H5N1 highly pathogenic avian influenza (HPAI) has so far been concentrated in Asia and is undeniably endemic in more than a few countries including China, Indonesia and Bangladesh although serious outbreaks have occurred far away in Europe and Africa. United Nations is now saying things which accumulated evidence has already indicated over the last two years: H5N1 could become endemic in parts of Europe that is if the virus has not achieved this status already.
According to FAO, the avian flu virus could become endemic in parts of Europe, with ducks and geese playing a wider role as vectors of the virus than previously thought. “It seems that a new chapter in the evolution of avian influenza may be unfolding silently in the heart of Europe,” said Joseph Domenech, chief veterinary officer of the UN’s Food and Agriculture Organization (FAO). After Asia and Africa, Europe could become the third continent where the H5N1 subtype of the influenza A virus could become endemic claimed FAO. “Europe should prepare for further waves of avian influenza outbreaks, most probably in an east-west direction, if the virus succeeds in persisting throughout the year in domestic waterfowl,” said Mr Domenech.
Concern was sparked after the loss of 365,000 ducks in southern Germany in September 2007 following detection of H5N1 antibodies in ducks which otherwise showed no signs of exposure to the virus, let alone symptoms of the disease. Virologists have long known that ducks, both domestic and wild, are able to carry the virus for long periods of time without exhibiting symptoms of disease. They are essentially ‘silent spreaders’ of H5N1, leading US virologist Dr Robert Webster to call the duck ‘The Trojan Horse’ for H5N1.
There is much circumstantial evidence to reinforce these fears. H5N1 has been continually isolated in European wild waterfowl including ducks, geese and swans since late 2005. In 2006, thirteen European Union member states confirmed cases of H5N1 - Germany, Austria, Denmark, Italy, Greece, United Kingdom, the Czech Republic, Poland, Slovakia, Slovenia, Sweden, France and Hungary - almost entirely in wild swans. Over the last few months, infected wild waterfowl have been found in France, Germany and Russia. Most outbreaks in domestic poultry have involved ducks (Germany), geese (Hungary) and the ultra-susceptible turkey (France, United Kingdom and Czech Republic). Chickens have been relatively unaffected.
Additional suspicion arose this summer when German scientists confirmed the H5N1 strain found in wild waterfowl in southern Germany had common source with that in Czech poultry. “We assume infected wild birds infected both the Czech poultry and the wild waterfowl in Germany,” said a spokesperson for the Friedrick Loeffler Institute (FLI), Germany’s national veterinary institute in on the Baltic island of Riems. She claimed it would be ‘highly unusual’ for meat exported from the Czech poultry farm to have carried the virus across the border. Analysis of the viral DNA showed a 99.2% match between the virus causing the Czech outbreak and virus in dead swans in the German city of Nuremberg. Both samples were also very similar to the H5N1 virus collected in Kuwait and sequenced in Weybridge, United Kingdom (UK).
Genetic sequencing studies conducted during the UK outbreak on the Bernard Matthews turkey farm at Holton in Suffolk (February 2007) revealed an even closer genetic match between that virus and the one that affected Hungarian geese several weeks earlier. Bernard Matthews was importing large volumes of de-boned turkey meat from Hungary on to a UK processing plant in Suffolk, located right next door to the infected turkey farm. After weeks of denial, the Hungarian authorities admitted to the UK press that in all probability the H5N1 virus entered the UK on infected Hungarian turkey meat. No H5N1 outbreaks in Hungarian turkeys have ever been reported.
Even more important to any ‘H5N1 endemic in Europe’ thesis are subsequent findings showing Hungarian goose and UK turkey strains of H5N1 were genetically very close to strains of H5N1 circulating in wild birds in Eastern Europe a whole year earlier. As we reported in July 2007, these findings in total suggest the H5N1 virus has been lodged in wild bird populations and perhaps domestic poultry in Eastern Europe since 2006. FAO veterinary experts are especially concerned about the Black Sea area where the high concentration of chickens, ducks and geese is comparable with virus-entrenched Asia, and huge numbers of migratory wild fowl stop-over and reside following migration from Northern Russia in the autumn.
