VOA慢速英语2010-SCIENCE IN THE NEWS - Nations Work Toward

FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I’m Faith Lapidus.

BOB DOUGHTY¹: And I’m Bob Doughty. Today we will tell about the disease malaria² and efforts to defeat it. Scientists say progress in medical research could reduce the number and severity of malaria cases worldwide.

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FAITH LAPIDUS: World Malaria Day activities are planned in many countries this Sunday. The events will call attention to the disease and international efforts against it.

This is the third year that World Malaria Day has been observed. It is also an important year in the fight against malaria. The international malaria community has set the end of twenty-ten as its target for meeting the first in a series of goals.

A volunteer in Port-au-Prince treats a Haitian child for malaria

One of the goals is to provide protection, medical diagnosis³ and treatment for every person at risk of malaria. A second goal is for the number of malaria cases and deaths to be reduced by fifty percent or more from the number reported in two thousand.

BOB DOUGHTY: The World Health Organization estimates that more than three billion people live in areas where malaria is a threat. That represents more than half of the world’s population. America’s Centers for Disease Control and Prevention says the disease will infect three hundred fifty million to five hundred million people around the world this year. Each year, malaria kills about nine hundred thousand people worldwide. Those surviving are often left brain damaged, blind or with hearing loss.

FAITH LAPIDUS: Most cases of malaria are in African countries, south of one of the world’s biggest deserts – The Sahara. The World Health Organization says the disease is responsible for one in five childhood deaths there. Malaria kills about two hundred thousand children in Africa every year, an average of one every thirty seconds.

Malaria is also a threat to people living in parts of Asia, Central and South America, the Middle East, and southeastern Europe. People from malaria-free countries who visit areas with high rates of malaria are also very much at risk. This is because their bodies have little or no resistance to the disease.

The Plasmodium parasite⁴, center, among blood cells

BOB DOUGHTY: The cause of malaria is a parasite called Plasmodium. Mosquitoes infected with Plasmodium spread the disease to human beings through mosquito bites. The parasites⁵ reproduce in the human liver, and then infect the red blood cells. After they enter the blood cells, they reproduce again. As they do this, they destroy the cells.

Signs of the disease appear in victims ten to fifteen days after they are bitten. People with malaria develop a high body temperature. They also can become weak, expel material from the stomach, and suffer pain in the head or muscles. If not treated, malaria can make the victim very sick and even cause death.

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FAITH LAPIDUS: Late last year, researchers in the United States met to discuss developments in malaria research. One sign of hope is a new way to make the natural defenses of mosquitoes resistant⁶ to the Plasmodium parasite.

George Dimopoulos is an associate professor at the Johns Hopkins Malaria Research Institute. His team used a method called transient gene⁷ silencing to change the genetic⁸ structure of the three mosquito species responsible for spreading malaria. The genetic changes cause the bodies of the insects to attack the Plasmodium parasite, blocking its development.

BOB DOUGHTY: Gregory Glass is a professor with the John Hopkins Bloomberg School of Public Health. His team used satellite imaging to observe mosquito populations in Africa. The closer one lives to places where mosquitoes reproduce, the greater the risk of getting malaria.

Anopheles is one of the mosquitoes that carries the malaria parasite

Professor Glass says the satellite imaging helps researchers identify which areas face the greatest risk. He says it also shows where to send much-needed medicines, insecticide products and protective mosquito nets.

FAITH LAPIDUS: The Malaria Institute at Macha in southern Zambia is a living laboratory for the study of mosquito and human behavior. There, researchers are developing a test that uses human saliva⁹ instead of blood to find those infected with malaria. The researchers say the test will make it easier to identify and contain the disease, especially in children. It would also be helpful in areas like southern Africa, where people often do not show signs of the disease.

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BOB DOUGHTY:

For years, researchers have been working to develop a vaccine¹⁰ against malaria. Those efforts have greatly increased in recent years. There are now more than fifty experimental vaccines¹¹ in existence.

The world’s largest malaria vaccine study began last year in seven African countries. It is the result of more than twenty years of research and ten years of clinical testing. The study is to involve up to sixteen thousand children. They live in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania.

