VOA标准英语2014--Sex Matters for Sleeping Sickness Microbes

 

Sex Matters for Sleeping Sickness Microbes

Scientists are keeping a close eye on the mating habits of microscopic¹ organisms, including those that cause African sleeping sickness. They say what happens between two parasites³ can have major consequences for humans

Researcher Wendy Gibson said when it comes to single-cell parasites known as trypanosomes, sex matters. They had once been thought to reproduce by splitting in half. But scientists say they have a sex life. 

“This is important because if they can mate, it means that they can swap⁴ genes⁶ around. For example, if you’ve got a strain of parasite² that’s resistant⁷ to a drug and it mates with one that isn’t, then it can swap that gene⁵ into the one that’s sensitive to the drug. And then, of course, you’ve got a new parasite, effectively, that is also resistant to the drug. That’s dangerous,” she said.

Gibson is professor of protozoology at the University of Bristol.

“Sleeping sickness is a very nasty disease. It’s carried by tsetse flies in tropical Africa. And now, fortunately, the numbers, as recorded by the World Health Organization, have dropped to less than 10,000 recorded cases. But years ago it used to really devastate⁸ large populations,” she said.

She explained how the illness got its name.

“It’s called sleeping sickness because the parasite gets into the brain and causes people to go into a sort of semi-comatose state. So that they just appear to be sleeping all the time. And that stage of the disease you can only treat with some very unpleasant drugs. One of them is based on arsenic⁹. So you can imagine that that doesn’t do you any good”

Sleeping sickness has been on the decline due to early diagnosis¹⁰, thorough treatment and better control of the tsetse fly population. That’s good news. But Gibson said that a resurgence¹¹ is always possible.

“A colleague once described sleeping sickness to me as the sleeping dragon. It never goes away because the problem is that there are animal reservoirs of the disease. So even if you haven’t got humans with the disease in an area, it may still be circulating in animals, for example, cattle or wild animals. And of course the tsetse fly is feeding on those in keeping that cycle of transmission going. And it may then, if you’re unlucky, transfer back into the human population,” she said.

Gibson said it’s important to understand sexual reproduction in microbes.

“It’s one of the reasons why we’re worried about the next influenza¹² outbreak because influenza is caused by viruses, but they also recombine. OK, it’s not the same sexual reproduction process as we get in these parasites, but it’s the same intrinsic mechanism¹³ that you’ve got recombination of genes. And, of course, with flu, you get new recombinant strains. We don’t know how virulent¹⁴ they are and what kind of disease they’ll cause and how quickly they’ll spread.”

The study of mating microbes helps explain how diseases spread and how new strains are formed. That’s why what’s happening in Uganda is being closely watched.

“You’ve got in the north of the country the West African form of the disease and in the southeast you’ve got the East African form. The East African form has been spreading northwards. And one of the worries is that it will overlap¹⁵ with the West African form of the disease. Now, if those two parasites then mate together, obviously, we’re worried that they’ll create some sort of superbug that maybe cause more serious disease,” said Gibson.

Trypanosomes are part of a group of organisms known as protozoa. They also include microbes that cause such illnesses as leishmaniasis, which affects internal organs – giardiasis, an intestinal¹⁶ disorder¹⁷ – and trichomoniasis, which is a sexually transmitted disease.

1 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

2 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。

3 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。

4 swap   

n.交换；vt.交换，用...作交易

参考例句：

• I will swap you my bicycle for your radio.我想拿我的自行车换你的收音机。
• This comic was a swap that I got from Nick.这本漫画书是我从尼克那里换来的。

5 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。

6 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

7 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。

8 devastate   

v.使荒芜，破坏，压倒

参考例句：

• A few days before,a fire had devastated large parts of Windsor Castle.几天前，温莎城堡的大部分被一场大火烧毁。
• Earthquakes can also cause tsunamis,which devastate coastal regions.地震还引发海啸，它直接破坏海岸地区。

9 arsenic   

n.砒霜，砷；adj.砷的

参考例句：

• His wife poisoned him with arsenic.他的妻子用砒霜把他毒死了。
• Arsenic is a poison.砒霜是毒药。

10 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。

11 resurgence   

n.再起，复活，再现

参考例句：

• A resurgence of his grief swept over Nim.悲痛又涌上了尼姆的心头。
• Police say drugs traffickers are behind the resurgence of violence.警方说毒贩是暴力活动重新抬头的罪魁祸首。

12 influenza   

n.流行性感冒，流感

参考例句：

• They took steps to prevent the spread of influenza.他们采取措施
• Influenza is an infectious disease.流感是一种传染病。

13 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

14 virulent   

adj.有毒的，有恶意的，充满敌意的

参考例句：

• She is very virulent about her former employer.她对她过去的老板恨之入骨。
• I stood up for her despite the virulent criticism.尽管她遭到恶毒的批评，我还是维护她。

15 overlap   

v.重叠，与…交叠；n.重叠

参考例句：

• The overlap between the jacket and the trousers is not good.夹克和裤子重叠的部分不好看。
• Tiles overlap each other.屋瓦相互叠盖。

16 intestinal   

adj.肠的；肠壁；肠道细菌

参考例句：

• A few other conditions are in high intestinal obstruction. 其它少数情况是高位肠梗阻。 来自辞典例句
• This complication has occasionally occurred following the use of intestinal antiseptics. 这种并发症偶而发生在使用肠道抗菌剂上。 来自辞典例句

17 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。