Co-infection of tick-borne bacterial pathogens in ticks in Inner Mongolia, China

Abstract

Tick-borne infectious diseases pose a serious health threat in certain regions of the world. Emerging infectious diseases caused by novel tick-borne pathogens have been reported that are causing particular concern. Several tick-borne diseases often coexist in the same foci, and a single vector tick can transmit two or more pathogens at the same time, which greatly increases the probability of co-infection in host animals and humans and can lead to an epidemic of tick-borne disease. The lack of epidemiological data and information on the specific clinical symptoms related to co-infection with tick-borne pathogens means that it is not currently possible to accurately and rapidly distinguish between a single pathogen infection and co-infection with multiple pathogens, which can have serious consequences. Inner Mongolia in the north of China is endemic for tick-borne infectious diseases, especially in the eastern forest region. Previous studies have found that more than 10% of co-infections were in host-seeking ticks. However, the lack of data on the specific types of co-infection with pathogens makes clinical treatment difficult. In our study, we present data on the co-infection types and the differences in co-infection among different ecological regions through genetic analysis of tick samples collected throughout Inner Mongolia. Our findings may aid clinicians in the diagnosis of concomitant tick-borne infectious diseases.

Fig 1. Sampling areas.

Geographical areas used for sampling were located in the north of China, and were divided mainly on the basis of different ecological and environmental characteristics. Sampling area 1 was a mainly forested habitat, sampling area 2 was a grassland habitat, and sampling area 3 was the semi-desertification steppe / Gobi Desert. The tick sampling collection period was from May 2015 until June 2019. ①—Sampling area 1 covering two leagues: Hulunbuir and Hinggan. ②—Sampling area 2 including Hohhot, Ulanqab and Xilin Gol, Tongliao and Chifeng. ③—Sampling area 3 including Baotou, Wuhai, Ordos, Bayan Nur, and Alxa. Map source: National Earth System Science Data Center (http://www.geodata.cn/data/datadetails.html?dataguid=223718677040067&docid=4590).