VOA科学技术2024--Scientists Concerned about Bird Flu Among Cows

The United States plans new rules for the movement of dairy¹ cows between states because of concerns about a bird flu outbreak.

The virus is called Type A H5N1. It has been found in over 30 different groups of cows across eight states.

Some inactive markers of the virus have been found in milk sold in stores. Inactive markers mean the virus is dead and cannot harm humans who drink the milk.

The concern is that the virus could mutate, or change. It could then possibly spread from cows or other animals to humans. Experts, however, believe the risk of that is low.

After April 29, cows must have been tested and found to not have the virus before they are permitted to be moved between states.

The virus has been known by scientists to circulate² among wild birds. It appears in other animals if they eat sick birds. Some animals that live near the sea have tested positive for the virus, including harbor³ seals and polar bears. Animals that eat grasses, such as cows and goats, have only recently been found to have the virus.

Richard Webby is an influenza⁴ expert at St. Jude's Children's Research Hospital in Tennessee. He said flu viruses are known for adapting to spread among new animals. Finding⁵ the virus in dairy milk raises concerns that it could spread to people, Webby said.

Scientists confirmed the virus in cows in March after farmers said their cows were sick. They said the animals' symptoms included tiredness and low milk production. Some farmers said the milk the sick cows produced was thick and yellow.

Matthew Aliota is an animal medicine researcher at the University of Minnesota. He said finding the inactive virus in the milk "suggests this has been going on longer, and is more widespread, than we have previously⁶ recognized."

The U.S. Department of Agriculture recently sent out new genetic⁷ information about the virus.

Michael Worobey is an evolutionary⁸ biologist with the University of Arizona. He said the federal⁹ agency¹⁰ information makes him think the virus moved from birds to cows late in 2023.

Worobey said the virus likely spreads among the cows due to contact with milking machines, trucks or the shoes of farm workers. It then moves from cow to cow before making its way back to birds. Worobey said birds tested on the same farms as sick cows have a form of the virus with "clear mammalian adaptations." In other words, the virus shows signs of changing before infecting the bird populations.

Scientists say the best way to keep the virus from spreading to more cows, and possibly humans, is to test cows as often as possible and follow their movements.

Thomas Friedrich is a virology expert at the University of Wisconsin's animal medical school. "We need to be able to do greater surveillance so that we know what's going on."

Worobey said testing for active virus is one thing. But the tests must also look for antibodies, or evidence of past infections.

"That is a really accessible and quick way to find out how widespread this is," he said.

Scientists are working to be sure that heating¹¹ up the milk before it is put into containers for humans to drink is enough to kill the virus. The process is called pasteurization. The U.S. Food and Drug Administration¹² (FDA) will have more information about that soon.

Right now, the FDA recommends humans to avoid raw or unpasteurized milk. Farm workers are also being told to wear masks, wash their hands and change their work clothes often, Aliota said.

The U.S. Centers for Disease¹³ Control and Prevention said 23 people have been tested for the virus so far. One person has tested positive for a mild eye infection. CDC officials are watching for signs of sickness in 44 other people who were in contact with infected animals.

David O'Connor is a virus expert at the University of Wisconsin-Madison. He said that knowing about the virus should not make humans "change anything about how (they) live their daily lives."

But he said humans should have "increased awareness¹⁴ that something is happening."

Words in This Story

dairy -adj. cows that are raised for their ability to produce milk

marker -n. evidence of something existing

adapt -v. to change in response to external¹⁵ conditions

symptom -n. a change in the body that shows a disease is present

evolutionary -adj. describing someone who studies how something changes over time

surveillance -n. watching over something to look for changes

1 dairy   

n.牛奶场，乳品店；adj.乳制品的

参考例句：

• The yogurt sold by this dairy is delicious.这家乳品店出售的酸奶非常好喝。
• He kept a few dairy cows.他养了几头奶牛。

2 circulate   

v.（使）流通，（使）运行，（使）循环，（使）传播

参考例句：

• People who circulate false news are to be blamed.散布流言者该受遣责。
• The blood must circulate freely everywhere in the body.血液应该是全身畅通的。

3 harbor   

n.海港，港口；vt.庇护，藏匿；心怀(怨恨等)

参考例句：

• The harbor lies to the south of the city.港口在城市的南边。
• At that time,our ship was tied up at this harbor.当时我们的船停靠在这个港口。

4 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。

5 finding   

n.发现，发现物；调查的结果

参考例句：

• The finding makes some sense.该发现具有一定的意义。
• That's an encouraging finding.这是一个鼓舞人心的发现。

6 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

7 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。

8 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

9 federal   

adj.联盟的；联邦的；(美国)联邦政府的

参考例句：

• Switzerland is a federal republic.瑞士是一个联邦共和国。
• The schools are screaming for federal aid.那些学校强烈要求联邦政府的援助。

10 agency   

n.经办；代理；代理处

参考例句：

• This disease is spread through the agency of insects.这种疾病是通过昆虫媒介传播的。
• He spoke in the person of Xinhua News Agency.他代表新华社讲话。

11 heating   

n.加热，供暖，暖气装置；adj.加热的，供暖的

参考例句：

• They will install a heating and lighting system in our house.他们将在我们家装上供热供电系统。
• If the pressure is too low,the heating system will act up.如果压力太低，供暖系统就会出毛病。

12 administration   

n.经营，管理；行政，行政机关，管理部门

参考例句：

• Who is in charge of the administration of your company?你们公司的行政工作由谁负责？
• The teachers are responsible to the school administration.教师向学校行政负责。

13 disease   

n.疾病，弊端

参考例句：

• The doctors are trying to stamp out the disease.医生正在尽力消灭这种疾病。
• He fought against the disease for a long time.他同疾病做了长时间的斗争。

14 awareness   

n.意识，觉悟，懂事，明智

参考例句：

• There is a general awareness that smoking is harmful.人们普遍认识到吸烟有害健康。
• Environmental awareness has increased over the years.这些年来人们的环境意识增强了。

15 external   

adj.外部的，外面的，外来的；与外国有关的

参考例句：

• External causes become operative through internal causes.外因通过内因而起作用。
• The external features of the building are very attractive.这座建筑物的外观是很吸引人的。