Identification Of Tick Species And Molecular Detection Of Bartonella,Anaplasma And Spotted Fever Group Rickettsia In Ticks From Yak In Shiqu County Of Sichuan Province

Ticks are obligatory?blood-feeding arthropods that parasitize vertebrates?around the world.At present,more than 800 tick species have been identified,which can transmit more than 217 pathogens,including viruses,bacteria and parasites and has a serious impact on human health and animal husbandry.Up to now,there is no reports about tick species and tick-borne diseases in Shiqu county.So,in this research,experimens were conducted to confirm the tick species,infection rates of pathogens in ticks and molecular characterization of these pathogens for providing data on comprehensive control measures on tick-borne diseases.Methods: The ticks collected from Yaks in 8 villages of Shiqu county were classified by morphological and molecular identification of 16 S rRNA and COI genes and phylogenetic analysis were conducted.The partial sequences of gltA and rpoB gene of Bartonella spp,16 S rRNA of Anaplasma spp,ompA and ompB gene of Spotted fever group rickettsia,Yersinia pestis and Tularaemia 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 was analyzed.Results:1)Tick species:A total of 1352 ticks were collected.The Haemphysalis qinghaiensis and Dermacentor everestianus were identified.The dominant species was H.qinghaiensis(29.13%,394/1352)followed by D.everestianus(70.87%,958/1352).2)The pathogens detected: Totally,Bartonella spp.,Anaplasma spp.and SFGR were detected.The infection rates of Bartonella,Anaplasma,and SFGR in ticks were 25.96%(351/1352),15.60%(211/1352)and 49.48%(669/1352),but Yersinia pestis and Tularaemia are both negative,respectively.For H.qinghaiensis and D.everestianus: 1)the infection rates of Bartonella spp.were 47.46%(187/394)and 17.12%(164/958),respectively;2)the infection rates of Anaplasma spp.were 14.21%(56/394)and 16.18%(155/958)respectively.3)the positive rate of SFGR spp.were respectively 57.36%(226/394)and 46.24%(443/958)respectively.The phylogenetic analysis indicated that,B.melophagi,B.grahamii,A.bovis,A.ovis,A.phagocytophilum,Ehrlichia sp Shiqu1,Candidatus.Rickettsia longicornii and R.raoultii were detected.3)The co-infection: The co-infection rates of Bartonella/SFGR,Bartonella /Anaplasma,SFGR / Anaplasma and SFGR /Anaplasma/Bartonella were 10.72%(145/1352),2.96%(40/1352),1.78%(24/1352)and10.58%(143/1352),respectively.For H.qinghaiensis and D.everestianus,1)the infection rates of Bartonella / SFGR were 14.21%(56/394)and 9.30%(89/958),respectively;2)The infection rates of Bartonella/Anaplasma were 3.81%(15/394)and 2.61%(25/958),respectively;3)The infection rates of SFGR/Anaplasma were 9.64%(38/394)and 10.97%(105/958),respectively;4)The infection rates of Bartonella/ SFGR /Anaplasma were 3.05%(12/394),and 1.25%(12/958).Conclusion: In Shiqu county,there existed H.qinghaiensis and D.everestianus.D.everestianus is the dominant species with a distribution in 7 villages(except Zhenda).H.qinghaiensis is only found in three villages of semi-agricultural and semi-pastoral areas with relatively low altitude.Bartonella,Anaplasma and SFGR were firstly detected in ticks of Shiqu county and there existed co-infection of these pathogens.