We surveyed tick species and their carried pathogens for three important emerging zoonotic diseases(Babesiosis,Lyme disease,and fever with thrombocytopenia syndrome)at border areas between China and Mongolia,to provide data support for the construction of a database on cross-border transmission of important tick-borne diseases and the prevention and control of zoonotic tick-borne diseases in border areas.In 2023-2024,tick samples were collected from 12 border areas along the Sino-Mongolian bor-der,and tick species were identified according to morphology and molecular biology,then tested for the pathogens of three newly emerging zoonotic diseases with real-time fluorescence quantitative PCR and conventional PCR.Positive samples were verified through gene sequencing.A total of 2 477 ticks of five genera and nine species were collected from the border areas of China and Mongolia.The dominant tick species were identified as the grassland leatherback tick,the full-groove tick,and the small glaucous-eyed tick.The overall positivity rates of ticks carrying Babesia,Lyme disease spirochetes,and fever with thrombocytopenia virus in the 12 border ar-eas were 8.32%,11.59%,and 0%,respectively.Babesia,the most widely distributed tick species,was detected in ticks at eight areas in the eastern,central,and western parts of the China-Mongolia border.This species was found in eastern,central,and western ports along the Sino-Mongolian border;showed tick positivity rates of 0.37%-38.82%;and was most frequently carried by full-groove hard ticks.Spirochetes of Lyme disease were the next most widely distributed,and were detected in samples from four port areas,primarily in the eastern ports along the Sino-Mongolian border;97.2%of positive samples were detected in full-groove hard ticks.Zoonotic Babe-sia spp.were widely distributed in the border crossing areas of China and Mongolia,and included five species of Babesia microti,Ba-besia venatorum,and Babesia divergens,whereas the Lyme disease spirochetes were prevalent mainly in the east,including five geno-types of Borreliella garinii,Borreliella afzelii,and Borrelia burgdorferi sensu stricto.Co-infection with Babesia and Lyme disease spiro-chetes was present in hard ticks throughout the groove,and co-infected samples accounted for 74.27%of Babesia positive and 53.31%of Lyme disease positive samples.Thus,Babesia and Lyme disease spirochetes were found to be important tick-borne emerging zoo-notic pathogens in the Sino-Mongolian border crossing areas,the infected ticks were primarily full-grooved hard ticks,and co-infections were found.

We surveyed tick species and their carried pathogens for three important emerging zoonotic diseases(Babesiosis,Lyme disease,and fever with thrombocytopenia syndrome)at border areas between China and Mongolia,to provide data support for the construction of a database on cross-border transmission of important tick-borne diseases and the prevention and control of zoonotic tick-borne diseases in border areas.In 2023-2024,tick samples were collected from 12 border areas along the Sino-Mongolian bor-der,and tick species were identified according to morphology and molecular biology,then tested for the pathogens of three newly emerging zoonotic diseases with real-time fluorescence quantitative PCR and conventional PCR.Positive samples were verified through gene sequencing.A total of 2 477 ticks of five genera and nine species were collected from the border areas of China and Mongolia.The dominant tick species were identified as the grassland leatherback tick,the full-groove tick,and the small glaucous-eyed tick.The overall positivity rates of ticks carrying Babesia,Lyme disease spirochetes,and fever with thrombocytopenia virus in the 12 border ar-eas were 8.32%,11.59%,and 0%,respectively.Babesia,the most widely distributed tick species,was detected in ticks at eight areas in the eastern,central,and western parts of the China-Mongolia border.This species was found in eastern,central,and western ports along the Sino-Mongolian border;showed tick positivity rates of 0.37%-38.82%;and was most frequently carried by full-groove hard ticks.Spirochetes of Lyme disease were the next most widely distributed,and were detected in samples from four port areas,primarily in the eastern ports along the Sino-Mongolian border;97.2%of positive samples were detected in full-groove hard ticks.Zoonotic Babe-sia spp.were widely distributed in the border crossing areas of China and Mongolia,and included five species of Babesia microti,Ba-besia venatorum,and Babesia divergens,whereas the Lyme disease spirochetes were prevalent mainly in the east,including five geno-types of Borreliella garinii,Borreliella afzelii,and Borrelia burgdorferi sensu stricto.Co-infection with Babesia and Lyme disease spiro-chetes was present in hard ticks throughout the groove,and co-infected samples accounted for 74.27%of Babesia positive and 53.31%of Lyme disease positive samples.Thus,Babesia and Lyme disease spirochetes were found to be important tick-borne emerging zoo-notic pathogens in the Sino-Mongolian border crossing areas,the infected ticks were primarily full-grooved hard ticks,and co-infections were found.