猫立克次氏体病自然疫源地调查及蚊子传播该病的研究

Infection caused by Rickettsia felis is an important tick-borne disease with natural foci, mainly transmitted through vertebrates (mouse and cat) and arthropods (fleas, ticks, mosquitoes). Since its first report in 1990, the disease has been documented in more than 20 countries, and is recognized as an emergent global threat to human health. This disease has not been reported in China. Our prelimianry studies confirmed for the first time the presence of Rickettsia felis in China, and the agents were identified from human beings,dogs,and mice in Jiangsu, Yunnan, Guangdong and Shanghai. In addition, investigation in Yangzhou of Jiangsu province demonstrated that 15.56% (28 /180) of healthy people were sero-positive to Rickettsia felis, and 5.83% (54 / 926) of the examined mosquitoes carried DNA of Rickettsia felis. We propose here to investigate the prevalences of Rickettsia felis in arthropods (ticks, mosquitoes ), mice, companion animals (cats, dogs ) and human beings under different ecological and geographical environments in China. Furhermore, the identified Rickettsia felis strains in this investigation will be genotyped for MLST and phylogenetic analysis. Finally, we attept to analyze the dynamic levels of rickettsial DNA and RNA in mosquitoes (adult, larva and pupa) so that it can be determined whether Rickettsia felis can replicate in mosquitoes, and the mosquito can transmit Rickettsia felis in a vetical fashion. This study will provide key information, theoretical and technical support for the prevention and control of Rickettsia felis.

猫立克次氏体病是一种以脊椎动物和节肢动物为储存宿主和传播媒介的重要自然疫源性疾病。自1990年发现以来，该病已在20多个国家报道，被公认为世界范围内对人类健康有重大威胁的疾病。 本项目预试验首次证实猫立克次氏体在我国的存在，从江苏、云南、广东和上海等地的人、犬、小鼠、蜱、蚊子中检测到该病原体。江苏某地5.84%的蚊子（25/428）携带该病原体，而该地15.56%的健康体检者（28/180）显示此病抗体阳性。 我们计划首先调查我国不同生态和地理环境中，猫立克次氏体在节肢动物（蜱、蚊子）、小鼠、伴侣动物（猫、犬）和人中的携带率，并对其进行基因分型和遗传进化分析。通过检测成年蚊子体内猫立克次氏体的DNA/mRNA动态水平，确定该病原体能否在蚊子体内复制；通过检测蚊幼和蛹孵化出的蚊子体内猫立克次氏体的含量，确定蚊子可否垂直传播该病。此研究将为猫立克次氏体的防控提供重要的信息、理论和技术支持。

猫立克次氏体病是一种以脊椎动物和节肢动物为储存宿主和传播媒介的重要自然疫源性疾病。自1990年发现以来，该病已在20多个国家报道，被公认为世界范围内对人类健康有重大威胁的疾病。1）本研究在江苏省扬州市捕获450只雄性的蚊子和345只雌性蚊子，PCR检测表明30%的雄性蚊子和9%的雌性蚊子携带立克次氏体。MLST分析表明检测的立克次氏体属于和在非洲发现的立克次氏体新种（JN620082/JQ354961）高度相似。2）PCR检测立克次氏体核酸的阳性率较低，分别为0.1%（人，1/822）， 0.8%（犬，8/1059），10%（鼠，1/10），10%（蜱虫 Rhipicephalus sanguineus，15/46），16%（虱子Linognathus setosus，6/37）和6%（蚊子，25/428）。血清学检测表明，抗立克次氏体的抗体阳性率分别为16%（人，28/180），47%（犬，128/271）和21%（猫，19/90）。3）本研究从我国的25个省份采集3051只蚊子，并进行蚊子的种的鉴定以及立克次氏体的分子检测。本研究共发现5个蚊子的种，分别是Aedes albopictus, Anopheles sinensis, Armigeres subalbatus, Culex pipiens pallens and Culex tritaeniorhynchus。其中雄性蚊子 40.7%，雌性蚊子为59.3%(1809/3051). Plasmodium (P. relictum)的阳性率较低（0.3%， 10/3051），在三个蚊子的种发现（Cx. pipiens pallens 8/1620, 0.5%; An. sinensis 1/168, 0.6%; Ar. subalbatus 1/377, 0.3%）。本项目在我国的21个省发现二个立克次氏体的种（R. bellii, 70/3051, 2.3%; R. felis, 49/3051, 1.6%）。本研究表明，中国的蚊子普遍携带猫立克次氏体和R. belli. 本研究系统对我国蚊子携带立克次氏体进行了系统的流行病学调查以及其传播途径的研究，为该病原体的防控提供了重要的理论支撑。