VOA慢速英语 2007 1218a
时间：2018-12-01 作者：英语课 分类：VOA慢速英语2007年（十二）月
This is the VOA Special English Agriculture Report.
Exotic Newcastle disease is a bird virus found in many parts of the world. Many kinds of birds carry it. But it especially affects chickens and a few others.
It spreads very fast and there is no treatment. Many birds die without appearing sick. The infection does not present a serious health threat to humans. But economic losses can be huge as birds are destroyed and trade is restricted to contain outbreaks.
Exotic Newcastle disease, also known as END, is the most severe form of Newcastle disease.
Experts say the easiest way to prevent the virus is to import birds from flocks that are disease-free. Vaccines 1 are also used, although experts say the virus may sometimes cause deaths even in vaccinated 2 flocks.
In the United States, the Agriculture Department says poultry 3 birds are rarely vaccinated against the virus unless an outbreak happens. The most recent outbreak began in two thousand two in California. State officials said it cost more than one hundred sixty million dollars to fight. California was declared disease-free the next year, after the killing 4 of more than three million birds.
The Global Invasive Species Database says signs of the disease may appear from two to fifteen days after a bird is infected. An infected hen lays fewer or no eggs, or eggs with thin shells. A sick bird may develop breathing and intestinal 5 problems and twist its head and neck. It may run around in circles or not move at all.
Exotic Newcastle disease spreads fastest among birds kept close together. The virus is spread through bird droppings and fluid from the nose, mouth and eyes.
To control outbreaks, experts advise quick destruction of infected flocks. They also advise limiting entry to farms and disinfecting vehicles as they come and go.
People can also transport the virus on their shoes and clothes. The virus can survive several weeks in a warm, moist environment. And there seems to be no limit if it is frozen. But ultraviolet rays in sunlight can kill it.
To reduce infection risks, the Organization for World Animal Health warns against keeping any pet birds on a farm. It even advises against hiring pet bird owners as farm workers. The Agriculture Department says Amazon parrots, for example, can spread the virus for more than a year but not get sick.
And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Steve Ember.
- 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。
- I was vaccinated against tetanus. 我接种了破伤风疫苗。
- Were you vaccinated against smallpox as a child? 你小时候打过天花疫苗吗？
- There is not much poultry in the shops. 商店里禽肉不太多。
- What do you feed the poultry on? 你们用什么饲料喂养家禽?
- 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。
- 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