VOA慢速英语2015 土地用途的改变可能会增加灾祸的发生

AS IT IS 2015-03-31 Land-Use Changes May Increase Risk of Plague 土地用途的改变可能会增加灾祸的发生

Conversion¹ of forests to agricultural use create habitats for small rats that carry disease such as plague. (Photo by Douglas McCauley)

Efforts to increase food production in Africa may be increasing the risk of plague infection. Plague has been killing² people for hundreds of years. A new report looks at efforts to clear land for farming in natural, undeveloped areas of Tanzania. The report links the development of natural lands into croplands to a sharp increase in the number of rats. It warns the animals often carry insects infected with plague.

Many people become frightened when they hear the word “plague.” One of the most famous periods of plague death was known as the “Black Death.” It was a time 700 years ago when the disease killed more than 25 million people in Europe.

Health officials do not believe plague will kill many people in Africa. But they are worried about the rising number of plague infections. Thirty to 60 percent of those infected will die if they are not given medicine.

Plague is caused by bacterium³. It is passed between animals and humans through the bite of an inflected flea⁴ or by touching⁵ an infected animal. Rats often carry fleas⁶. The insects feed on the blood of an infected rat.

There are three forms of plague. The most common is bubonic plague. This was the disease that spread in Europe during the 14th century. Bubonic plague causes enlargement of lymph nodes. The lymphatic system is the part of the body’s natural defense⁷ system against disease.

If the plague infection is not treated, the bacteria can reach the lungs. Then, the person may develop pneumonic⁸ plague. This is the least common but most aggressive form of the disease. It can be easily spread through small droplets⁹ expelled from the person’s nose or mouth. A person infected with bubonic plague cannot infect others.

The World Health Organization says pneumonic plague is one of the most deadly infectious diseases. People suffer high body temperature, shaking, pain, weakness, and muscle and joint¹⁰ pain within two to three days of being infected.

Antibiotic¹¹ drugs can cure the disease. But the infected individual must take them very quickly, because pneumonic plague can kill people within 24 hours after infection. The WHO says only a small number of reported cases are of the pneumonic form.

Kristofer Helgen is with the Smithsonian Institution’s Museum of Natural History in Washington, D.C. He helped to write the new report. It was published online in the American Journal of Tropical Medicine and Hygiene¹². He spoke¹³ to VOA about the disease.

“It maybe surprises people to learn that plague remains¹⁴ a public health concern in various parts of the world -- especially in Africa south of the Sahara. Plague circulates in small mammals and rodents¹⁶. And when the conditions are right, it’s a disease that can spread to people and it can still be a deadly disease. Now, plague is a disease that is treatable with antibiotics¹⁷. And in that regard, it’s considerably¹⁸ maybe less scary, less alarming than other emerging diseases like Ebola. But we should remember that this is a disease that is still on the ground in Africa and remains a public health concern.”

Mr. Helgen says the amount of farmland in northern Tanzania has risen sharply in recent years. By his estimate, the croplands have expanded by 70 percent. He and other researchers also attempted to estimate the number of rats in areas where maize¹⁹ was planted. They found the rat population doubled in those areas, compared to neighboring land that had not been developed for agriculture.

Mr. Helgen says that as the amount of farmland increases, so does the number of rats. He notes that the animals and people often live in the same areas, which makes it easier for plague to spread.

“And this is an animal that we often will call a commensal rodent¹⁵ species. And literally²⁰ that word commensal means ‘eating from the same table’ -- in other words, the notion that this is a rat that does go into peoples’ houses and villages and interacts with people in their living spaces.”

He notes that rats have a major effect on peoples’ lives. The animals eat people’s food, spread disease and make it more difficult for farmers to succeed.

The plague never completely disappears. It may stay in the wild for 10 or 20 years. Then, something happens and the number of rats increases. The disease then begins to spread in agricultural areas, then to towns and cities. Many people in an area may die, but the disease rarely spreads outside a country. Only people within a limited area are infected. When the number of cases begins to decline, scientists will say “the outbreak has been contained.”

The World Health Organization says people should not be afraid of the plague. It says scientists have developed modern and effective ways to prevent, treat and cure the ancient disease.

