>>>沪江汶川地震专题

【媒介类传染病】

译者注：传病媒介，医学用语，指在疾病传播过程中，使病原体（细菌、病毒、原虫、蠕虫）与感染对象（多为脊椎动物）发生联系的中介因素。传病媒介多为昆虫（双翅目昆虫、跳蚤等）但也有可能是水生软体动物。（据百度百科）

自然灾害，尤其是类似于龙卷风、飓风和洪水这样的气象灾害，会影响传病媒介孳生地以及传病媒介疾疫的传播。一方面，起初的洪水会冲刷掉现有的蚊虫孳生地，但另外一方面，暴雨或河水满溢造成的死水，也会制造出新的孳生地。

这样的状况会导致（通常是在几周的延迟之后）传病媒介群（例如蚊虫等）的增多，并导致疾疫传播。当然，这也取决于当地的媒介种类和它们所偏爱的栖息地环境。感染者或者易感人群的聚集、受到削弱的公共健康基础设施、以及现有疾病控制系统的中断，都是导致媒介传染病传播的因素（36）。

洪水过后的疟疾传播是广为人知的现象。1991年，哥斯达黎加大西洋地区的地震，导致了蚊虫孳生地的环境变化，随后就是疟疾病例的急剧上升（37）。此外，在秘鲁北部干燥的沿海地区，疟疾流行也和由“厄尔尼诺－南方振荡（译者注：指热带太平洋、印度洋之间大气质量的一种大尺度起伏振荡，是赤道附近东太平洋的一种气压异常现象。）”引起的周期性洪水有关（38)。

登革热的传播也受气候条件影响，包括降雨量和湿度，而且经常展现强烈的季候性。不过，其传播却并不与洪水直接相关。之前洪灾中爆发的案例，或许正好与疾病传播的高危期重合。另外自然灾害中基本供水系统和垃圾处理设施遭到破坏，也带来了更多的传病媒介孳生地（大多数是盛水容器），从而加重疫情。

疾疫的爆发风险也可能受到其它复杂因素的影响，比如人类行为的变化（当在外面过夜时会更多地暴露在蚊虫叮咬之下；人口从非登革热病区转移到登革热区；疾病控制活动的暂停；人口过度密集），再比如影响到蚊虫增殖的环境变动（如山崩滑坡、森林砍伐、建造河坝或水源改道等）。

Vectorborne Diseases
Natural disasters, particularly meteorologic events such as cyclones, hurricanes, and flooding, can affect vector-breeding sites and vectorborne disease transmission. While initial flooding may wash away existing mosquito-breeding sites, standing water caused by heavy rainfall or overflow of rivers can create new breeding sites. This situation can result (with typically some weeks' delay) in an increase of the vector population and potential for disease transmission, depending on the local mosquito vector species and its preferred habitat. The crowding of infected and susceptible hosts, a weakened public health infrastructure, and interruptions of ongoing control programs are all risk factors for vectorborne disease transmission (36).

Malaria outbreaks in the wake of flooding are a well-known phenomenon. An earthquake in Costa Rica's Atlantic Region in 1991 was associated with changes in habitat that were beneficial for breeding and preceded an extreme rise in malaria cases (37). Additionally, periodic flooding linked to El Niño–Southern Oscillation has been associated with malaria epidemics in the dry coastal region of northern Peru (38).

Dengue transmission is influenced by meteorologic conditions, including rainfall and humidity, and often exhibits strong seasonality. However, transmission is not directly associated with flooding. Such events may coincide with periods of high risk for transmission and may be exacerbated by increased availability of the vector's breeding sites (mostly artificial containers) caused by disruption of basic water supply and solid waste disposal services. The risk for outbreaks can be influenced by other complicating factors, such as changes in human behavior (increased exposure to mosquitoes while sleeping outside, movement from dengue-nonendemic to -endemic areas, a pause in disease control activities, overcrowding) or changes in the habitat that promote mosquito breeding (landslide, deforestation, river damming, and rerouting of water).