's disease. Two of the patients had complicated courses, and one died.
Piroplasm-specific nuclear small-subunit ribosomal DNA was recovered from the blood of the four patients by amplification with the polymerase chain reaction. The genetic sequences were compared with those of other known piroplasm species. Indirect immunofluorescent-antibody testing of serum from the four patients and from other potentially exposed persons was performed with WA1 and babesia antigens.
Genetic sequence analysis showed that the organisms from all four patients were nearly identical. Phylogenic analysis showed that this strain is more closely related to a known canine pathogen (B. gibsoni) and to theileria species than to some members of the genus babesia. Serum from three of the patients was reactive to WA1 but not to B. microti antigen. Serologic testing showed WA1-antibody seroprevalence rates of 16 percent (8 of 51 persons at risk) and 3.5 percent (4 of 115) in two geographically distinct areas of northern California.
A newly identified babesia-like organism causes infections in humans in the western United States. The clinical spectrum associated with infection with this protozoan ranges from asymptomatic infection or influenza-like illness to fulminant, fatal disease.
人巴贝斯虫病是一种由蜱传播的人畜共患病，与梨浆虫科的两种原生动物有关：微小巴贝斯虫（在美国）和分歧巴贝斯虫（在欧洲）。最近，在一名来自华盛顿州的患者中发现了一种不寻常的类巴贝斯虫梨浆虫（命名为WA1）感染。我们研究了加利福尼亚州的四名被鉴定感染类似原生动物寄生虫的患者。所有四名患者均接受了脾切除术，其中三名因外伤，一名因霍奇金病。两名患者病程复杂，一名死亡。
通过聚合酶链反应扩增从四名患者的血液中回收梨浆虫特异性核小亚基核糖体DNA。将基因序列与其他已知梨浆虫物种进行比较。用WA1和巴贝斯虫抗原对四名患者及其他可能接触者的血清进行间接免疫荧光抗体检测。
基因序列分析表明，所有四名患者的病原体几乎相同。系统发育分析表明，该菌株与已知的犬病原体（吉氏巴贝斯虫）和泰勒虫属的关系比与巴贝斯虫属的一些成员更密切。三名患者的血清对WA1有反应，但对微小巴贝斯虫抗原无反应。血清学检测显示，在加利福尼亚州北部两个地理区域，WA1抗体血清阳性率分别为16%（51名有风险者中的8名）和3.5%（115名中的4名）。
一种新发现的类巴贝斯虫生物在美国西部导致人类感染。与这种原生动物感染相关的临床谱范围从无症状感染或流感样疾病到暴发性、致命性疾病。
