Research On Main Ticks Morphology And Ticks Borne Disease In Qinghai Province, China

Ticks(Acari: Ixodid a) are parasitic acari that suck blood from the vertebrate hosts. They can transmit a number of pathogenic organisms to humans and domestic animals and cause a variety of important natural focal diseases and zoonoses. To date, more than 900 species of ticks have been recorded globally, with two major families, namely Ixodidae and Argasidae, the former generally referred to as hard ticks and the later also known as soft ticks. In China, about eleven generas of ticks have been recorded which covered approximately 120 species, including 10 species of Argasidae and over 100 species of Ixodidae. Ticks species were specific in different zones in China. There were ten major tick-borne diseases reported in China, such as Tick-borne encephalitis(Forest encephalitis, TBE), Q-fever, Oriental spotted fever, North-Asia tick borne spotted fever, Crimean-Congo hemorrhagic fever(Xinjiang hemorrhagic fever), Colorado fever, Tick-borne relapsing fever, Lyme borreliosis, tularemia and piroplasmosis. These diseases were mostly reported in northern and northeastern China in areas,such as Xinjiang, Inner Mongolia, Heilongjiang, Jilin, Liaoning and Yunnan provinces, and few reports on Qinghai province. So investigations on ticks species and epidemiology of tick borne diseases in Qinghai province was very important for public health.⑴Species identification on major ticks species in Qinghai province were conducted based on morphological characters.The results showed that there were four ticks species, including Haemaphysalis qinghaiensis, Dermacentor silvarum, Dermacentor nuttalli and Hyalomma detritum.At the same time, the Basis capituli,Tooth,Anal ditch,Footpad,Haller’s organ,Porsse area et al utalstructure of four species ticks were also observed by electron microscopic. Each tick show There were significant differences in morphology of four species ticks. The results indicated these character of the utalstructure could be used as a basis for tick species identification.⑵ One set of specific primers, designed according to omp A gene specific for Spotted Fever Group Rickettsia(SFGR), were used to amplify omp A gene from DNA samples extracted from ticks pool in Qinghai Province, and the positive samples were sequenced and genetically analyzed by establishment of phylogenetic tree. Of 454 samples, 14 samples were positive for SFGR, including 9 samples positive for R. sibirica and 5 samples positive for R. heilongjiangii, and the infection rates reached to 3.08%. Phylogenetic analysis based on nucleotide sequence showed that R. sibirica Qinghai strain HUN were related and clustered together with R. sibirica 246 strain(U43807)(99.49%) and R. sibirica BJ-90 strain(AF179365)(99.67%); R. heilongjiangii Qinghai strains GL-1 were related and clustered together with R. heilongjiangii Suifen strain HLJ-054(AF179362)(99.18%) and R. heilongjiangii Hulin strain HL-93(AF179364)(99.51%).⑶ Two sets of specific nest PCR primers, designed according to technical advice of controling and prevention on human granulocytic anaplasmosis, were used to amplify 16 S r RNA gene from DNA samples extracted from ticks pool in Qinghai Province, and the positive samples were sequenced and genetically analyzed by establishment of phylogenetic tree. Of 454 samples, 67 samples were positive for A. phagocytophilum and the carrier rate reached to 14.8%. No significantly difference was observed among different regions and ticks species, and firstly detected A. phagocytophilum infections in Haemaphysalis qinghaiensis. Phylogenetic analysis based on nucleotide sequence showed that A. phagocytophilum Qinghai strain HUN were related and clustered together with A. phagocytophilum Japan strain(AY969010)(98.73%) and A. phagocytophilum China Jilin(GQ412339)(99.75%).⑷ Dynamic amount of ticks and the infection rates of Theileria parasites in different months in Qinghai Province were also analyzed. Hyalomma detritum, Dermacentor nuttalli and Haemaphysalis qinghaiensis were identified in the present study, and the infection rates were 48.2%, 9.1% and 42.9%, respectively, and Hyalomma detritum and Haemaphysalis qinghaiensis predominated in Qinghai province;617 blood samples were detected by PCR with universal primers of piroplasms and Theileria parasites as well as specific primers of Theileria luwenshuni, Theileria uilenbergi and Theileria ovis, and phylogenetic analysis were conducted base on 18 S r RNA of positive samples; PCR results showed the infection rates of Theileria parasites were 64.8%, and the infection rates of Theileria luwenshuni and Theileria uilenbergi were 37.6% and 27.2%, respectively, co-infection of Theileria luwenshuni and Theileria uilenbergi were 19.8%, no Theileria ovis was detected in the present study. No significantly differences were observed between Theileria luwenshuni and Theileria uilenbergi(p>0.05), and single infection rate of Theileria luwenshuni or Theileria uilenbergi were also higher than co-infection(p<0.05). Phylogenetic analysis indicated Theileria luwenshuni and Theileria uilenbergi in the present study were in the same cluster with the northwest areas strains, and separated from Beijing strains or south strains, and the strains in the same cluster were distributed as the same area. In addition, the correlativity was observed between dynamic amount of ticks and infection rate of Theileria parasites in the different months in Qinghai Province.In the present study, Haemaphysalis qinghaiensis, Hyalomma detritum, Dermacentor nuttalli and Dermacentor silvarum were the major species in Qinghai province, and those were also described that the Basis capituli,Tooth,Anal ditch,Footpad,Haller’s organ,Porsse area et al utalstructure of four species ticks. The results on Tick borne diseases showed that the infection rates of SFGR and A. phagocytophilum in ticks, and also indicated phylogenetic of SFGR and A. phagocytophilum; in addition, Epidemiological survey of ovine Theileria parasites infection in Qinghai Province documented infection rates, phylogenetic, and the correlativity between dynamic amount of ticks and infection rate of Theileria parasites in different months. These results indicated us that major ticks species and the epidemiology and phylogenetic of major tick borne diseases in Qinghai province, and provided new information on ticks species and the epidemiology of major tick borne diseases in China, at the same time, also provided the scientific data for the prevention and control of tick borne diseases and public health in Qinghai province.