Words in This Story

infect – v. to cause (someone or something) to become sick or affected²¹ by disease

bacterium – n. any one of a group of very small living things that often cause disease (usually plural)

bubonic (plague) – n. a very serious disease that killed many people in the Middle Ages

circulate – v. to go or spread from one person, place or thing to another

on the ground – idiomatic²² expression events where things are actually happening; not at a distance. Describes a situation viewed up-close or the people in a position to view a situation up-close, in detail; typically used by someone not close to the situation being discussed

notion – n. an idea or opinion

interact – v. to come together and have an effect on each other; often used with the word “with”

1 conversion   

n.转化，转换，转变

参考例句：

• He underwent quite a conversion.他彻底变了。
• Waste conversion is a part of the production process.废物处理是生产过程的一个组成部分。

2 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

3 bacterium   

n.(pl.)bacteria 细菌

参考例句：

• The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
• A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。

4 flea   

n.跳蚤

参考例句：

• I'll put a flea in his ear if he bothers me once more.如果他再来打扰的话，我就要对他不客气了。
• Hunter has an interest in prowling around a flea market.亨特对逛跳蚤市场很感兴趣。

5 touching   

adj.动人的，使人感伤的

参考例句：

• It was a touching sight.这是一幅动人的景象。
• His letter was touching.他的信很感人。

6 fleas   

n.跳蚤( flea的名词复数 )；爱财如命；没好气地（拒绝某人的要求）

参考例句：

• The dog has fleas. 这条狗有跳蚤。
• Nothing must be done hastily but killing of fleas. 除非要捉跳蚤，做事不可匆忙。 来自《简明英汉词典》

7 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

8 pneumonic   

adj.肺的；肺炎的

参考例句：

• The chill superinduced a pneumonic condition. 受寒并发了肺炎。 来自《现代英汉综合大词典》
• The fatality rate of pneumonic plague a staggering 95 percent. 肺鼠疫的死亡率是达到惊人95％。 来自互联网

9 droplets   

n.小滴( droplet的名词复数 )

参考例句：

• Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
• In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反，从人嘴里呼出的烟则包含相当大的水滴，所以呈白色。 来自辞典例句

10 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

11 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

12 hygiene   

n.健康法，卫生学 （a.hygienic）

参考例句：

• Their course of study includes elementary hygiene and medical theory.他们的课程包括基础卫生学和医疗知识。
• He's going to give us a lecture on public hygiene.他要给我们作关于公共卫生方面的报告。

13 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

14 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

15 rodent   

n.啮齿动物；adj.啮齿目的

参考例句：

• When there is a full moon,this nocturnal rodent is careful to stay in its burrow.月圆之夜，这种夜间活动的啮齿类动物会小心地呆在地洞里不出来。
• This small rodent can scoop out a long,narrow tunnel in a very short time.这种小啮齿动物能在很短的时间里挖出一条又长又窄的地道来。

16 rodents   

n.啮齿目动物( rodent的名词复数 )

参考例句：

• Rodents carry diseases and are generally regarded as pests. 啮齿目动物传播疾病，常被当作害虫对待。 来自《简明英汉词典》
• Some wild rodents in Africa also harbor the virus. 在非洲，有些野生啮齿动物也是储毒者。 来自辞典例句

17 antibiotics   

n.（用作复数）抗生素；（用作单数）抗生物质的研究；抗生素，抗菌素( antibiotic的名词复数 )

参考例句：

• the discovery of antibiotics in the 20th century 20世纪抗生素的发现
• The doctor gave me a prescription for antibiotics. 医生给我开了抗生素。

18 considerably   

adv.极大地；相当大地；在很大程度上

参考例句：

• The economic situation has changed considerably.经济形势已发生了相当大的变化。
• The gap has narrowed considerably.分歧大大缩小了。

19 maize   

n.玉米

参考例句：

• There's a field planted with maize behind the house.房子后面有一块玉米地。
• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。

20 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

21 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

22 idiomatic   

adj.成语的，符合语言习惯的

参考例句：

• In our reading we should always be alert for idiomatic expressions.我们在阅读过程中应经常注意惯用法。
• In his lecture,he bore down on the importance of idiomatic usage in a language.他在演讲中着重强调了语言中习惯用法的重要性。