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Topic: First wild bird cases of AI in EU 禽流感首現歐盟 (Read 1287 times) |
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First wild bird cases of AI in EU 禽流感首現歐盟
« on: Feb 14th, 2006, 2:22pm » |
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BirdLife International:
First wild bird cases of avian influenza in EU
13-02-2006
http://www.birdlife.org/news/news/2006/02/avian_flu_swans.html
Three swans and a wild goose in Greece, up to 22 dead swans in southern Italy and Sicily, and a swan in Slovenia have died of avian influenza. Five of the Italian birds have tested positive for the deadly strain of the H5N1 virus that originated in poultry and has been circulating widely within Asia for the last decade. Bulgaria is expected to announce its first cases of the virus soon in infected geese.
This is another worrying development in the spread of avian influenza following the virus's appearance last week, in Nigeria. Unlike the African outbreak, however, which is restricted to poultry and was linked by the government to the illegal import of infected chickens, the European outbreaks involve wild birds.
All the swans are believed to be Mute Swans Cygus olor, a species that visits southern Italy and Greece from the Black Sea region. Their movement into southern Europe is likely to be in response to freezing weather conditions around the Black Sea.
Wild birds normally die within a few days of infection. The appearance of the swans in Italy, Slovenia and Greece indicates they were likely infected just prior to setting off on their journeys.
It is possible the swans caught the disease from other wild birds, although this is unlikely given the tens of thousands of waterfowl that have tested negative for H5N1 over the last decade. A more likely route is through contact with infected poultry or their faeces. Mute Swans, like wild geese but unlike most ducks, often feed by grazing on agricultural fields. The practice of spreading poultry manure onto fields as fertiliser is widespread in many parts of Eastern Europe, and this is a possible source of infection. The United Nations Food and Agriculture Organisation (FAO) has warned, "Viruses can stay alive in the manure for many weeks. If the manure is spread too quickly in the fields, the virus may contaminate poultry." The swan deaths highlight the need for implementation of strict biosecurity measures in infected areas, and also highlight the need for monitoring of healthy wild birds for the presence of the virus.
Swans seem particularly susceptible to avian influenza, and swan deaths have previously been reported in Russia and in October 2005 in Croatia. Tests on the Croatian swans found the birds excreted tiny amounts of the virus. Even so, it was remarkable that waterbirds sharing the same fish ponds as infected swans remained free of the disease.
The finding of dead swans will fuel the debate over how H5N1 is spreading. However, it is notable that if wild birds had been spreading the disease across continents there would have been trails of dead birds following migration routes, which isn't the case. There is still no explanation as to why certain countries on flight paths of birds from Asia remain flu-free, whilst their neighbours suffer repeated infections, nor of why only a single strain of H5N1 is found in outbreaks west of China.
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| « Last Edit: Feb 14th, 2006, 6:48pm by Webcreeper » |
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