Molecular surveillance reveals a potential hotspot of tick-borne disease in Hulunbuir City, Inner Mongolia

A molecular surveillance of tick-borne diseases was performed in Hulunbuir City, Inner Mongolia. A total of 149 ticks including three species ( Ixodes persulcatus , Haemaphysalis concinna , and Dermacentor silvarum ) were collected. As many as 11 tick-borne bacterial pathogens were identified in them. Some of them have high positive rates. For example, Candidatus Rickettsia tarasevichiae was detected with a high prevalence of 72.48%, while Candidatus Lariskella sp. was detected in 31.54% of ticks. For both Rickettsia raoultii and Anaplasma phagocytophilum , two distinct genotypes were identified based on their phylogenetic trees based on 16S rRNA, gltA , and groEL sequences. Remarkable genetic diversity was also observed for 16S and flaB genes of Borreliella garinii , an agent of Lyme disease. Rickettsia heilongjiangensis causing Far-Eastern spotted fever (2.68%, 4/149), Ehrlichia muris causing human ehrlichiosis (4.70%, 7/149), Borrelia miyamotoi causing relapsing fever (2.01%, 3/149), and Borreliella afzelii causing Lyme disease (2.01%, 3/149) were also detected. Additionally, a previously uncharacterized Anaplasma species closely related to Anaplasma ovis was identified. Herein we name it “ Candidatus Anaplasma mongolica”. Based on these results, we propose that Hulunbuir City, as well as the northeast part of Inner Mongolia, might be a potential hotspot of tick-borne diseases.