VOA标准英语2011--Scientists Infect Mosquitoes to Stop Den

Scientists Infect Mosquitoes to Stop Dengue

Australian researchers report success in attacking the insects that carry the dengue virus, a rarely fatal disease that nonetheless takes a huge toll¹ in sickness and economic loss in the tropical areas where it is endemic.
There's no vaccine² or even a specific treatment for the virus.
The World Health Organization says there may be 50 million dengue infections each year and 40 percent of the world's population is at risk.
The dengue virus is carried by a mosquito called Aedes aegypti, which carries the disease from person to person. Researcher Scott Ritchie of James Cook University says anti-dengue efforts have focused mainly on mosquito control.
"And the only way to control it is through the use of pesticides³ and perhaps community education, and some of the mosquitoes are getting resistant⁴ to those pesticides, so we need something novel and different," Ritchie says.
That's what Ritchie and other scientists have been working on, and they report their results in two papers in the journal Nature.
The researchers describe how the Aedes aegypti mosquito can be infected with a bacteria called Wolbachia, which blocks the ability of the dengue virus to grow, so it can't be passed on to the next person the mosquito bites.
To simulate a real-world situation, they released Wolbachia-infected mosquitoes into an indoor test facility filled with uninfected mosquitoes. Within a few months, the anti-dengue infected insects completely dominated the mosquito population as the infected mosquitoes mated with the uninfected ones.
The researchers then moved from a simulated real-world test to an actual real-world test, releasing the infected mosquitoes in two isolated⁵ Australian towns.
Chief investigator⁶ Scott O'Neill of Monash University says that as the infected insects were released over period of weeks, they began to dominate the native, uninfected mosquitoes.
"And then most importantly, once the release has stopped, Wolbachia continued to increase until the experiments came to a conclusion at the end of the wet season. And about that time we can see that we have almost complete penetration⁷ of the Wolbachia infection into the mosquito population at these sites."
Another team member, Ary Hoffman of the University of Melbourne, says the researchers next need to release Wolbachia into an area where dengue is endemic, to see if it actually prevents the disease.
"And until we go through that exercise, we would have to be cautious," Hoffman says. "So I think it's early...You know, at the moment we're very hopeful. But before we get to the stage where we can say, hey, Wolbachia can control dengue, that's a different matter, that's a bit down the track."
In a commentary also published in Nature, Johns Hopkins scientist Jason Rasgon says the Australia research heralds⁸ what he calls "the beginning of a new era in the control of mosquito-borne diseases," and suggests a strategy that could also apply to malaria⁹.
Rasgon also notes that effects on the ecosystem¹⁰ should be minimal¹¹ because the mosquitoes were changed, not eliminated.

1 toll   

n.过路(桥)费；损失，伤亡人数；v.敲(钟)

参考例句：

• The hailstone took a heavy toll of the crops in our village last night.昨晚那场冰雹损坏了我们村的庄稼。
• The war took a heavy toll of human life.这次战争夺去了许多人的生命。

2 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。

3 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

4 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。

5 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。

6 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

7 penetration   

n.穿透，穿人，渗透

参考例句：

• He is a man of penetration.他是一个富有洞察力的人。
• Our aim is to achieve greater market penetration.我们的目标是进一步打入市场。

8 heralds   

n.使者( herald的名词复数 )；预报者；预兆；传令官v.预示( herald的第三人称单数 )；宣布（好或重要）

参考例句：

• The song of birds heralds the approach of spring. 百鸟齐鸣报春到。 来自《现代英汉综合大词典》
• The wind sweeping through the tower heralds a rising storm in the mountain. 山雨欲来风满楼。 来自《现代汉英综合大词典》

9 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。

10 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

11 minimal   

adj.尽可能少的，最小的

参考例句：

• They referred to this kind of art as minimal art.他们把这种艺术叫微型艺术。
• I stayed with friends, so my expenses were minimal.我住在朋友家，所以我的花费很小。