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39楼
发表于 2009-5-5 21:18
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据CBC NEWS:
萨斯喀彻温省(加拿大):人类和动物流感研究专家星期一试图尽量减少阿尔伯塔省的一群猪感染上猪流感,而可能更危险地使人类感染的恐惧。
通常病毒都是在一个单一的物种传染,但科学家说,猪是不同的,因为他们的肺部有接受体,使它们容易受到猪、人和家禽的流感病毒传染。
所以,阿尔伯塔省的一个农场工人能够把H1N1病毒(猪流感病毒)传递给猪,尽管这类物种之间的传染是值得关注的,渥太华大学病毒学家厄尔布朗说。
“这是因为你可能会获得更多的变体,而你不知道,变体是好还是坏, ”布朗说。 “所以,这是针对它们非常缺乏稳定性而言的。 ”
猪易于交叉感染鸟类和人类的流感病毒使它们很容易成为潜在的病毒载体,而产生新的病毒体。如果阿尔伯塔受感染的猪还感染了其他病毒,产生了新的流感病毒H1N1,加上这次季节性的普通猪流感病毒H3N2,这两种病毒的遗传物质就可能分享产生变种病毒, 这个过程被称为重组。
阿尔伯塔的猪发生这种重组的可能性非常小,萨斯喀彻温大学的约翰哈丁说,他是大型动物临床科学方面的猪健康专家。
“感染H1N1病毒的猪,同时感染其他病毒的机会,我认为是非常,非常小的。就是因为我们恰恰没有看到,今年的这个时候发生了许多猪感染了流感。”哈丁说。
猪也会有流感季节,就和人一样,而且,在猪身上这种流行性感冒病症也是很短期的。阿尔伯塔省的猪已经康复了。
如果存在两个病毒株相互抵消地合并的可能性,那就不一定会产生一个更毒株。它也未必能感染人,因为起传递作用的基因,在重组过程中,可能会失去。哈丁说。
当然,不管怎么说,人与猪都应该远离农场,如果他们有流感症状。他建议。加拿大食品检验局还应要求生产者和兽医提高其生物安全的措施,限制任何风险动物健康。
农场经营应该在监测和控制方面保持警戒,因为动物还是可能最终把一个变体细菌影响到人的健康系统,布朗说。
猪和人的流感季节在北美和欧洲行将结束,但是在南半球才刚刚开始。
SASKATCHEWAN (CBC) - Human and animal influenza experts tried to minimize fears on Monday that a herd of pigs in Alberta infected by swine flu could potentially make the infection more dangerous to humans.
Usually viruses move around within a single species, but scientists say pigs are different because their lungs have receptors that make them susceptible to swine, human and avian influenza viruses.
It's not a surprise that a farm worker in Alberta with the H1N1 virus was able to pass it along to pigs, but it is a concern when infections spread across species, said Earl Brown, a virologist at the University of Ottawa.
"It's possible that you're going to get more change and you don't know if change is good or bad," Brown said. "So it maybe speaks to a little less stability."
The pigs' susceptibility to bird and human influenza viruses make them potential mixing vessels to breed new strains. If the pigs infected in Alberta had another virus when they contracted the new H1N1 avian influenza, such as the common seasonal pig flu H3N2, the two viruses could share genetic material to produce a mutated virus a process called reassortment.
The odds of reassortment happening now in Alberta are slim, said John Harding, a swine health specialist at the University of Saskatchewan's Large Animal Clinical Sciences.
"The chances of this H1N1 virus infecting a pig at the same time it's infected with another virus I think is very, very rare simply because we just don't see that many pig influenza viruses occurring this time of year," Harding said.
There are flu seasons in pigs like in people, and influenza illness is short-lived in swine. The pigs in Alberta are already recovering.
If two viral strains defied the odds and combined, it wouldn't necessarily be a more virulent strain. It also wouldn't necessarily be able to infect people, since the genes responsible for transmission to people could be lost in the reassortment process, Harding said.
Regardless, people who work with pigs should stay away from farms if they have flu symptoms, he advised. The Canadian Food Inspection Agency has also asked producers and veterinarians to increase their biosafety measures to limit any risks to animal health.
Farming operations should be vigilant about surveillance and containment since animals could end up putting a strain on the human health system, said Brown.
As flu season for pigs and people wraps up in North America and Europe, it is just beginning in the southern hemisphere. |
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