Des Vignes F, Levin M L, Fish D
Department of Epidemiology and Public Health, Yale School of Medicine, New Haven, CT 06520-8034, USA.
J Med Entomol. 1999 Mar;36(2):182-5. doi: 10.1093/jmedent/36.2.182.
Vector competence of Ixodes scapularis Say and Dermacentor variabilis Say for the agent of human granulocytic ehrlichiosis (HGE) was compared. Five white-footed mice, Peromyscus leucopus Rafinesque, were inoculated intra-peritoneally with blood from a mouse infected with the agent of HGE. Approximately 100 I. scapularis and D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Fed larvae were collected, separated according to species and allowed to molt to nymphs. Twenty-six per cent of I. scapularis (34/131) and 11% of D. variabilis (11/96) tested positive for the agent of HGE by polymerase chain reaction (PCR) after molting to nymphs. Positive I. scapularis nymphs transmitted the agent of HGE to P. leucopus mice in 5 of 5 trials. In contrast, the positive D. variabilis nymphs did not transmit the agent of agent of HGE in any of 6 trials. In a 2nd experiment, 3 P. leucopus mice were infested with I. scapularis nymphs that were infected with the agent of HGE. All 3 mice became infected with the agent of HGE and approximately 300 D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Larvae were collected and allowed to molt to nymphs as before. Approximately 8% (5/60) of the nymphs became positive for the agent of HGE as determined by PCR. Twenty-five of these nymphs were then placed on each of 9 P. leucopus mice and allowed to feed to repletion. Evidence of transmission was not observed in any of 9 mice exposed to D. variabilis nymphs. These results demonstrate that although I. scapularis is a competent vector of the agent of the HGF, D. variabilis is not.
对肩突硬蜱（Ixodes scapularis Say）和变异革蜱（Dermacentor variabilis Say）作为人粒细胞埃立克体病（HGE）病原体传播媒介的能力进行了比较。将5只白足鼠（白足鼠属，Peromyscus leucopus Rafinesque）经腹腔接种感染了HGE病原体的小鼠血液。在每只小鼠身上放置约100只肩突硬蜱和变异革蜱幼虫，让其饱食。收集饱食后的幼虫，按种类分开，使其蜕皮为若虫。肩突硬蜱若虫中有26%（34/131）、变异革蜱若虫中有11%（11/96）在蜕皮为若虫后通过聚合酶链反应（PCR）检测HGE病原体呈阳性。5次试验中，5只感染了HGE病原体的肩突硬蜱若虫将病原体传播给了白足鼠。相比之下，6次试验中，变异革蜱阳性若虫在任何一次试验中均未传播HGE病原体。在第二个实验中，3只白足鼠感染了感染HGE病原体的肩突硬蜱若虫。所有3只小鼠均感染了HGE病原体，然后在每只小鼠身上放置约300只变异革蜱幼虫，让其饱食。收集幼虫，像之前一样让其蜕皮为若虫。通过PCR测定，约8%（5/60）的若虫HGE病原体检测呈阳性。然后将其中25只若虫分别放在9只白足鼠身上，让其饱食。暴露于变异革蜱若虫的9只小鼠中，任何一只均未观察到传播证据。这些结果表明，虽然肩突硬蜱是HGE病原体的有效传播媒介，但变异革蜱不是。
