Identification Of Tick Species And Molecular Detection Of Four Tick-Borne Pathogens From Yak In Yajiang County Of Ganzi Prefecture

Ticks are obligatory blood-sucking arthropods that mainly parasitize around the world,which can transmit a number of pathogenic organisms to humans and domestic animals causing a variety of important zoonoses.To date,more than 900 species of ticks have been recorded globally,including Ixodidae and Argasidae.In China,125 spiecies have been reported,including 111 hard tick and 14 soft tick species.So far,there has been no systematic investigation of the species,distribution of ticks and tick-borne diseases in Yajiang County.Therefore,this study aims to investigate the species of ticks and prevalence of tick-borne pathogens,and to provide preliminary information on integated control measures for tick-borne diseases.Methods: Morphological and molecular identification of ITS-2 gene was performed on yak ticks collected from four areas of Yajiang County,and phylogenetic analysis was performed.Partial sequences of the omp B gene of Rickettsia,16 S r RNA of Anaplasma spp.glt A gene of Bartonella spp.and 16 S r RNA of Borrelia burgdorferi.Individually amplified by PCR.The positive products were sequenced and the obtained sequence were compared by the NCBI database.Finally,the infection rates of pathogens were analyzed.Result:1)Ticks species: 548 ticks were collected,a total of two species were founded,including Rhipicephalus microplus and Dermacentor everestianus with morphological and molecular biological identification.The dominant species was R.microplus 96.5%(19/548),follwoed by D.everestianus 3.5%(19/548).2)The pathogens detected: The infection rates of SFGR and Anaplasma spp.in ticks were 13.0%(71/548)and 37.2%(204/548),of which both Bartonella and Borrelia burgdorferi were negative.For R.microplus and D.everestianus: 1)the infection rates of SFGR were 12.5%(66/529)and 26.3%(5/19),respectively,2)the infection rates of Anaplasma spp.were 36.9%(195/529)and 47.4%(9/19),respectively.The phylogenetic analysis indicated that,R.raoulii,Candidatus R.longicornii,A.marginale,A.ovis were detected.3)The co-infection rates of SFGR/Anaplasma were 11.5%(63/548)with the co-infection rate of 11.2%(59/529)in R.microplus and 10.5%(2/19)in D.everestianus,respectively.Conclusion: In this study,two tick species were found in Yajiang County: R.microplus and D.everestianus.Among them,R.microplus was found in 8 villages,and D.everestianus was only found in Kela;SFGR and Anaplasma spp.were detected in ticks in Yajiang County for the first time,and there was a widespread co-infection of SFGR/Anaplasma.