Molecular Detection of Rickettsia Species Within Ticks (Acari: Ixodidae) Collected from Arkansas United States
Molecular Detection of Rickettsia Species Within Ticks (Acari: Ixodidae) Collected from Arkansas United States
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DOI：
10.1093/jme/tjv027
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发表时间：
2015-05-01
影响因子：
2.1
通讯作者：
Williamson, P. C.
中科院分区：
文献类型：
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作者：
Fryxell, R. T. Trout;Steelman, C. D.;Williamson, P. C.
落基山斑疹热（RMSF）由病原体立克次体引起，是美国最严重和最常报告的立克次体疾病，通常在整个东南部被诊断出来。随着蜱中发现白氏立克次体和其他斑点热组立克次体，报告的RMSF病例是否真的是由立克次体或其他斑点热组立克次体引起的尚不确定。阿肯色州是全国RMSF发病率最高的州之一；为了鉴定阿肯色州的立克次体，采用聚合酶链反应（PCR）对1731只蜱、250只白尾鹿和189只犬进行立克次体gltA、romb和ompA基因的筛选。白尾鹿无阳性，犬2只（1.1%）和蜱502只（29.0%）PCR阳性。PCR阳性的蜱种有5种，分别为美洲钝头蜱244只（37%）、镰形硬尾蜱130只（38%）、斑点钝头蜱65只（39%）、血鼻头蜱30只（9%）、变皮蜱7只（4%）、未知钝头蜱26只（44%）。测序产物均与立克次体无同源性。通过romb扩增，最常见的立克次体是山地立克次体和无致病性的无致病性候鸟立克次体，而通过ompA扩增，最常见的立克次体是无致病性的amblyommii。在阿肯色州西北部收集的许多蜱虫标本均呈PCR阳性，这些蜱虫通常是美洲蜱，携带一种目前非致病性立克次体——跛视蜱。这里报告的数据表明，这些蜱中没有致病性立克次体，并进一步表明，其他SFGR可能是阿肯色州诊断的RMSF病例的病原体。
Rocky Mountain spotted fever (RMSF), caused by the etiological agent Rickettsia rickettsii, is the most severe and frequently reported rickettsial illness in the United States, and is commonly diagnosed throughout the southeast. With the discoveries of Rickettsia parkeri and other spotted fever group rickettsiae (SFGR) in ticks, it remains inconclusive if the cases reported as RMSF are truly caused by R. rickettsii or other SFGR. Arkansas reports one of the highest incidence rates of RMSF in the country; consequently, to identify the rickettsiae in Arkansas, 1,731 ticks, 250 white-tailed deer, and 189 canines were screened by polymerase chain reaction (PCR) for the rickettsial genes gltA, rompB, and ompA. None of the white-tailed deer were positive, while two of the canines (1.1%) and 502 (29.0%) of the ticks were PCR positive. Five different tick species were PCR positive: 244 (37%) Amblyomma americanum L., 130 (38%) Ixodes scapularis Say, 65 (39%) Amblyomma maculatum (Koch), 30 (9%) Rhipicephalus sanguineus Latreille, 7 (4%) Dermacentor variabilis Say, and 26 (44%) unidentified Amblyomma ticks. None of the sequenced products were homologous to R. rickettsii. The most common Rickettsia via rompB amplification was Rickettsia montanensis and nonpathogenic Candidatus Rickettsia amblyommii, whereas with ompA amplification the most common Rickettsia was Ca. R. amblyommii. Many tick specimens collected in northwest Arkansas were PCR positive and these were commonly A. americanum harboring Ca. R. amblyommii, a currently nonpathogenic Rickettsia. Data reported here indicate that pathogenic R. rickettsii was absent from these ticks and suggest by extension that other SFGR are likely the causative agents for Arkansas diagnosed RMSF cases.