中国山西农村猪圈作为成人流行性乙型脑炎病毒流行的潜在危险因素。
Pigsties near dwellings as a potential risk factor for the prevalence of Japanese encephalitis virus in adult in Shanxi, China.
作者信息
Ren Xiaojie, Fu Shihong, Dai Peifang, Wang Huanyu, Li Yuanyuan, Li Xiaolong, Lei Wenwen, Gao Xiaoyan, He Ying, Lv Zhi, Cheng Jingxia, Wang Guiqin, Liang Guodong
机构信息
Department of Immunology and Microbiology, Shanxi Medical University, Taiyuan, 030001, China.
State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China.
出版信息
Infect Dis Poverty. 2017 Jun 8;6(1):100. doi: 10.1186/s40249-017-0312-4.
BACKGROUND
The increasing trend of adult cases of Japanese encephalitis (JE) in China, particularly in northern China, has become an important public health issue. We conducted an epidemiological investigation in the south of Shanxi Province to examine the relationships between mosquitoes, Japanese encephalitis virus (JEV), and adult JE cases.
METHODS
Mosquito specimens were collected from the courtyards of farmers' households and pig farms in Shanxi Province. Mosquitoes were pooled, homogenized, and centrifuged. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect mosquito-borne arbovirus genes in homogenates. Specimens positive for these genes were inoculated into the baby hamster kidney cell line (BHK-21) to isolate virus. Minimum infection rate was calculated and phylogenetic analyses were performed.
RESULTS
A total of 7 943 mosquitoes belonging to six species in four genera were collected; Culex tritaeniorhynchus accounted for 73.08% (5 805/7 943), C. pipiens pallens for 24.75% (1 966/7 943), and the remaining 3% (104/ 7943) consisted of Anopheles sinensis, Aedes vexans, Ae. dorsalis, and Armigeres subalbatus. Sixteen pools were positive for JEV based on RT-PCR using JEV pre-membrane gene nested primers. Phylogenetic analyses showed that all JEVs belonged to genotype I; two pools were positive using Getah Virus (GETV) gene primers. In addition, one JEV strain (SXYC1523) was isolated from C. pipiens pallens specimens. These results indicate that the minimum infection rate of JEV in mosquito specimens collected from the courtyards of farmers' households with pigsties was 7.39/1 000; the rate for pig farms was 2.68/1 000; and the rate for farmers' courtyards without pigsties was zero.
CONCLUSIONS
The high-prevalence regions of adult JE investigated in this study are still the natural epidemic focus of JEV. Having pigsties near dwellings is a potential risk factor contributing to the prevalence of adult JE. To prevent the occurrence of local adult JE cases, a recommendation was raised that, besides continuing to implement the Expanded Program on Immunization for children, the government should urge local farmers to cease raising pigs in their own courtyards to reduce the probability of infection with JEV.
背景
中国成人乙型脑炎（乙脑）病例呈上升趋势，尤其在华北地区，这已成为一个重要的公共卫生问题。我们在山西省南部进行了一项流行病学调查，以研究蚊子、乙脑病毒（JEV）与成人乙脑病例之间的关系。
方法
从山西省农户庭院和养猪场采集蚊子标本。将蚊子合并、匀浆并离心。采用逆转录聚合酶链反应（RT-PCR）检测匀浆中蚊媒虫媒病毒基因。将这些基因阳性的标本接种到幼仓鼠肾细胞系（BHK-21）中分离病毒。计算最低感染率并进行系统发育分析。
结果
共采集到4属6种7943只蚊子；三带喙库蚊占73.08%（5805/7943），淡色库蚊占24.75%（1966/7943），其余3%（104/7943）包括中华按蚊、骚扰阿蚊、背点伊蚊和白纹伊蚊。使用JEV前膜基因巢式引物进行RT-PCR检测，16个混合样本JEV呈阳性。系统发育分析表明，所有JEV均属于基因型I；使用盖塔病毒（GETV）基因引物检测，2个混合样本呈阳性。此外，从淡色库蚊标本中分离出1株JEV毒株（SXYC1523）。这些结果表明，从有猪圈的农户庭院采集的蚊子标本中JEV的最低感染率为7.39/1000；养猪场为2.68/1000；无猪圈的农户庭院感染率为零。
结论
本研究调查的成人乙脑高流行区仍是JEV的自然疫源地。住宅附近有猪圈是导致成人乙脑流行的潜在危险因素。为预防当地成人乙脑病例的发生，建议除继续实施儿童扩大免疫规划外，政府应督促当地农户停止在自家庭院养猪，以降低感染JEV的概率。
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