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

Background:Human babesiosis is an emerging zoonotic disease transmitted by ticks in China. A few systematic reports onBabesiaspp. was involved with ticks, especially in the human babesiosis endemic areas in Northeastern China. Materials and Methods:Ticks were collected from 30 individual waypoints along 2.0 km transects in two recreational forests.Babesiaspp. infection in ticks was screened by amplifying the partial 18s rRNA gene with subsequent sequencing. Multivariate logistic regression analysis was used to determine the association between tick infection and related environmental risk factors. Cluster analyses were performed using SaTScan v6.0 software to identify any geographical cluster of infected ticks. Results:A total of 2380Ixodes persulcatusand 461Haemaphysalis concinnaticks were collected. Of the 0.97% ofI. persulcatusticks that tested positive, fiveBabesiaspecies were identified, includingB. 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. concinnaticks tested positive forB. bigemina(n = 1),B. divergens(n = 1), three genetic variants ofBabesiarepresented by HLJ-874, which was closely related toBabesiasp.MA#361-1, and eight otherBabesiavariants represented by HLJ242, which were similar toB. crassa. Each study site had 5-6 differentBabesiaspp. One waypoint was more likely to yieldB. venatorum(relative risk = 15.36,p = 0.045) than all other waypoints. Conclusions:There exists a high genetic diversity ofBabesiaspp. across a relatively small sampled region. Further study is needed to understand the risks these variants pose to human health.