美国有线新闻 CNN 世卫解除寨卡疫情紧急状态 中国研究对抗方法
时间：2018-12-02 作者：英语课 分类：CNN美国有线新闻2016年12月
AZUZ: It's been a while since we reported on the dangerous Zika virus, a disease carried by certain mosquitoes that are present all over the globe.
The World Health Organization, part of the United Nations, recently ended its classification of Zika as a global health emergency. But that's not because it's become less important or gone away. The organization has reclassified Zika as an ongoing threat, meaning it expects the virus to remain a problem, like yellow fever and malaria.
Most people who get Zika won't even know it. They don't have symptoms. But if a pregnant woman contracts the virus, it can cause severe birth defects or miscarriage of the baby.
In the fight against the virus, one thing researchers are looking at is trying to control mosquito populations.
In a Chinese laboratory, for example, researchers are producing millions of genetically modified mosquitoes. They're hoping these specific insects will help eliminate Zika and other diseases like dengue fever.
So, here's their plan. They start with mosquito eggs, and then infect those eggs with the bacteria that would prevent them from transmitting the viruses. Their modifications also include sterilizing male mosquitoes so that if they mate with females in the wild, the eggs won't hatch.
So, how do they separate the male mosquitoes from the females? Well, the females are larger, so they get trapped in this liquid while the males wash off. Then the males are released into the wild, 2 million a week on this Chinese island. Male mosquitoes don't bite, so researchers don't have to worry about that. And they say that this process has reduced the populations of harmful mosquitoes by 96 percent here.
Critics questioned whether this will actually eliminate mosquitoes from the area. And there are concerns about what would happen if a female mosquito somehow became genetically modified and then bit someone.
In any event, Chinese scientists are hoping to produce billions of genetically modified mosquitoes and then bring them to the Americas which have been hard hit by the virus.