06 February, 2006
Bird Flue aka Avian Influenza aka H5N1
According to estimates by the World Health Organization, between 250,000 and 500,000 people die from normal Influenza infection each year worldwide. But the Avian Influenza has killed totally only 86 people since 2003... So what is the real risk - normal Influenza or Avian Influenza?
All the incidents are from countries like Cambodia, China, Turkey, Iraq etc. What's common with these countries is that their citizens live together with chicken and ducks and transportation of poultry is light years behind from western systems. So it should no be a big surprise why diseases spread from animals to humans so easily in those countries.
Why there's no Avian Influenza for example in Australia, India or Africa, where millions of birds migrate ever year?
Well, obviously it's not the wild birds that spread it, but it's the poultry that humans transport between countries. But it's so much easier to accuse wild birds, than start to teach poor countries how they should handle their poultry...
UPDATE 14.2.2005: First wild bird cases of avian influenza in EU
As you probably already know, 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. All the swans are believed to be Mute Swans (Cygnus 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.
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.
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.
More about this in Birdlife International's news page.