>>>沪江汶川地震专题

【与人群密集相关的疫病】

灾后疏散人口时常会出现人群密集，并助长传播性疫病的扩散。灾后是否出现麻疹等疫病、以及疫病传播的风险，取决于受感染人群中防疫接种率的基本状况，尤其是在15岁以下儿童中的接种率。拥挤的生存环境会助长麻疹等疫病的传染，因而需要更高的接种比例才能避免疫病爆发（32）。1991年菲律宾 Pinatubo火山爆发后，疏散的人群中爆发麻疹，18000人感染。Aceh遭受飓风后，在Aceh Utara地区出现35例小规模麻疹群发，尽管后来持续进行了防疫接种的宣传和推动，还是有个别病例或群发病例出现（26）。在巴基斯坦，2005年南亚地震后也出现了零星和群发的麻疹病例（在地震后6个月内病人超过400名）（25）。

原核生物性脑膜炎通过人与人传播，尤其在拥挤的环境中。亚齐省和巴基斯坦流离失所的人口中都有脑膜炎病例和死亡的病例（25，26）。在上述两地发生疫情时，如及时采取抗菌防疫工作应当可以阻止脑膜炎的传播。最近没有在受灾人口中大规模爆发该疫病的报告，但对由于地区冲突而迁移的人群中该疫病的爆发则有明确的记录（34）。

急性呼吸道感染（ARI）是导致灾民生病或死亡的重要原因，特别是对于5岁以下的儿童。缺乏医疗手段和抗菌药物提高了由于急性呼吸道感染（ARI）造成的死亡率。灾民面临的危险因素包括：人群拥挤、在室内使用明火煮食、和营养不良。在1998年飓风 Mitch 吹袭尼加拉瓜30天后，急性呼吸道感染（ARI）患者增加了4倍（35）；而2004年印尼亚齐省海啸（26）和2005年巴基斯坦地震（25）灾害中，流离失所的灾民中患上急性呼吸道感染（ARI）和由此死亡的病例也是最多的。

Diseases Associated with Crowding
Crowding is common in populations displaced by natural disasters and can facilitate the transmission of communicable diseases. Measles and the risk for transmission after a natural disaster are dependent on baseline immunization coverage among the affected population, and in particular among children <15 years of age. Crowded living conditions facilitate measles transmission and necessitate even higher immunization coverage levels to prevent outbreaks (32). A measles outbreak in the Philippines in 1991 among persons displaced by the eruption of Mt. Pinatubo involved >18,000 cases (33). After the tsunami in Aceh, a cluster of measles involving 35 cases occurred in Aceh Utara district, and continuing sporadic cases and clusters were common despite mass vaccination campaigns (26). In Pakistan, after the 2005 South Asia earthquake, sporadic cases and clusters of measles (>400 clinical cases in the 6 months after the earthquake) also occurred (25).

Neisseria meningitidis meningitis is transmitted from person to person, particularly in situations of crowding. Cases and deaths from meningitis among those displaced in Aceh and Pakistan have been documented (25,26). Prompt response with antimicrobial prophylaxis, as occurred in Aceh and Pakistan, can interrupt transmission. Large outbreaks have not been recently reported in disaster-affected populations but are well-documented in populations displaced by conflict (34).

Acute respiratory infections (ARI) are a major cause of illness and death among displaced populations, particularly in children <5 years of age. Lack of access to health services and to antimicrobial agents for treatment further increases the risk for death from ARI. Risk factors among displaced persons include crowding, exposure to indoor cooking using open flame, and poor nutrition. The reported incidence of ARI increased 4-fold in Nicaragua in the 30 days after Hurricane Mitch in 1998 (35), and ARI accounted for the highest number of cases and deaths among those displaced by the tsunami in Aceh in 2004 (26) and by the 2005 earthquake in Pakistan (25).