首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Wild ducks and other migratory (迁移的) birds could be important carriers of deadly bird flu, researchers say. Even so, the infecti
Wild ducks and other migratory (迁移的) birds could be important carriers of deadly bird flu, researchers say. Even so, the infecti
admin
2009-08-19
76
问题
Wild ducks and other migratory (迁移的) birds could be important carriers of deadly bird flu, researchers say. Even so, the infectious-disease experts say there is no solid basis for killing wild birds to protect poultry and minimize the risk of human infection.
The European team investigating the global spread of the H5N1 strain of avian influenza (禽流感) says certain duck species may be infecting wild bird populations. Geese and wading birds are also possible vectors (带菌者) of the virus, the team says.
The team’s study was led by Bjorn Olseo of Umea University in Sweden. Olsan runs Europe’s largest wild-bird flu monitoring program.
Studies have shown that influenza viruses in lake water, generally passed via bird feces(粪), can stay infectious for up to 30 days. The migration or feeding behavior of dabbling ducks could at least partially explain the spread of the H5N1 strain of bird flu, the researchers add.
This group of duck species includes mallards, teal, pintails, and others that feed at or near the surface, where viruses in water are most likely to be picked up. Perhaps as a result, dabblers have the highest known rates of avian influenza infection, the study says. For instance, nearly 13 percent of mallards tested positive for bird flu. Other species tested include the American black duck (18.1 percent), blue-winged teal (11.5 percent ), and northern pintail (11.2 percent).
However, bird flu viruses appear to exist in ducks in a low-pathogenic form, meaning infection doesn’t usually lead to severe illness and death.
"Dabbling ducks are for sure the prime hosts for low pathogenic viruses," said study co-author Ron Fouchier, a virologist at the Erasmus Medical Center in Rotterdam, Netherlands. "But the big question is, how much of our knowledge about these viruses can we translate to high-pathogenic viruses such as the H5N1 strain of bird flu?"
In poultry avian viruses can mutate(变异) into more virulent influenza strains, including H5N1. If this mutated virus then finds its way back into wild populations, the birds could then spread the disease through migration.
Some scientists have argued that wild birds infected with HN51 would be too ill to migrate. Swans, for instance, appear to be particularly vulnerable to the strain. "Swans apparently drop dead quite easily, but they are unlikely to be the vector because they are not going to fly very far if they are dead," Fouchier said.
But the study team says that some birds that have been purposely infected for the sake of research show that wild birds can survive H5NI. "For some reason H5N1 has adapted so it no longer kills dabbling ducks," Fouchier said. This means the ducks may be able to spread the virus over a wide area.
The study team says migratory geese may also be vectors, because they olden graze in huge flocks, a practice that could encourage transmission.
Migrating ducks, the researchers add, "could provide an intercontinental bridge" for bird flu to North America, which has not yet had any known cases of H5N1.
选项
答案
Wild ducks and other migratory birds. /Ducks,geese and wading birds.
解析
文章开头指出,野鸭以及其他迁徙鸟类可能是致命性禽流感的重要携带者,由此可得答案;第二段又提到,鸭子可能在传染野鸟,而鹅和涉水鸟也可能是病毒的携带者,由此也可得答案。
转载请注明原文地址:https://kaotiyun.com/show/BodK777K
0
大学英语六级
相关试题推荐
Howmuchshouldyouincludeonaresume?Bothexperiencedcandidatesandrecentgraduateswithlimitedexperienceaskthisquest
Afterfinishinghishomeworkhewenton______(write)alettertohisparents.
Imaginethis:yourparentsgoawayonbusiness,butyouhavetostayathomealone.Wouldlifebeaseasyaswhenyourparentsare
Beforehisdeathlastyear,ProfessorJohnsondecidedthathe________leave$2,000,000tohisuniversity.27.Inthemuseum,we
Dotheresultsoftheresearchhaveanypractical(apply)________?
Pollutionhasbecomeaseriousprobleminalmostallthebigcitiesoftheworld.Citypeoplearebecomingmoreandmoreworried
Pollutionhasbecomeaseriousprobleminalmostallthebigcitiesoftheworld.Citypeoplearebecomingmoreandmoreworried
Howdopeopleoftenmeasureprogressinagriculture?Specialisationandtheefforttoincreaseyieldshaveresultedin______.
A、Acaketin.B、Amicrowaveoven.C、Arollingpin.D、Flour.BWhichofthefollowingisnotmentionedbyDoristomakeacakewit
随机试题
无症状肾癌多发现于
A.以老年男性多见,常为中央型肺癌,生长速度较慢,对放疗和化疗较敏感,血行转移发生较晚B.多起源于大支气管,细胞大,胞浆丰富,胞核形态多样,分化程度低,常在发生脑转移之后才被发现C.多发于年轻男性,常为中央型肺癌、恶性程度高,生长快,较早出现淋巴和血行
用溶栓药治疗肺血栓栓塞症后,规范性肝素治疗应开始于凝血酶原时间恢复到正常值的
高钾血症是指血清钾高于
1972年,戴维斯对CBD中的零售业布局提出了一个结构模式,认为以零售业为主的区位用地选择除了受空间距离的影响外,还受三个相互独立的交通通达性的影响,其中城市中心区传统性的购物活动、其他商务(如汽车修理厂、咖啡馆等)、一些特殊性功能(如娱乐设施、家具展销店
县级以上地方人民政府有关部门为就业困难人员安排的给予岗位补贴和社会保险补贴的公益性岗位,其劳动合同不适用劳动合同法有关()的规定。
国家应保护个体经济的合法权益,对个体经济实行()。
将10个相同的小球放入编号分别是1、2、3的盒子里,若每个盒子里球的个数不小于它的编号,则共有多少种方法?
OnlineTherapyIsn’tShrinkingOnlinetherapyisdangerous,criticssay.Quackscouldsetupshopandcheatcustomers.Disco
TheAlzheimer’sAssociationandtheNationalAllianceforCaregivingestimatethatmenmakeupnearly40percentoffamilycare
最新回复
(
0
)