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
2010-09-25
53
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 Olsen of Umea University in Sweden. Olsen 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 Fouehier, 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 H5NI strain of bird flu?"
In poultry avian viruses can mutate(变异) into more virulent influenza strains, including H5NI. 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 H5N1. "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 often 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.
According to the author, what may be the possible carriers of bird flu?
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/C2z7777K
0
大学英语六级
相关试题推荐
A、Gradeallthehomework.B、Cleantheprofessor’soffice.C、Helptheprofessorintheclassroom.D、Sortallthedocuments.A本题的
A、Becausehewantedtomakemoremoney.B、Becausehewasfiredbytheschoolbecausehesoldpenstohisstudents.C、Becausehe
Thetaskofbeingacceptedandenrolledinauniversityorcollegebeginsearlyforsomestudents.Long【C1】______theygraduate
AcrosstheUnitedStates,scientistsaremountingwhatmaybecomethemostinnovativeagriculturalresearchdrivesincethe1920
A、Theyshouldcallthefiredepartment.B、Themanshouldgotothepartyagain.C、Themanshouldcontactthenewspaper.D、Thema
A、Becausesheissoyoung.B、Becausethemandidn’tunderstanditeither.C、Becauseshedoesn’thaveagoodknowledgeofEnglish
CharlieBellbecamechiefexecutiveofMcDonald’sinApril.Withinamonthdoctorstoldhimthathehadcolorectalcancer.After
ThepeopleoftheUSAhavebeenopposedtoacentralizedgovernmentsincelongbeforetheRevolutionof1776.Whenthe13coloni
ThepeopleoftheUSAhavebeenopposedtoacentralizedgovernmentsincelongbeforetheRevolutionof1776.Whenthe13coloni
A、ItistodeterminewhichfoodchainisthemostefficientB、Itistodescribethefoodnetworkamongplantsandanimals.C、It
随机试题
在期货行情表中,主要期货价格包括:开盘价、收盘价、最高价、最低价、集合竞价。()
求下列不定积分:
阴道自净作用与哪种激素有关( )。
女性,30岁,半年前感冒后咳嗽并伴气喘,经治疗好转,此后稍受凉或嗅到特殊气味、灰尘均有气喘发作,1日来受凉喘又发作,较剧,咳嗽,痰不多,收住院治疗为明确诊断,首选的辅助检查是
吸收剂量的单位Gy与rad的关系是
正常人心率过快致心排血量减少,则心率
()是指国家行政机关在行使行政权力、进行行政活动过程中,所遵循的法定方式、步骤和顺序。
当工程分包时,分包单位应当对( )单位负责。
进出境货物物品必须通过设立为海关的地点进境或出境。()
A.threatensB.forC.healthierA.agovernmentwithfiniteresourcesshouldsimplystoppaying【T7】_______medicalcareB.ou
最新回复
(
0
)