Prevalence of Rickettsiales in ticks removed from the skin of outdoor workers in North Carolina
Prevalence of Rickettsiales in ticks removed from the skin of outdoor workers in North Carolina
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DOI：
10.1186/s13071-014-0607-2
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发表时间：
2014-12-23
影响因子：
3.2
通讯作者：
Apperson, Charles S.
中科院分区：
文献类型：
--
作者：
Lee, Sangmi;Kakumanu, Madhavi L.;Apperson, Charles S.
背景资料：蜱传播的立克次体病，如埃立克体病和斑点热立克次体病，是美国南部发病率和死亡率的重要来源。由于暴露在蜱虫出没的林地，户外工作者感染蜱传病原体的风险增加。作为双盲随机对照现场试验的一部分，我们对氯菊酯处理过的衣物在预防蜱虫叮咬方面的有效性进行了研究，我们从北卡罗来纳州的户外工作者皮肤上采集了蜱虫，并对蜱虫进行了立克次体病原体检测。研究参与者在2011年4月至2012年9月提交的蜱虫被鉴定为物种和生命阶段，并通过以17-kDa蛋白基因为靶点的巢式PCR初步筛选立克次体属。通过PCR扩增23 S-5S基因间区（IGS）片段，结合种特异性探针的反向线性印迹杂交，以及23 S-5S扩增子的克隆和核苷酸序列分析，进一步鉴定立克次体属种。通过巢式PCR检测蜱类中的埃立克体和无浆体，该PCR针对gltA、含有可变数目串联重复序列的抗原表达基因、16 S rRNA和groESL基因。结果：2011年（n = 423）和2012年（n = 451）提交的蜱类中，孤星星蜱（Amblyomma americanum）分别占95.0%和92.9%。还鉴定了美洲犬蜱（Dermacentor variabilis）、墨西哥湾沿岸蜱（Amblyomma maculatum）和黑腿蜱（Ixodes scapularis）的标本。在我们研究的两年中，60.9%的蜱虫检测为17 kDa阳性。在所有4种蜱种中鉴定出“安氏立克次体”，占23 S-5S阳性样品的90.2%（416/461），占所有检测样品的52.9%（416/787）。对立克次体特异性23 S-5S IGS、ompA和gltA基因片段的核苷酸序列分析表明，蜱类主要是A. americanum，包含立克次体的新物种。其它立克次体包括埃温氏埃立克体（Ehrlichia ewingii）、E. Chaffeensis、Ehrlichia sp.（Panola Mountain）和嗜吞噬细胞无形体（Anaplasma phagocytophilum）的检出率较低，主要见于A.结论：我们得出结论，在北卡罗来纳州，最常见的立克次体暴露是R。amblyommii携带A.美国。其他立克次体目细菌，包括立克次体的新物种，在A.美国，但与公共卫生有关。
Background: Tick-transmitted rickettsial diseases, such as ehrlichiosis and spotted fever rickettsiosis, are significant sources of morbidity and mortality in the southern United States. Because of their exposure in tick-infested woodlands, outdoor workers experience an increased risk of infection with tick-borne pathogens. As part of a double blind randomized-controlled field trial of the effectiveness of permethrin-treated clothing in preventing tick bites, we identified tick species removed from the skin of outdoor workers in North Carolina and tested the ticks for Rickettsiales pathogens.Methods: Ticks submitted by study participants from April-September 2011 and 2012 were identified to species and life stage, and preliminarily screened for the genus Rickettsia by nested PCR targeting the 17-kDa protein gene. Rickettsia were further identified to species by PCR amplification of 23S-5S intergenic spacer (IGS) fragments combined with reverse line blot hybridization with species-specific probes and through cloning and nucleotide sequence analysis of 23S-5S amplicons. Ticks were examined for Ehrlichia and Anaplasma by nested PCR directed at the gltA, antigen-expressing gene containing a variable number of tandem repeats, 16S rRNA, and groESL genes.Results: The lone star tick (Amblyomma americanum) accounted for 95.0 and 92.9% of ticks submitted in 2011 (n = 423) and 2012 (n = 451), respectively. Specimens of American dog tick (Dermacentor variabilis), Gulf Coast tick (Amblyomma maculatum) and black-legged tick (Ixodes scapularis) were also identified. In both years of our study, 60.9% of ticks tested positive for 17-kDa. "Candidatus Rickettsia amblyommii", identified in all four tick species, accounted for 90.2% (416/461) of the 23S-5S-positive samples and 52.9% (416/787) of all samples tested. Nucleotide sequence analysis of Rickettsia-specific 23S-5S IGS, ompA and gltA gene fragments indicated that ticks, principally A. americanum, contained novel species of Rickettsia. Other Rickettsiales, including Ehrlichia ewingii, E. chaffeensis, Ehrlichia sp. (Panola Mountain), and Anaplasma phagocytophilum, were infrequently identified, principally in A. americanum.Conclusions: We conclude that in North Carolina, the most common rickettsial exposure is to R. amblyommii carried by A. americanum. Other Rickettsiales bacteria, including novel species of Rickettsia, were less frequently detected in A. americanum but are relevant to public health nevertheless.