Mukherjee Nabanita, Beati Lorenza, Sellers Michael, Burton Laquita, Adamson Steven, Robbins Richard G, Moore Frank, Karim Shahid
Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA.
Institute of Coastal Plain Sciences, Georgia Southern University, Statesboro, GA 30458, USA.
Ticks Tick Borne Dis. 2014 Mar;5(2):127-34. doi: 10.1016/j.ttbdis.2013.09.009. Epub 2013 Nov 16.
Birds are capable of carrying ticks and, consequently, tick-transmitted microorganisms over long distances and across geographical barriers such as oceans and deserts. Ticks are hosts for several species of spotted fever group rickettsiae (SFGR), which can be transmitted to vertebrates during blood meals. In this study, the prevalence of this group of rickettsiae was examined in ticks infesting migratory songbirds by using polymerase chain reaction (PCR). During the 2009 and 2010 spring migration season, 2064 northward-migrating passerine songbirds were examined for ticks at Johnson Bayou, Louisiana. A total of 91 ticks was removed from 35 individual songbirds for tick species identification and spotted fever group rickettsia detection. Ticks were identified as Haemaphysalis juxtakochi (n=38, 42%), Amblyomma longirostre (n=22, 24%), Amblyomma nodosum (n=17, 19%), Amblyomma calcaratum (n=11, 12%), Amblyomma maculatum (n=2, 2%), and Haemaphysalis leporispalustris (n=1, 1%) by comparing their 12S rDNA gene sequence to homologous sequences in GenBank. Most of the identified ticks were exotic species originating outside of the United States. The phylogenetic analysis of the 71 ompA gene sequences of the rickettsial strains detected in the ticks revealed the occurrence of 6 distinct rickettsial genotypes. Two genotypes (corresponding to a total of 28 samples) were included in the Candidatus Rickettsia amblyommii clade (less than 1% divergence), 2 of them (corresponding to a total of 14 samples) clustered with Rickettsia sp. "Argentina" with less than 0.2% sequence divergence, and 2 of them (corresponding to a total of 27 samples), although closely related to the R. parkeri-R. africae lineage (2.50-3.41% divergence), exhibited sufficient genetic divergence from its members to possibly constitute a new rickettsial genotype. Overall, there does not seem to be a specific relationship between exotic tick species, the rickettsiae they harbor, or the reservoir competence of the corresponding bird species.
鸟类能够携带蜱虫，进而将蜱虫传播的微生物远距离传播，并跨越海洋和沙漠等地理屏障。蜱虫是几种斑点热群立克次氏体（SFGR）的宿主，这些立克次氏体可在蜱虫吸血时传播给脊椎动物。在本研究中，通过聚合酶链反应（PCR）检测了侵袭候鸟的蜱虫中该群立克次氏体的流行情况。在2009年和2010年春季迁徙季节，在路易斯安那州的约翰逊河口对2064只向北迁徙的雀形目鸣禽进行了蜱虫检查。从35只个体鸣禽身上共采集了91只蜱虫，用于蜱虫种类鉴定和斑点热群立克次氏体检测。通过将蜱虫的12S rDNA基因序列与GenBank中的同源序列进行比较，蜱虫被鉴定为近科赫血蜱（n = 38，42%）、长角花蜱（n = 22，24%）、结节花蜱（n = 17，19%）、距刺花蜱（n = 11，12%）、黄斑花蜱（n = 2，2%）和沼泽兔血蜱（n = 1，1%）。大多数鉴定出的蜱虫是原产于美国境外的外来物种。对蜱虫中检测到的立克次氏体菌株的71个ompA基因序列进行系统发育分析，发现有6种不同的立克次氏体基因型。两种基因型（共28个样本）属于候选立克次氏体安氏亚种分支（差异小于1%），其中2个（共14个样本）与立克次氏体“阿根廷种”聚类，序列差异小于0.2%，另外2个（共27个样本）虽然与帕克立克次氏体-非洲立克次氏体谱系密切相关（差异为2.50 - 3.41%），但其与该谱系成员的遗传差异足以可能构成一种新的立克次氏体基因型。总体而言，外来蜱虫种类、它们携带的立克次氏体或相应鸟类物种的储存宿主能力之间似乎没有特定关系。
