托福阅读材料(173)：汉坦病毒

　　托福阅读背景材料/知识之汉坦病毒，更多托福阅读背景材料/知识尽在新东方在线托福考试频道！

　　生化危机也许并不止局限在屏幕上，虽然目前科技比较发达，但是，在医学方面，还存在着很多未知领域。近日，加州公园爆发致命病毒，大约1万名游客承受风险。

　　Some 10,000 people who stayed in tent cabins at Yosemite National Park this summer may be at risk for the deadly rodent-borne hantavirus, the U.S. Centers for Disease Control and Prevention said on Friday.

　　The CDC urged lab testing of patients who exhibit symptoms consistent with the lung disease, hantavirus pulmonary syndrome, after a stay at the California park between June and August and recommended that doctors notify state health departments when it is found.

　　Two men have died from hantavirus linked to the Yosemite outbreak and four others were sickened but survived, while the CDC said additional suspected cases were being investigated from "multiple health jurisdictions."

　　Most of the victims were believed to have been infected while staying in one of 91 "Signature" tent-style cabins in Yosemite's popular Curry Village camping area.

　　"An estimated 10,000 persons stayed in the 'Signature Tent Cabins' from June 10 through August 24, 2012," the CDC said. "People who stayed in the tents between June 10 and August 24 may be at risk of developing HPS in the next six weeks."

　　Yosemite officials earlier this week shut down all 91 of the insulated tent cabins after finding deer mice, which carry the disease and can burrow through holes the size of pencil erasers, nesting between the double walls.

　　Park authorities said on Friday that they had contacted approximately 3,000 parties of visitors who stayed in the tent cabins since mid-June, advising them to seek immediate medical attention if they have symptoms of hantavirus.

　　Nearly 4 million people visit Yosemite, one of the nation's most popular national parks, each year, attracted to the its dramatic scenery and hiking trails. Roughly 70 percent of those visitors congregate in Yosemite Valley, where Curry Village is located.

　　The virus starts out causing flu-like symptoms, including headache, fever, muscle ache, shortness of breath and cough, and can lead to severe breathing difficulties and death.

　　The incubation period for the virus is typically two to four weeks after exposure, the CDC said, with a range between a few days and six weeks. Just over a third of cases are fatal.

　　据新华社美国疾病控制和预防中心8月31日说，大约1万名今年夏天在加利福尼亚州约塞米蒂国家公园露营的人承受风险，可能感染汉坦病毒。这一机构建议，近期有露营经历的民众如果出现流行性感冒症状，立即就医。美国疾控中心说，游客如果今年6月至8月在约塞米蒂国家公园柯里村“签名帐篷小屋”度假，有感染汉坦病毒的风险。

　　这一机构说，两人已经因为感染这一病毒死亡，另外4人发病，一些疑似病例正处于确诊阶段。大部分患者据信在“签名帐篷小屋”感染病毒。“据估计，大约1万人6月10日至8月24日之间入住"签名帐篷小屋"，”疾控中心说，“这段时间入住那些帐篷的人有在今后6周内出现汉坦病毒肺综合征症状的风险。”

　　汉坦病毒肺综合征由汉坦病毒引起，往往通过像鹿鼠这样的小型哺乳动物的排泄物、唾液等传播。汉坦病毒肺综合征患者早期可能出现类似感冒的症状，比如发热、头疼和常见于大腿、臀部及背部的疼痛。早期症状出现2至7天后，部分患者会出现呼吸困难，严重者甚至死亡。

　　汉坦病毒感染难于早期诊断，目前也没有相应的抗病毒治疗药物。根据美国疾病控制和预防中心的统计，全美自1993年以来共发现587个汉坦病毒肺综合征病例，其中三分之一患者死亡。

　　约塞米蒂是加州知名国家公园，尤其受攀岩者和家庭露营者欢迎，每年接待美国和来自世界各地的游客超过370万人次。