Epidemiological Investigation And Analysis Of Tick Borne Encephalitis Virus(TBEV) In Northeast China

Tick borne encephalitis(TBE),also known as forest encephalitis,is a natural infectious disease caused by tick borne encephalitis virus(TBEV),which mainly attacks the central nervous system of the host.The main clinical manifestations are high fever,headache,paralysis of limbs,etc.In severe cases,it can lead to death of the host.Ticks are the main transmissi on host and storage host of TBEV,which can be transmitted to humans through bites and other means,thus making TBEV continue to prevail in the population and seriously threatening the public health safety of human beings.TBE is reported worldwide and is a global pandemic.In China,TBE is mainly prevalent in northeast and northwest forest areas,and has been reported in Xinjiang,Heilongjiang and Inner Mongolia.In recent years,due to the expansion of human activities and the change of climatic conditions,the epidemic areas and threatened areas of TBE in China have been expanding year by year,and new epidemic characteristics have emerged.In order to understand the prevalence of the virus in the traditional TBEV epidemic area--northeast China,this study carried out an epidemiological study on ticks collected from Jilin city,Jilin province,Hulunbuir City,Inner Mongolia autonomous region,Yichun city,heilongjiang province and the greater Khingan mountains.According to the statistics,a total of 2034 ticks were collected,including 4 tick species.Among them,including 37.1%(755 ticks)of Ixodes persulcatus,29.1%(591 ticks)of Haemaphysalis longicornis,17.7%(361 ticks)of Haemaphysalis prairie,and 16.1%(327 ticks)of Haemaphysalis concinna.The positive rates of ticks carrying TBEV were 10.4% in Jilin city of Jilin province,7.2% in Hulunbuir city of Inner Mongolia autonomous region,11.1% in Daxing'an mountains and 0% in Yichun city of Heilongjiang province.In order to further understand the TBEV epidemic subtype carried by ticks in northeast China,and to lay a foundation for virus pathogenesis and vaccine research.In this study,we obtained three ticks with Genbank Numbers of MN615726,MN615727 and MN615728,respectively.After homology comparison and genetic evolution analysis,we found that all three ticks were Far East subtypes.Epidemiological study on TBEV in tick bites.The blood samples of 886 tick biting patients in Inner Mongolia forestry general hospital from 2017 to 2019 were detected by TBEV RT-q PCR.In 2017,2018 and 2019,the positive rates were 8.05%,7.74% and 7.89%,respectively,with an average positive rate of 7.90%.The amplification and phylogenetic analysis of the positive samples of TBEV envelope E protein showed that the TBEV strains of infected clinical patients with tick bite were all Far East subtypes,which showed high homology with the tick-derived TBEV in this study and were on the same evolutionary branch.In this study,we investigated the prevalence of TBEV in ticks carrying and tick biting patients in Northeast China,and found that the most prevalent type of TBEV is still the Far East subtype.Meanwhile,descriptive statistical analysis was conducted on the basic information and clinical symptoms of TBEV positive patients,which laid a foundation for the effective prevention and control of TBEV in northeast China.