Identification Of Tick Species And Molecular Detection Of Spotted Fever Group,bartonella And Anaplasma In Ticks And Blood From Yak In Ruoergai County Of Sichuan Province

Ticks are obligate blood-sucking arthropods that mainly parasitize on the surface of animals.More than 800 species of ticks have been found in the world.At present,it has been determined that ticks can transmit at least 217 species of pathogens,posing a serious threat to human health and the healthy development of animal husbandry.So far,there is no data on the species of ticks and the pathogens infecting yaks and ticks in Ruoergai County.Therefore,this study aims to confirm the species of ticks,the infection rates of pathogens in yaks and ticks,the prevalence and the molecular characteristics,in order to provide comprehensive data on control measures on tick-borne diseases.The ticks collected from Yaks in 4 villages of Ruoergai county were classified by morphological and molecular identification of ITS2 and COI genes and phylogenetic analysis were conducted.The partial sequences of glt A andomp B gene of Spotted fever group rickettsia,glt A and rpo B gene of Bartonella spp,16 S r RNA of Anaplasma spp,16 S r RNA of Borrelia burgdorferi were amplified by PCR,respectively.The positive products were sequenced and sequence obtained were compared through the NCBI database.Finally,the infection rates of pathogens were analyzed.A total of 632 ticks were collected.The Rhipicephalus microplus and Dermacentor silvarum were identified.The dominant species was R.microplus(75.8%,479/632)followed by D.silvarum(24.2%,153/632).Totally,SFGR and Bartonella spp.were detected.The infection rates of SFGR and Bartonella in ticks were 23.4%(148/632)and 3.0%(19/632),but Anaplasma and Borrelia burgdorferi are both negative,respectively.For R.microplus and D.silvarumthe infection rates of SFGR spp.were 11.1%(53/479)and 62.1%(95/153),the positive rates of Bartonella spp.were 2.3%(11/479)and 2.2%(8/153).A total of 104 yaks samples were collected,the infection rates of SFGR spp.and Anaplasma spp.were13.5%(14/104).But Bartonella and Borrelia burgdorferi are both negative,respectively.The phylogenetic analysis indicated that,R.raoultiiin ticks were detected,R.raoultii,Rickettsia felis and Anplasma capra in yak samples were detected.The co-infection rates of SFGR/Bartonella were 2.2%(14/632)in ticks.For R.microplus and D.silvarum,the infection rates of SFGR/Bartonella were 2.5%(12/479)and 1.3%(2/153),The infection rates of SFGR/Anaplasma were 5.8%(6/104)in yak samples.In Ruoergai County,there existed R.microplus and D.silvarum.R.microplusis is the dominant species with distribution in 4 villages.SFGR and Bartonella were firstly detected in ticks with SFGR and Anaplasma in yak samples of Ruoergai County and there existed co-infection of these pathogens.