Epidemiological study ofviral acute respiratory infections in Vietnam

1. 背景：热带和亚热带国家的流感病毒感染仍处于恐慌状态，由于中国历史上曾发生过新型流感病毒，因此与中国接壤的越南的流感监测非常重要。目的：1)研究越南作为热带和亚热带国家流感病毒感染的流行病学及通过建立监测网络早期发现新型流感感染；2)金刚烷胺耐药流感病毒的流行病学研究；3)未知致病性急性呼吸综合征的流行病学研究；4)为越南未来流感疫苗接种计划进行基础研究。结果：与河内、胡志明、芽庄和泰阮市建立全国性的监测网络，并结合实验室人力资源的开发。高致病性H5N1禽流感疫情发生在越南，我们的对应机构为控制这一疫情作出了贡献。急性呼吸道综合征主要由流感病毒、腺病毒、肠病毒和RS病毒引起，流行病学背景尚不清楚。与其他热带和亚热带国家一样，流感感染全年都有两个高峰，即6月至9月和12月至2月。这些观察结果表明，在开始暴发之前的3月至5月期间适合接种疫苗。2005年，在日本、美国和大洋洲发现了高流行率的金刚烷胺耐药H3N2与HA基因双突变（s193f和D225N，进化支N）。单个基因片段的进化分析表明，甲型流感病毒的HA和NA基因是顺序进化的。然而，M基因的进化模式被证明是非线性的，与HA和NA基因没有联系。在A/H3N2病毒中，Hal片段的遗传漂变比在A/H1N1病毒中更常见，特别是在A/H3N2病毒的抗原位点。因此，我们可以得出结论，由于流感病毒全年传播，我们强调在热带和亚热带地区进行监测的重要性，在这些地区可能比温带地区更早发现新毒株的出现。少

1. Background:Influenza virus infections in tropical and subtropical countries remain to be um-fear, and as new type of influenza virus occurred historically in China, influenza surveillance in Vietnam bordering on China was quite important.2. Objective:1) Epidemiological study of influenza virus infections in Vietnam as a tropical and subtropical country and early catch of new type of influenza infection by establishing of surveillance net work, 2) epidemiological study of amantadine resistant influenza viruses, 3) epidemiological study of unknown pathogenic acute respiratory syndrome, 4) basic study for future influenza vaccination program in Vietnam.3. Results:We could establish a nationwide surveillance network tied with Hanoi, Ho Chi Minh, Nha Trang, and Tay Nguyen cities in conjunction with development of laboratory human resources. High pathogenic avian influenzas H5N1 outbreak occurred in Vietnam and our counterpart institutions were contributed to control this outbreak.Acute r … More espiratory syndrome, which epidemiological background remained to be unknown, was caused by mainly influenza viruses, adenoviruses, enteroviruses, and RS virus. Influenza infections occurred throughout year with two peaks, June-September and December-February, as in other tropical and subtropical countries. These observations suggest that the time during March to May, before starting outbreak is suitable it vaccination. High prevalence of amantadine resistant H3N2 with dual mutations of HA genes (S 193F and D225N, Clade N) was found in 2005, as in Japan, USA, and Oceania.Pylogenetic analysis of individual gene segments revealed that the HA and the NA genes of the influenza A viruses evolved in as sequential way. However, the evolutionary pattern of the M gene proved to be nonlinear and was not linked with that of the HA and NA genes. Genetic drift in Hal segments, especially in antigenic sites of A/H3N2 viruses, occurred more frequently in A/H3N2 viruses than it did in A/H1N1 viruses.Thus, we can conclude that as influenza viruses circulate throughout the year, we emphasize the importance of surveillance in tropical and subtropical zones, where the emergence of new strains may be detected earlier than it is in the temperate zones. Less