新基因试验有助于发现食物中毒

New Genetic¹ Test Helps Find Food Poisoning

American scientists are using genetic markers to investigate food poisoning cases linked to romaine lettuce². The Associated Press reports that their use of genetic sequencing is completely changing the discovery of bacteria in food.

Genetic sequencing is being used to strengthen investigations³ and, in some cases, find links between what once seemed to be unrelated diseases. The technology also is uncovering once unknown causes of food poisoning.

One such example involved apples covered in caramel, a popular treat in the United States.

Up to now, scientists have been looking mainly at one bacteria: listeria. But the search is expanding. By the end of this year, laboratories in all 50 states are expected to also be using genetic sequencing for more common causes of food poisoning. That includes salmonella and the E. coli bacteria linked to the romaine lettuce outbreak.

The new technique is also helping⁴ disease scientists identify food contamination even before it causes people to get sick.

Lawyer Bill Marler has taken companies to court when their food products sicken people. He said the technique is changing how outbreaks are discovered.

Marler said the testing program is still young. He said it is too early to call genetic sequencing a success. But he said it may change how and when outbreaks are found.

The Centers for Disease Control and Prevention, or CDC, supports the program. It estimates that 48 million Americans get sick from food poisoning each year. And 3,000 of those people die from such infections.

The use of genetic sequencing involves something called whole genome sequencing, which has been used in biology for more than 20 years. A genome is a kind of genetic map. It contains all of the genetic information, or DNA⁵, about an organism. DNA is short for the term deoxyribonucleic acid.

The laboratory process identifies most of an organism’s DNA. And scientists use computer programs to compare the DNA of test specimens⁷ to see if they are the same as the organism and how resistant⁸ they are to current medicines.

The technique makes the lab studies faster, less costly⁹ and more automated¹¹, said Robert Tauxe, one of the CDC’s leading experts on food poisoning.

Plans are to use the technology against several bacteria that cause food poisoning. But to date, all of the tests have involved listeria. The bacteria causes around 1,600 cases of food poisoning nationwide each year. But it is a very deadly infection, killing¹² nearly one in five people who get it.

It can take weeks for people to develop signs of the disease. In the past, some patients died by the time health officials began to recognize the problem.

For nearly 15 years, from 1983-1997, only five listeria outbreaks were identified in the United States. They were relatively¹³ large, with an average of 54 cases for each outbreak.

That is how it was with other food poisoning outbreaks.

Tauxe said most foodborne outbreaks were found because they happened in one place, like a town with a popular eatery where people became sick.

Outbreaks were studied by asking people what they ate before they got sick. Investigators¹⁴ then compared notes to see what patients had in common.

But the science took a big step in the 1990s, after a major outbreak happened in the Seattle, Washington area. Four deaths and more than 700 other infections eventually were linked to undercooked hamburgers from a Jack¹⁵ in the Box restaurant. The meat contained the bacteria E. coli.

The outbreak led the CDC to develop a program that used a technique called pulsed-field gel electrophoresis. With this, investigators could look at a bacteria’s DNA in parts. The program helped health officials more easily link cases. But it was not perfect. It was unable to make exact matches and sometimes missed when cases were related.

Then came whole genome sequencing.

The CDC began using the technique in food poisoning investigations in 2013. In the beginning, state laboratories sent samples to a CDC laboratory in Georgia for testing. Now, the CDC is working to make the technology available in all 50 states.

I'm Alice Bryant.

Words in This Story

sequencing – gerund. determining the order of, especially nucleotides in DNA or RNA or amino acids in a protein.

lettuce – n. a plant that has large leaves that are eaten especially in salads

caramel – n. a light brown candy made from butter, sugar, and milk or cream

outbreak – v. a sudden start or increase of fighting or disease

contaminate – v. to make something dangerous, dirty, or impure¹⁶ by adding something harmful or undesirable¹⁷ to it

specimen⁶ – n. a small amount or piece of something that can be tested or examined

strain – n. a kind or sort of something

automate¹⁰ – v. to run or operate something by using machines, computers, or something else, instead of people to do the work

match – n. a person or thing that is an exact counterpart of another

1 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。

2 lettuce   

n.莴苣；生菜

参考例句：

• Get some lettuce and tomatoes so I can make a salad.买些莴苣和西红柿，我好做色拉。
• The lettuce is crisp and cold.莴苣松脆爽口。

3 investigations   

（正式的）调查( investigation的名词复数 )； 侦查； 科学研究； 学术研究

参考例句：

• His investigations were intensive and thorough but revealed nothing. 他进行了深入彻底的调查，但没有发现什么。
• He often sent them out to make investigations. 他常常派他们出去作调查。

4 helping   

n.食物的一份&adj.帮助人的，辅助的

参考例句：

• The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
• By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。

5 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

6 specimen   

n.样本，标本

参考例句：

• You'll need tweezers to hold up the specimen.你要用镊子来夹这标本。
• This specimen is richly variegated in colour.这件标本上有很多颜色。

7 specimens   

n.样品( specimen的名词复数 )；范例；（化验的）抽样；某种类型的人

参考例句：

• Astronauts have brought back specimens of rock from the moon. 宇航员从月球带回了岩石标本。
• The traveler brought back some specimens of the rocks from the mountains. 那位旅行者从山上带回了一些岩石标本。 来自《简明英汉词典》

8 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。

9 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

10 automate   

v.自动化；使自动化

参考例句：

• Many banks have begun to automate.许多银行已开始采用自动化技术。
• To automate the control process of the lathes has become very easy today.使机床的控制过程自动化现已变得很容易了。

11 automated   

a.自动化的

参考例句：

• The entire manufacturing process has been automated. 整个生产过程已自动化。
• Automated Highway System (AHS) is recently regarded as one subsystem of Intelligent Transport System (ITS). 近年来自动公路系统(Automated Highway System,AHS)，作为智能运输系统的子系统之一越来越受到重视。

12 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。

13 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

14 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

15 jack   

n.插座，千斤顶，男人；v.抬起，提醒，扛举；n.（Jake）杰克

参考例句：

• I am looking for the headphone jack.我正在找寻头戴式耳机插孔。
• He lifted the car with a jack to change the flat tyre.他用千斤顶把车顶起来换下瘪轮胎。

16 impure   

adj.不纯净的，不洁的；不道德的，下流的

参考例句：

• The air of a big city is often impure.大城市的空气往往是污浊的。
• Impure drinking water is a cause of disease.不洁的饮用水是引发疾病的一个原因。

17 undesirable   

adj.不受欢迎的，不良的，不合意的，讨厌的；n.不受欢迎的人，不良分子

参考例句：

• They are the undesirable elements among the employees.他们是雇员中的不良分子。
• Certain chemicals can induce undesirable changes in the nervous system.有些化学物质能在神经系统中引起不良变化。