2008年以来，禽流感病例持续增加。据联合国粮农组织高级兽医官员胡安•卢布罗特说，这明显是由候鸟迁徙造成的。
The number of cases has been rising again since 2008, apparently because of migratory bird movements, Juan Lubroth, the UN's Food and Agriculture Organization (FAO) chief veterinary officer, said.
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