Little S E, Stallknecht D E, Lockhart J M, Dawson J E, Davidson W R
Department of Medical Microbiology and Parasitology, College of Veterinary Medicine, The University of Georgia, Athens, 30602, USA.
J Parasitol. 1998 Oct;84(5):897-901.
The ticks Amblyomma americanum and Ixodes scapularis, strongly implicated vectors of Ehrlichia chaffeensis and the human granulocytic ehrlichiosis (HGE) agent, respectively, commonly are found on white-tailed deer (Odocoileus virginianus). As deer can be infected with E. chaffeensis, the HGE agent, and another Ehrlichia-like organism, a deer population parasitized by both tick species in coastal Georgia was tested for evidence of Ehrlichia spp. infection using serologic, molecular, and culture techniques. Antibodies to both E. chaffeensis (geometric mean titer = 111) and Ehrlichia equi, surrogate antigen for the HGE agent, (geometric mean titer = 1,024) were detected by indirect fluorescent antibody testing. Nested polymerase chain reaction employing species-specific primers demonstrated sequence-confirmed 16S rDNA fragments of 3 distinct Ehrlichia spp. in this population: E. chaffeensis (1/5), the HGE agent (3/5), and an Ehrlichia-like organism previously described from white-tailed deer (5/5). Ehrlichia chaffeensis was isolated in culture from the inguinal lymph node of a single deer. An Ehrlichia-type morula was identified in a neutrophil of 1 deer on examination of blood smears. This work provides the first evidence of the HGE agent in a nonhuman host in the southeastern United States and documents infection with both E. chaffeensis and the HGE agent in a single deer population, thereby supporting the importance of white-tailed deer in the natural history of the human ehrlichioses agents.
美洲钝眼蜱和肩突硬蜱分别被强烈怀疑是恰菲埃立克体和人类粒细胞埃立克体病（HGE）病原体的传播媒介，它们常见于白尾鹿（弗吉尼亚鹿）身上。由于鹿可能感染恰菲埃立克体、HGE病原体以及另一种类埃立克体生物，因此对佐治亚州沿海地区被这两种蜱虫寄生的鹿群进行了检测，采用血清学、分子生物学和培养技术来寻找埃立克体属感染的证据。通过间接荧光抗体检测发现了针对恰菲埃立克体（几何平均滴度 = 111）和作为HGE病原体替代抗原的马埃立克体（几何平均滴度 = 1,024）的抗体。使用种特异性引物的巢式聚合酶链反应证明，该鹿群中存在3种不同埃立克体属的经序列确认的16S rDNA片段：恰菲埃立克体（1/5）、HGE病原体（3/5）以及先前在白尾鹿中描述过的一种类埃立克体生物（5/5）。从一只鹿的腹股沟淋巴结中培养分离出了恰菲埃立克体。在检查血涂片时，在1只鹿的中性粒细胞中发现了埃立克体样桑葚体。这项工作提供了美国东南部非人类宿主中存在HGE病原体的首个证据，并记录了单个鹿群同时感染恰菲埃立克体和HGE病原体的情况，从而支持了白尾鹿在人类埃立克体病病原体自然史中的重要性。
