Rikihisa Y
Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210.
Clin Microbiol Rev. 1991 Jul;4(3):286-308. doi: 10.1128/CMR.4.3.286.
The tribe Ehrlichieae consists of gram-negative minute cocci that are obligate intracellular parasites classified in the family Rickettsiaceae. Although ehrlichial organisms have been observed in leukocytes for many years, only a few species have been cultured in quantities sufficient for biochemical and molecular analyses. Recents studies on 16S-rRNA sequence analysis and energy metabolism showed that the genus Ehrlichia is closely related to the genus Rickettsia. There is, however, no antigenic cross-reactivity between these genera. Ehrlichial organisms cause a disease called "ehrlichiosis," a noncontagious infectious disease known to be transmitted by a tick in several cases and by a fluke in one case. Ehrlichia spp. infect dogs, ruminants, horses, and humans. Recently, two new ehrlichial diseases, Potomac horse fever and human ehrlichiosis, were discovered in the United States. The etiologic agent of Potomac horse fever, Ehrlichia risticii, is closely related to the known human pathogen Ehrlichia sennetsu. The etiologic agent of human ehrlichiosis is related to Ehrlichia canis, a canine pathogen. In contrast to the genus Rickettsia, members of the tribe Ehrlichieae reside primarily in the cytoplasmic vacuoles of monocytes or granulocytes and cause hematologic abnormalities, lymphadenopathy, and other pathologic changes in the host. However, the actual mechanisms whereby Ehrlichia spp. infect leukocytes, multiply in them, and produce various forms of systemic disease have not been defined. Depending on the ehrlichial species involved, serologic or direct microscopic observation of stained blood smears is currently used to diagnose ehrlichial disease.
埃立克体族由革兰氏阴性微小球菌组成，它们是专性细胞内寄生虫，归类于立克次氏体科。尽管多年来已在白细胞中观察到埃立克体微生物，但只有少数几种已培养到足以进行生化和分子分析的数量。最近关于16S - rRNA序列分析和能量代谢的研究表明，埃立克体属与立克次体属密切相关。然而，这些属之间没有抗原交叉反应。埃立克体微生物引起一种称为“埃立克体病”的疾病，这是一种非传染性传染病，已知在某些情况下由蜱传播，在一例中由吸虫传播。埃立克体属感染犬、反刍动物、马和人类。最近，在美国发现了两种新的埃立克体病，即波托马克马热和人类埃立克体病。波托马克马热的病原体里氏埃立克体与已知的人类病原体嗜人类埃立克体密切相关。人类埃立克体病的病原体与犬埃立克体有关，犬埃立克体是一种犬病原体。与立克次体属不同，埃立克体族的成员主要存在于单核细胞或粒细胞的细胞质空泡中，并在宿主中引起血液学异常、淋巴结病和其他病理变化。然而，埃立克体属感染白细胞、在其中繁殖并产生各种形式的全身性疾病的实际机制尚未明确。根据所涉及的埃立克体种类，目前使用血清学或对染色血涂片进行直接显微镜观察来诊断埃立克体病。
