Genetic Diversity and Coexistence of Babesia in Ticks (Acari: Ixodidae) from Northeastern

Background Babesiosis is an emerging zoonosis in humans with significant and increasing health burden in China. A few systematic reports on Babesia spp. was involved with ticks, especially in the human babesiosis endemic areas. Methods The ticks were collected from 30 individual waypoints along 2.0 km transects in two recreational forested areas in Northeastern China. Then we screened them for Babesia spp. infection by amplifying the partial 18s rRNA gene with subsequent sequencing. Multivariate logistic regression analysis was used to access the association between infections and some related risk factors. The cluster analyses were performed using SaTScan v6.0 Software for identifying the geographic cluster of the positive samples in ticks from each waypoint. Results A total of Ixodes persulcatus (n=2380) and Haemaphysalis concinna (n=461) ticks were collected. The 0.97% of I. persulcatus ticks were infected with five Babesia species, including B. bigemina (n=6), B. divergens (n=2), B. microti (n=3), B. venatorum (n=11) and one novel strain HLJ-8. Thirteen (2.92%) H.concinna ticks contained B. bigemina (n=1), B. divergens (n=1), three genetic variants of Babesia represented by HLJ-874 which was closely related to Babesia sp.MA#361-1, and eight other Babesia variants represented by HLJ242 which were similar to B.crassa. Each study site had 5~6 different Babesia spp. One waypoint was more likely to yield B.venatorum (relative risk=15.36, P=0.045) than all other waypoints. Conclusions There exists a high genetic diversity of Babesia spp. across a relatively small sampled region. Further study is needed to understand the risks these variants pose for human health.