巴西東南部硬蜱之分子鑑定及其媒介病原體檢測

Molecular Identification of Hard Ticks and Tick-Borne Pathogens in Southeastern Brazil

Stefanie Hellen Rodrigues Cota(Stefanie Hellen Rodrigues Cota)

指導教授 ： 師健民

高雄醫學大學/醫學院/熱帶醫學碩士學位學程/碩士(2019年)

摘要

研究背景：斑疹熱乃因立克次體(Rickettsia)感染引起，並首次於1929年在巴西報導，由於斑疹熱引發之高度死亡率，因而瞭解何種病媒蜱可以攜帶此致病原是很重要的。巴西這個國家擁有極大生態及物種之多樣性，有關硬蜱之種株變異及其攜帶病原體差異性亦是如此。過去25年來有關立克次體菌株之範疇及重要性，近年研究顯示過去已知非致病性菌株之改變，亦突顯該致病原引起新興及再浮現疾病之複雜性，故而必須運用分子技術規劃相關研究，以有效鑑定硬蜱種株及檢測確認蜱攜帶病原體。
研究目的：本研究目的除鑑定採集自巴西東南部之硬蜱種株，亦將檢測確認這些硬蜱攜帶之立克次體情形。
研究方法：總共自巴西東南部隸屬於Minas Gerais 及 Rio de Janeiro 洲之四個城市的馬匹及草地，採集得302隻硬蜱，並運用核酸萃取試劑組(Qiagen DNeasy kit)自每隻蜱樣本萃取核酸樣本，隨後以聚合酶連鎖反應試驗(PCR test)分別針對CO1/16S 及GroEL標的基因，以鑑定硬蜱種株及確認立克次體感染。
研究結果：自採集得之硬蜱鑑定出Amblyomma sculptum, Amblyomma cajennense and Dermacentor nitens等三種蜱種，並自4隻硬蜱體中檢測到立克次體感染，其總感染率為1.32%。另外亦檢測到Legionella spp., Klebsiella pneumonia and Rahnella variigena spp.等其他細菌，其總感染率為0.99%。
結論：本研究運用分子檢測技術以確認立克次體存在於巴西硬蜱(Amblyomma sculptum and Dermacentor nitens)體中，研究何種硬蜱可成為立克次體傳播病媒是介入阻斷疾病週期之必要條件，本研究結果顯示馬匹(horses)有可能在巴西東南部成為維續立克次體傳播週期之一環。

關鍵字

蜱媒病原體 ； 巴西 ； 硬蜱 ； 分子鑑定

並列摘要

Background. Spotted Fever, which is caused by Rickettsia spp., was firstly described in Brazil in 1929. Due to the high mortality rate associated with Spotted Fever in Brazil, it is important to understand which vector tick carry this pathogen. This extensive country has great biodiversity of fauna and flora, consequently, ticks are also diverse in species and in the pathogens they carry. The importance and scope of the Rickettsia species has increased in the last 25 years when members of the genus, previously known to be non-pathogenic have been proven otherwise in recent researches, disclosing the complexity of the disease and its emergence and reemergence. For this reason, it is essential to conduct research based on molecular tools for identifying the tick species and for detecting the pathogens carried by ticks.

Aim. The aim of this research is to identify the hard tick species collected from horses and vegetation from Southeastern region of Brazil and also to detect Rickettsia spp. in these ticks.

Methods. A total of 302 ticks were removed from horses and bush vegetation from four different cities (Belo Horizonte, Itamarandiba, Sabara and Guapimirim) of two states (Minas Gerais and Rio de Janeiro) located on the Southeastern region of Brazil. DNA samples were individually extracted from hard ticks using Qiagen DNeasy kit. PCR test was performed targeting CO1 and 16S genes for ticks, as well as GroEL gene for Rickettsia.

Results. From the ticks collected, three tick species were identified as Amblyomma cajennense, Amblyomma sculptum and Dermacentor nitens. Overall, Rickettsia infection was detected in four ticks with an infection rate of 1.32%. In addition, three other bacterial pathogens were also detected in these ticks with a combined total infection rate of 0.99%, and the bacterial pathogens were identified as Legionella spp., Klebsiella pneumonia and Rahnella variigena spp.

Conclusion. Molecular methods demonstrated the evidence of Rickettsia spp. in Amblyomma sculptum and Dermacentor nitens ticks collected from horses from Southeastern region of Brazil. The study of tick species as a vector of Rickettsia is essential for intervening in the disease cycle. These results reveal that horses may contribute to a part of maintaining the transmission cycle of Rickettsia spp. in Southeastern Brazil.

並列關鍵字

Tick-Borne Disease ； Brazil ； Pathogens ； Tick ； Molecular Identification

參考文獻

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