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
2010-08-21
33
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 It5N1 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 H5NI 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 teat (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 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 iii 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 HSN1. "For some reason H5NI 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 HSNI.
The main sources of influenza viruses in lake water are ______, which may stay infectious for up to 30 days.
选项
答案
bird feces
解析
根据题干中的关键词lake water和30days定位到第四段,可知研究表明,湖水中的流感病毒一般是通过鸟粪传播的,这些病毒的传染性可长达30天。
转载请注明原文地址:https://kaotiyun.com/show/3x7K777K
0
大学英语六级
相关试题推荐
Let’slook【B1】______historytoanearlierwayoflife.Atonetime,childrendidn’thavetolearnanymorethanhowtocopewit
A、Recognizeanddefinetheproblem.B、Lookforinformationtomaketheproblemclearer.C、Havesuggestionsforapossiblesoluti
Directions:Forthispart,youareallowedthirtyminutestowriteacompositiononthetopic:ShouldWeReadExtensivelyorInt
Currentstudiesshowthatwhatgoesonlabelsisanimportantconsiderationformanufacturers,sincemorethanseventypercento
Afewmonthsago,millionsofpeopleinLondonheard【B1】______alloverthetown.TheEmergencyservices,theFireDepartments,
A、Herfamilyisextremelyrich.B、Herfamilyisanunhappyone.C、Theyareaccustomedtotheirlife.D、Theylongforachangein
A、Theman’swifeshouldtrytobemoreunderstanding.B、Thedepressionoftheman’swifemaybetheresultofherpastexperienc
Thejudgmentthatcigarettesmokingis【B1】______tohealthistheresultofmorethan30yearsofresearchcarriedonbyhundred
Becauseofthelimitedtimeallowances,thespeakersweretold______.(省略一切与当时正讨论的话题无关的东西)
随机试题
到货石棉板()应均匀,表面应平整光滑,不许有裂纹、孔洞和起层现象。加工好的石棉板应切直角。
下列不属于化生的是
对于DSA高压发生器的要求是
了解胎儿肺成熟度,可测定羊水的
可行性研究应具有()。
在民用机场围界外5m范围内,国家明令禁止()。
保险代理机构在开展代理业务过程中,下列情形属于不正当竞争行为的是()。
规范的公共财政理论是从( )角度推崇收取费用的。
针对评估的舞弊导致的财务报表层次重大错报风险,注册会计师应当确定的总体应对措施不包括()。错误是指非故意的财务报表错报,而故意与否往往是注册会计师难以判定的问题,需要根据具体问题进行具体的判断。对于乙注册会计师在审查B公司时发现的下列事项中,你
1949年6月30日,毛泽东发表了《论人民民主专政》一文,明确指出,历史的经验表明,资产阶级共和国的方案在中国是行不通的。最重要的经验是()
最新回复
(
0
)