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Since 2003, 58 people have died of avian flu in Southeast Asia, and unofficial reports coming out of China suggest that the number may be significantly higher. While H5N1 influenza has become endemic in Southeast Asian bird populations (the map shows the current range of the virus), deaths and infections have not, to date, spread rapidly in the human population. In nearly every reported case, humans contracted avian flu via direct exposure to infected poultry. Still, many scientists, physicians, government officials, and others, who have been watching the virus appear in a progressively larger number of countries, fear that the H5N1 virus will inevitably develop into a global pandemic.
As a result, researchers are paying close attention to H5N1's geographical spread. The disease has been found in wild and domestic birds from the Mekong area to western Russia, on the edge of the Urals and the gateway to Europe. The mechanism of the spread is unclear, however, and hotly debated. While some epidemiologists see wild aquatic fowl as the virus' private airline, a number of ornithologists feel human trade in birds is a more likely route for the virus, and that wild birds found carrying H5N1 were likely victims of chance encounters with domestic birds, and died before transporting the illness any great distance. Learn about outbreaks in affected countries, and compare the competing theories about bird migration and human trade as vectors for the spread of avian influenza with the following maps.
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