GlaxoSmithKline Biologicals developed the vaccine, known as RTS,S. It is the first malaria vaccine candidate to have large success during early testing. It is also the first vaccine designed mainly for use in Africa.

FAITH LAPIDUS: A recent study showed that RTS,S reduced clinical cases of malaria by fifty-three percent over an eight month follow-up period. In another study, the vaccine was effective in reducing clinical malaria by thirty-five percent. It also reduced cases of severe malaria by forty-nine percent.

Two weeks ago, a Dutch drug-maker, Crucell, announced it will work with GlaxoSmithKline to jointly¹² develop a new malaria vaccine candidate. The vaccine candidate is to be made from two drugs the companies are developing separately. Crucell says studies have shown the drugs may work better when combined than they do independently.

BOB DOUGHTY: Last year, another drug company, Sanaria, won a Vaccine Industry Excellence¹³ Award for Best Early Stage Vaccine for its malaria vaccine. The Sanaria vaccine is unlike other malaria vaccines being developed. It is a live vaccine, made of a weakened version of the whole malaria parasite.

Scientists at Sanaria use non-malaria carrying mosquitoes to develop their vaccine. They feed the insects blood containing the malaria parasite. They then use radiation to weaken the parasite, which is then harvested for the vaccine.

In an earlier study, the scientists at Sanaria used live mosquitoes to deliver the vaccine. Thirteen of fourteen volunteers were completely protected against malaria after receiving the vaccine. They also remained protected for at least ten months. Sanaria is now preparing to ask the United States Food and Drug Administration for approval to begin federal testing of the vaccine.

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FAITH LAPIDUS: For now, the main effort to control malaria involves treatment of bed nets and indoor living areas with insecticides -- products used to kill insects.

The World Health Organization says insecticide use has greatly reduced the number of malaria cases. The W.H.O. says insecticide-treated bed nets have been shown to reduce the number of malaria cases by fifty percent and the infection rate by ninety percent.

The United Nations agency released its World Malaria Report in December. The report said home ownership of insecticide-treated nets had reached fifty percent in thirteen of the thirty-five African countries with the highest cases of malaria. It also said more than one third of all countries at risk of malaria reported a drop in cases of more than fifty percent.

BOB DOUGHTY: Early identification and drug treatment of malaria can reduce the severity of the disease and prevent death. The anti-malarial drug Chloroquine was widely used until recent years when the malaria parasite became resistant to the drug. Now, the World Health Organization advises use of Artemisinin-based combination treatments, or ACTs, for malaria patients.

The W.H.O. says the international community is now in a position to defeat malaria. It says that, with the use of insecticides, better testing and drug treatments, the world could reach its goal of zero malaria deaths by twenty fifteen. Still, it says, there is an immediate¹⁴ need for the international community to continue and increase its investment in the fight against malaria.

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FAITH LAPIDUS: This SCIENCE IN THE NEWS was written by June Simms. Our producer was Mario Ritter. I’m Faith Lapidus.

BOB DOUGHTY: And, I’m Bob Doughty. Listen again next week for more news about science, in Special English, on the Voice of America.

 

1 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

2 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

3 diagnosis   

n.诊断，诊断结果，调查分析，判断

参考例句：

• His symptoms gave no obvious pointer to a possible diagnosis.他的症状无法作出明确的诊断。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做一次彻底的调查分析。

4 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

5 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

6 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。

7 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

8 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

9 saliva   

n.唾液，口水

参考例句：

• He wiped a dribble of saliva from his chin.他擦掉了下巴上的几滴口水。
• Saliva dribbled from the baby's mouth.唾液从婴儿的嘴里流了出来。

10 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

11 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

12 jointly   

ad.联合地，共同地

参考例句：

• Tenants are jointly and severally liable for payment of the rent. 租金由承租人共同且分别承担。
• She owns the house jointly with her husband. 她和丈夫共同拥有这所房子。

13 excellence   

n.优秀，杰出，(pl.)优点，美德

参考例句：

• His art has reached a high degree of excellence.他的艺术已达到炉火纯青的地步。
• My performance is far below excellence.我的表演离优秀还差得远呢。

14 immediate   

adj.立即的；直接的，最接近的；紧靠的

参考例句：

• His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
• We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。