Abstract:

[Objective] The aim of this study was to understand the prevalence of Anaplasma infection in ticks and sheep in Aksu Prefecture of Xinjiang Uygur Autonomous Region. [Method] A total of 192 ticks and 477 sheep anticoagulant blood samples were collected. After morphological identification, the ticks were molecularly confirmed by using PCR assays targeting mitochondrial 16S rDNA and ITS-2 genes. The presence of Anaplasma ovis （A. ovis） and Ananlasma phagocytophilum （A. phagocytophilum） in the ticks and sheep anticoagulant blood samples were detected by using conventional PCR assay and nested PCR assay with specific primers, respectively. Statistical analysis were performed to assess the the differences in prevalence of A. ovis and A. phagocytophilum among ticks of different genders as well as sheep reared in various regions and feeding modes. [Result] The 192 ticks, including 79 male ticks and 113 female ticks, belonged to 2 genera and 3 species. The number of ticks identified as Rhipicephalus turanicus （R. turanicus）, Hyalomma asiaticm （H. asiaticm） and Hyalomma anatolicum （H. anatolicum） accounted for 52.60%, 45.83% and 1.56% of the total, respectively. In the tick samples, the overall positive rate of Anaplasma infection was 7.29%, while the mixed infection of A. ovis and A. phagocytophilum was not observed; the positive rates of Anaplasma infection for R. turanicus, H. asiaticm, and H. anatolicm were 8.91%, 5.68%, and 0, respectively, with statistically significant differences （χ²=3.20, P<0.05）; the positive rates of Anaplasma infection for male and female ticks were 6.33% and 7.96%, respectively, with no statistically significant difference （χ²=0.30, P>0.05）. In the sheep anticoagulant blood samples, the overall positive rate of Anaplasma infection was 51.15%, which had statistically significant difference with that of the tick samples （χ²=111.35, P<0.05）; the mixed infection rate of A. ovis and A. phagocytophilum was 16.56%; the positive rates of Anaplasma infection in captive and free range sheep were 28.16% and 83.00%, respectively, with statistically significant difference （χ²=139.81, P<0.05）; Kuqa City and Xayar County had the lowest positive rate of Anaplasma infection at 5.00%, and Wensu County had the highest positive rate at 64.83%, with statistically significant difference （χ²=27.72, P<0.05）. [Conclusion] The prevalence of Anaplasma infection in ticks and sheep in Aksu Prefecture was common, and the prevention and control of anaplasmosis should be strengthened.

Key words: tick, species identification, Anaplasma ovis, Ananlasma phagocytophilum, molecular epidemiological investigation