Abstract

In the past 100 years, the outbreak of avian influenza all over the world is periodic, and it is more and more frequent and harmful, which is thought to be related with deterioration of ecological environment. In recent 3 years, the outbreak of avian influenza is seasonal, it mainly breaks out from the end of fall to the beginning of winter and from end of winter to the beginning of spring, because at this time, the climate and temperature change fiercely, which is a possible inductive factor of avian influenza. By mapping the places where avian influenza broke out before 2000 and after 2003, we found that global avian influenza mainly distributed in the arc zone of West Europe, Mediterranean Sea, West Asia, Southeast Asia and Latin America, where the interaction of sea and land is intense, and fowls and water birds inhabit densely. It is demonstrated that the avian influenza virus exists in the water body like sea, lakes and swamps, and the chemicals discharged by human activities are the possible causes of avian influenza virus variation. By comparing the global space-time distribution of avian influenza with the flyway of migratory bird, we found that eights flyways are the main zones where avian influenza broke out frequently, so it can be concluded that bird migration is an important approach to spread the avian influenza all over the world.

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