3-15 西尼罗河病毒（在线收听）

West Nile Virus

West Nile virus(WNV) was first isolated from a febrile¹ adult woman in the West Nile District of Uganda in 1937. The virus became recognized as a cause of severe human meningoencephalitis² in elderly patients during an outbreak in Israel in 1957.

WNV has been described in Africa, Europe, the Middle East, west and central Asia, Oceania, and most recently, North America. The first appearance of WNV in North America in 1999, with encephalitis³ reported in humans and horses, and the subsequent spread in the United States may be an important milestone in the evolving history of this virus. Experts believe WNV is established as a seasonal epidemic in North America that flares up⁴ in the summer and continues into the fall.

WNV affects the central nervous system. The most serious manifestation⁵ of WNV infection is fatal encephalitis. Its symptoms vary. Approximately 80 percent of people who are infected with WNV will not show any symptoms at all. Up to 20 percent of the people who become infected will display mild symptoms, including fever, headache, and body aches, nausea⁶, vomiting, and sometimes swollen lymph glands⁷ or a skin rash on the chest, stomach and back. Symptoms typically last a few days. About one in 150 people infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor⁸, disorientation⁹, coma¹⁰, tremors¹¹, convulsions¹², muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological¹³ effects may be permanent.

Generally, WNV is spread by the bite of an infected mosquito. People typically develop symptoms between 3 and 14 days after they are bitten by the infected mosquito. There is no specific treatment for WNV infection.

注释：

1. febrile [5fi:brail] adj. 发热的；发烧的

2. meningoencephalitis [mi5niN^EuEn7sefE5laitis] n. [医]脑膜脑炎

3. encephalitis [en7sefE5laitis] n. [医] 脑炎

4. flare up（尤指短时间平静后）突然爆发；剧化

5. manifestation [7mAnifes5teiFEn] n. 表现；表现形式；现象

6. nausea [5nC:ziE] n. 恶心

7. lymph gland [解] 淋巴结（俗名淋巴腺）

8. stupor [5stju:pE(r)] n. 昏迷，不省人事

9. disorientation [dis7C:riEn5teiFEn] n. 迷向；迷失知觉

10. coma [5kEumE] n. [医] 昏迷

11. tremor [5tremE(r)] n. 震颤；颤抖

12. convulsion [kEn5vQlFEn] n. [常作～s] 惊厥，抽搐

13. neurological [njuErEu5lCdVikEl] adj. 神经病学的

西尼罗河病毒

　　西尼罗河病毒于1937年在乌干达西尼罗河地区一位发烧的成年妇女身上首次分离出来。此病毒被认为是1957年爆发于以色列的一次老年病人严重脑膜脑炎的病因。

　　西尼罗河病毒在非洲、欧洲、中东、西亚和中亚、大洋洲以及最近在北美都发现过。1999年，西尼罗河病毒在北美第一次出现，致使人和马罹患脑炎，随后在美国蔓延，这可说是该病毒发展史上一次重要的里程碑事件。专家相信，西尼罗河病毒在北美已经演变成一种季节性传染病，夏天发作，延续到秋天。

　　西尼罗河病毒影响中枢神经系统。感染该病毒最严重的表现是致命的脑炎。它的症状因人而异。大约80％的感染者根本没有任何症状，至多20％的感染者表现出轻微的症状，包括发烧、头痛、浑身疼痛、恶心、呕吐，有时出现淋巴腺肿大或胸部、腹部和背部出现皮疹，症状一般持续几天。而大约每150名感染者中会有1人发展成严重疾病。严重的症状包括高烧、头痛、颈部发僵、昏迷、方向知觉丧失、失去知觉、颤栗、抽搐、肌肉无力、失明、麻木和瘫痪。这些症状可能持续几个星期，对神经系统的影响可能是永久性的。

　　一般而言，西尼罗河病毒是由受到感染的蚊子传播的。人通常在被毒蚊叮过3至14天之内发病。目前对西尼罗河病毒感染还没有特定的治疗方法。