1. Epidemiological features of rabies and molecular evolution characteristics of the rabies virus strains in Xishuangbanna prefecture of Yunnan province, China
Hongmei YANG ; Yun FENG ; Mingyue LAI ; Baohua LI ; Jianhua FAN ; Long MA ; Honghua WEN ; Yunqiao XU ; Yinghua DAO ; Meihui SU ; Huaxing LIU ; Yuzhen ZHANG ; Weihong YANG ; Hailin ZHANG
Chinese Journal of Experimental and Clinical Virology 2019;33(2):113-120
Objective:
To understand the epidemiologic features of the rabies in Xishuang banna prefecture of Yunnan province, China in 2008-2017 and the viral molecular-evolution characteristics.
Methods:
The data of rabies case questionnaire were collected. The brain tissue samples from mad dogs, suspicious sick dogs and human brain tissue, saliva and cerebrospinal fluid samples from rabies patients were collected in Xishuangbanna. Coding region of nucleoprotein and glycoprotein genes were amplified by RT-PCR and sequenced. Homology and phylogenetic analysis were performed using the relevant bioinformatics software.
Results:
A total of 62 cases of human rabies were occurred in 28 districts of the 3 counties, Xishuangbanna prefecture in 2008-2017. Of them, 37 cases in Jinghong county, 15 in Menghai county and 10 in Mengla county. In which 48 cases were bitten by domestic dogs (77.42%), 11 cases were bitten by wild dogs (17.74%). Rabies case was occurred every year in the past decade. The seasonal incidence was not obvious. The majority of patients were aged from 30 to 59 years-old, with the youngest 1 year-old and the eldest 91 year-old. The male to female ratio was 1.70∶1, most cases were farmers. The nucleotide sequences of nucleoprotein gene of 9 virus strains (7 from Jinghong, 1 from Menghai and 1 from Mengla) were obtained from the samples of dogs and patients. Homology and phylogenetic analyses indicated that the 5 strains belonged to clade China-Ⅰ, 3 clade China-Ⅱ and 1 clade China-Ⅵ. The nucleotide sequences of glycoprotein gene of 5 virus strains (3 from Jinghong, 1 from Menghai and 1 from Mengla) were obtained from these positive samples, and all were clade China-Ⅰ, it is same with nucleoprotein genes analysis result from these 5 virus strains. These China-Ⅰ and China-Ⅱ strains from Xishuangbanna have a closer genetic relationship with same clade strains isolated from Pu’er and other prefectures of Yunnan province as well as Sichuan, Guizhou and Guangxi. The China-Ⅵ strain from Xishuangbanna share high homology and genetic relationship with China-Ⅵ strains isolated from southwestern Yunnan and neighbouring countries such as Myanmar, Laos and Vietnam in recent years.
Conclusions
In Xishuangbanna, rabies mainly occurred in rural area and domestic dog was the main source of transmission. These RABV clades China-Ⅰ, China-Ⅱ and China-Ⅵ were found in this region and the China-Ⅰ was principal clade. The transmission source of China-Ⅰ and China-Ⅱ were from adjacent areas in the province and China-Ⅵ was from Myanmar and Laos.