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南非爆发“裂谷热”疫病,当局承诺游客健康无碍

kira86 于2010-07-12发布 l 已有人浏览
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South Africa Faces an Outbreak of Rift Valley Fever高速下载 This is the VOA Special English Development Report
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South Africa Faces an Outbreak of Rift Valley Fever


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This is the VOA Special English Development Report.

Rift Valley fever mainly affects farm animals. But the virus can also infect humans, and South Africa has been experiencing an outbreak. The National Institute for Communicable Diseases reported two hundred twenty-five confirmed human cases as of July second. Twenty-five of the people died.

South Africa launched an expanded program to watch for public health threats during the World Cup. Health officials said last week that there were no cases of Rift Valley fever in tourists. The majority of farms affected by the outbreak are outside areas generally visited by travelers.

Most of the cases have been found in farm workers in two provinces: Free State and Northern Cape.

Most human infections with Rift Valley fever are caused by direct or indirect contact with diseased animals. Infected mosquitoes can also pass the disease to humans. So can drinking unpasteurized or uncooked milk from infected animals.

Most human cases of the disease are minor. Some patients do not get sick at all. Others may get flu-like symptoms such as fever, muscle and joint pain and headaches. Patients normally recover within seven days.

But patients with more severe forms can go blind. Some develop encephalitis, a brain disease that can lead to headaches, coma or seizures. And some patients bleed to death.

The World Health Organization says Rift Valley fever was first discovered in Kenya in nineteen thirty-one. In the year two thousand, it was identified in Saudi Arabia and Yemen. These were the first reported cases of Rift Valley fever outside of Africa.

Current vaccines to protect against Rift Valley fever are limited to use in animals. But researchers are working to develop the first human vaccine.

In a new study, scientists in the United States tested vaccines made with two kinds of inactivated virus. They said tests in mice showed that their new vaccines are safer than live-virus vaccines and appear to work just as well. Using live virus in vaccines can increase the risks.

The researchers are at the University of Pittsburgh and the University of North Carolina. Their study appeared in the journal PLoS Neglected Tropical Diseases, published by the Public Library of Science,.

And that's the VOA Special English Development Report, written by June Simms. You can read and listen to all of our reports at 51voa.com. You can also find us on Facebook, Twitter, YouTube and iTunes at VOA Learning English. I'm Steve Ember.

何为裂谷热? 裂谷热(Rift Valley Fever,简称RVF)-- 一种由裂谷热病毒引起的急性发热性动物源性疾病(本来在动物间流行,但偶然情况下引起人类发病)。
  主要经蚊叮咬或通过接触染疫动物传播给人,多发生于大雨季节。病毒性出血热可导致动物和人的严重疾病,引起严重的公共卫生问题和因牲畜减少而导致的经济下降问题。
  人感染病毒2-6天后,突然出现流感样疾病表现,发热、头痛、肌肉痛、背痛,一些病人可发展为颈硬、畏光和呕吐,在早期,这类病人可能被误诊为脑膜炎。持续4-7天,在针对感染的免疫反应IgM和IgG抗体可以检测到后,病毒血症消失。人类染上裂谷热病毒后病死率通常较低,但每当洪水季节来临,在肯尼亚和索马里等非洲国家则会有数百人死于该病。
  大多数病例表现相对轻微,少部分病例发展为极为严重疾病,可有以下症状之一:眼病(约0.5-2%)、脑膜脑炎或出血热(小于1%)。眼病(特征性表现为视网膜病损)通常在第一症状出现后1-3周内起病,当病损在视网膜中区,将会出现一定程度的永久性视力减退。其他综合症表现为急性神经系统疾病,脑膜脑炎,一般在1-3周内出现。仅有眼病或脑膜脑炎时不容易发生死亡。
  裂谷热可表现为出血热,起病后2-4天,病人出现严重肝病,伴黄疸和出血现象,如呕血、便血、进行性紫癜(皮肤出血引起的皮疹),牙龈出血。伴随裂谷热出血热综合症的病人可保持病毒血症长达10天,出血病例病死率大约为50%。大多数死亡发生于出血热病例。在不同的流行病学文献中,总的病死率差异很大,但均小于1%。

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