>>>沪江汶川地震专题
【与水相关的传染病】

安全洁净的水源，可能会因为一场自然灾害而被破坏。饮用水被污染后，腹泻类疾病可能爆发，洪水以及相关的流离失所之后也有此类的疫情报告。在2004年孟加拉国洪水后的一次爆发中，超过17000个病例出现腹泻症状；霍乱弧菌（小川血清型和稻叶血清型）、产毒大肠杆菌都曾被检出（13）

1998年，西孟加拉的一次霍乱大爆发（小川血清型，超过1.6万个病例）也被认为与之前的洪水有关（14）；2000年1月到3月在莫桑比克的洪水也导致了腹泻病例的增多。

在1992-1993年印度尼西亚进行的一次大规模研究中，洪水被确定为由甲型副伤寒沙门氏菌导致的腹泻时疫的重要风险因素（16）。 2001-2003年印度尼西亚另一个有关小隐孢子虫感染的风险因素的评估研究中，与对照组相比，案例中的病人接触洪水后得病的几率是4倍以上（17）。

自然灾害后腹泻时疫爆发的风险在发展中国家比在发达国家更高（8，11）。在印度尼西亚的亚齐省，2004年12月的海啸两周后在扎朗镇的一次快速健康评测中发现，幸存者中100%曾从未得到保护的水井中饮水，而此前的两周中85%的居民报告腹泻（18）。（译者：地名译名据新华社资料库，下同）

在巴基斯坦的穆扎法拉巴德，2005年一次地震后，居住在一个事先没有规划、装备很差的营地中的1800人中爆发了严重的水性腹泻。这次爆发共有超过750个病例，其中大部分是成人。而在提供了充足的饮用水和卫生方便设施之后，疫情得到了控制（19）。

在美国，艾里森和卡特里娜飓风之后也有腹泻疾病的记录。在卡特里娜飓风中被撤离的人群中，曾检查出诺罗病毒，沙门氏菌，以及会产生毒素的霍乱胡菌等。

A型（甲型）和E型肝炎（戊型肝炎）主要通过粪-口途径传播，也与缺乏安全的水源和卫生设施有关。A型肝炎是大多数发展中国家的一种地方病，而大多数孩子因为在很小的时候曾患病而具有免疫性。因此，A型肝炎大规模爆发的几率通常就低一些。而在有E型肝炎病例的地区，该疾病通常会随暴雨和洪水的发生而爆发；这种疾病通常比较温和，而且有较强局限性，但是孕妇的死亡率可能高达百分之二十五。在2005年巴基斯坦地震后，零星的E型肝炎在那些缺乏安全水源的地区时有发生。在流离失所的难民中，发现了超过1200例急性黄疸，其中很多被确认为E型肝炎。印尼的Aceh在2004年12月海啸之后，也有集中的A型和E型肝炎病例。

细螺旋体病是一种有流行危险、通过动物传染的细菌性疾病，并可通过直接接触受污染的水进行传播。啮齿动物（鼠类）的尿液中含有大量的细螺旋体病菌，传播途径包括皮肤和粘膜与水接触、与潮湿的土壤及蔬果接触（如甘蔗）、或接触被这种尿液污染的泥巴。洪水后啮齿动物的扩散，以及人类与啮齿动物共占高地后带来的近距离接触，加剧了这种病菌的传播。2001 年中国台湾的 Nali 台风（27）、2000 年印度孟买的洪水（28）、1998 年阿根廷的洪水（29）以及 1997 年苏联克拉斯诺达尔（30），灾难过后都伴随着细螺旋体病的爆发。1996 年巴西发生了与洪水关联的细螺旋体病传染，之后的地域分析显示，在里约热内卢遭受洪水的区域，细螺旋体病的发病率增加了两倍之多（31）。

Water-related Communicable Diseases
Access to safe water can be jeopardized by a natural disaster. Diarrheal disease outbreaks can occur after drinking water has been contaminated and have been reported after flooding and related displacement. An outbreak of diarrheal disease after flooding in Bangladesh in 2004 involved >17,000 cases; Vibrio cholerae (O1 Ogawa and O1 Inaba) and enterotoxigenic Escherichia coli were isolated (13). A large (>16,000 cases) cholera epidemic (O1 Ogawa) in West Bengal in 1998 was attributed to preceding floods (14), and floods in Mozambique in January–March 2000 led to an increase in the incidence of diarrhea (15).

In a large study undertaken in Indonesia in 1992–1993, flooding was identified as a significant risk factor for diarrheal illnesses caused by Salmonella enterica serotype Paratyphi A (paratyphoid fever) (16). In a separate evaluation of risk factors for infection with Cryptosporidium parvum in Indonesia in 2001–2003, case-patients were >4× more likely than controls to have been exposed to flooding (17).

The risk for diarrheal disease outbreaks following natural disasters is higher in developing countries than in industrialized countries (8,11). In Aceh Province, Indonesia, a rapid health assessment in the town of Calang 2 weeks after the December 2004 tsunami found that 100% of the survivors drank from unprotected wells and that 85% of residents reported diarrhea in the previous 2 weeks (18). In Muzaffarabad, Pakistan, an outbreak of acute watery diarrhea occurred in an unplanned, poorly equipped camp of 1,800 persons after the 2005 earthquake. The outbreak involved >750 cases, mostly in adults, and was controlled after adequate water and sanitation facilities were provided (19). In the United States, diarrheal illness was noted after Hurricanes Allison (20) and Katrina (21–23), and norovirus, Salmonella, and toxigenic and nontoxigenic V. cholerae were confirmed among Katrina evacuees.

Hepatitis A and E are also transmitted by the fecal-oral route, in association with lack of access to safe water and sanitation. Hepatitis A is endemic in most developing countries, and most children are exposed and develop immunity at an early age. As a result, the risk for large outbreaks is usually low in these settings. In hepatitis E–endemic areas, outbreaks frequently follow heavy rains and floods; the illness is generally mild and self-limited, but for pregnant women case-fatality rates can reach 25% (24). After the 2005 earthquake in Pakistan, sporadic hepatitis E cases and clusters were common in areas with poor access to safe water. Over 1,200 cases of acute jaundice, many confirmed as hepatitis E, occurred among the displaced (25). Clusters of both hepatitis A and hepatitis E were noted in Aceh after the December 2004 tsunami (26).

Leptospirosis is an epidemic-prone zoonotic bacterial disease that can be transmitted by direct contact with contaminated water. Rodents shed large amounts of leptospires in their urine, and transmission occurs through contact of the skin and mucous membranes with water, damp soil or vegetation (such as sugar cane), or mud contaminated with rodent urine. Flooding facilitates spread of the organism because of the proliferation of rodents and the proximity of rodents to humans on shared high ground. Outbreaks of leptospirosis occurred in Taiwan, Republic of China, associated with Typhoon Nali in 2001 (27); in Mumbai, India, after flooding in 2000 (28); in Argentina after flooding in 1998 (29); and in the Krasnodar region of the Russian Federation in 1997 (30). After a flooding-related outbreak of leptospirosis in Brazil in 1996, spatial analysis indicated that incidence rates of leptospirosis doubled inside the flood-prone areas of Rio de Janeiro (31).