Investigation Of Tick-borne Pathogens Carried By Ticks In Five Cities Of Liaoning Province

Background: Because of the need to suck blood and change hosts at each stage of growth and the variety of hosts,ticks can carry a variety of pathogens,just fewer than mosquitoes.At least 15 tick-borne pathogens have been identified in China,including emerging tick-borne infectious diseases such as fever with thrombocytopenia syndrome,Q fever,babesiosis and spotted fever.Most of the previous studies are single-species tick-borne pathogens in a single area,and there are at most two or three kinds of tick-borne pathogens,which are lack of screening for a variety of tick-borne pathogens in a certain range.Objective: The screening of tick-borne pathogens was carried out in Liaoning Province,and the species and distribution of tick-borne pathogens in Liaoning Province were analyzed,as well as the areas with high and low incidence of tick-borne diseases,so as to provide pathogen basis for the prevention,control and detection of tick-borne diseases in this area.to improve the understanding and diagnosis rate of tick-borne diseases among medical staff.Through sequencing analysis,the subspecies of rickettsia-carrying ticks in Liaoning Province were refined,providing data support for further in-depth research and improving the prevention and control of tick-borne infectious diseases.Methods:(1)subjects: ticks in Anshan City,Liaoyang City,Dandong City and Huludao City in 2022;ticks in Anshan City and Liaoyang City in 2021;ticks in Dalian City in2018(2)tick samples were collected by artificial flag method and livestock body surface extraction method.Statistics of collection area,time and number,morphological identification of ticks.(3)to establish a nested PCR method for detection of Rickettsia,Severe fever thrombocytopenia syndrome virus(SFTSV),Coxiella burnetii,Babesia,Ehrlichia chaffeensis,Anaplasma,Borrelia burgdorferi of Lyme disease,Orientia tsutsugamushi and Francissella tularensis.(4)the positive samples were sequenced to determine the gene sequence of the virus,and the genetic evolution was further analyzed.Results: Six tick-borne pathogens were detected in the five cities of Liaoning Province,which were Rickettsia,Babesia,SFTSV,Coxiella burnetii,Anaplasma and Ehrlichia chaffeensis,while none were detected in Borrelia burgdorferi of Lyme disease,Orientia tsutsugamushi and Francissella tularensis.Among them,the largest number of tick-borne pathogens were detected in Rickettsia,accounting for 42.93% of the total tick-borne pathogens;Babesia accounted for 25.00%;SFTSV accounted for 6.06%,mainly distributed in Dalian and Liaoyang City;Coxiella burnetii accounted for 5.81%,mainly distributed in Anshan City;Anaplasma accounted for 18.94%;Ehrlichia chaffeensis accounted for 1.26%,mainly distributed in Liaoyang City.(1)The positive rate of Rickettsia gltA was 49.32%,that of Babesia was 28.77%,that of Rickettsia 17 kda was65.75%,that of SFTSV was 16.44%,that of Anaplasma was 42.47%,that of Ehrlichia chaffeensis was 5.48%,and the other pathogens were not detected in Liaoyang City.(2)The positive rate of Rickettsia gltA was 51.90%,that of Babesia was 45.57%,that of Rickettsia 17 kda was 63.29%,that of Coxiella burnetii was 25.32%,that of SFTSV was5.06%,that of Anaplasma was 30.38%,and that of other pathogens were not detected in Anshan City.(3)The positive rate of Rickettsia 17 kda was 3.23%,that of Coxiella burnetii was 1.61%,and other pathogens were not detected in Huludao City.(4)The positive rates of Rickettsia gltA were 38.10%,that of Babesia was 32.14%,that of Rickettsia 17 kda was 64.29%,that of Coxiella burnetii was 2.38%,that of SFTSV was1.19%,that of Anaplasma was 14.29% and that of Ehrlichia chaffeensis was 1.19% in Dandong City.(5)The positive rate of Rickettsia gltA was 57.14%,that of Babesia was53.57%,that of Rickettsia 17 kda was 50.00%,that of SFTSV was 25.00%,that of Anaplasma was 28.57%,and other pathogens were not detected in Dalian City.(6)In2021,Rickettsia and SFTSV co-infection and Rickettsia and Babesia co-infection were detected in a single tick in Liaoyang City.Rickettsia,Babesia,Anaplasma and SFTSV were detected in different years in Liaoyang City,and Rickettsia,Anaplasma and Q-Bernarcoxium were detected in different years in Anshan City,which proved the consistency in time.(7)Sequencing analysis showed that there were three kinds of Rickettsia carried by ticks in Liaoning Province.Candidatus Rickettsia jingxinensis were common in Liaoning Province,and Rickettsia raoultii was distributed in Liaoyang City,Anshan City and Dandong City,while a small number of Rickettsia felis carried by ticks were found in Dalian City and Dandong City.Conclusions: Tick-borne pathogens such as Rickettsia,Babesia,Q fever,SFTSV,Anaplasma and Ehrlichia chaffeensis were detected in Liaoning Province.Among them,babesia and Ehrlichia chaffeensis were detected for the first time in Liaoning Province in the past 15 years,suggesting the possibility of infection with babesiosis and human monocytic ehrlichiosis.The number and species of tick-borne pathogens carried by ticks in southern Liaoning and eastern Liaoning were more than those in other areas of Liaoning.Liaoning province exist three kinds of rickettsia carried by ticks,namely,Rickettsia felis,Rickettsia raoultii and Candidatus Rickettsia jingxinensis.