Epidemiology of tick-borne encephalitis in China, 2007- 2018.

Xiaojing Chen,Xiaopeng Qi,Ying He,Shiwen Wang,Wenjing Liu,Shihong Fu,Guodong Liang,Guang Yang,Wenwen Lei,Huanyu Wang,Qikai Yin,Songtao Xu,Fan Li,Abdallah M Samy

doi:10.1371/journal.pone.0226712

Abstract

Tick-borne encephalitis (TBE) is endemic to Europe and some Asian countries and is prevalent in northeast China. We analyzed the epidemiology of TBE in China from 2007 to 2018. A total of 3,364 TBE cases were reported in mainland China from 2007 to 2018, for an annual incidence of 0.09 to 0.44/100,000. Among the TBE cases, 89.92% were reported in forest areas (41.94% in DaXingAnLing, 8.70% in XiaoXingAnLing, and 39.21% in ChangBaiShan) in northeast China. The TBE cases were primarily male with a proportion of 67.15% (2,259/3,364 cases) and in 40–49-year age group with a proportion of 31.89% (1,073/3,364 cases). The epidemiology of TBE differed slightly among the three forest regions. Domestic workers and forestry workers accounted for the most of the TBE cases in DaXingAnLing, and domestic workers and farmers in XiaoXingAnLing and ChangBaiShan, respectively. The TBE cases mainly occurred from April to August with a peak in June. The TBE laboratory confirmed rate in DaXingAnLing (84.14%, 1,189/1,413 cases) was highest, compared with XiaoXingAnLing and ChangBaiShan (13.99% and 11.37%, respectively). Moreover, the hospital with the highest laboratory confirmed rate (88.01%, 1,336/1,518 cases) was Inner Mongolia Forestry General Hospital of DaXingAnling region. Systematic enhanced TBE surveillance and a vaccination program are needed to improve the laboratory confirmed rate and reduce the incidence of TBE in northeast China.

Highlights

Tick-borne encephalitis (TBE) is transmitted by ticks carrying the tick-borne encephalitis virus (TBEV), which invades the central nervous system and causes serious morbidity
TBE cases were mainly distributed in northeast China at altitude > 500 m, including in DaXingAnLing, XiaoXingAnLing, and ChangBaiShan
10.08% (339 cases) of the TBE cases occurred at altitude of < 500 m (S1 Table and Fig 2)

Summary

Methods

The ethical approval of this study was determined by the Chinese Center for Disease Control and Prevention, that the collection of data from TBE cases was part of continuing public health surveillance of an infectious disease and was exempt from institutional review board assessment. According to the national guidelines, the diagnostic criteria for a clinically- diagnosed TBE case is based on the presence of clinical symptoms (such as acute fever, headache, vomiting, and/or typical central nervous system symptoms) in connection with exposure to forest during spring or summer, or a history of tick bite. TBE is not a notifiable disease, clinical TBE cases diagnosed at medical institutions have been reported to the Chinese Information System for Diseases Control and Prevention (CISDCP) by the majority of provinces since 2002.

Results

Discussion

Conclusion