While the world's attentions have been focused on dealing with the H1N1 pandemic, avian influenza H5N1 has quietly continued to take its toll on both poultry and humans.

Last year, 17 countries, including Côte d’Ivoire, Germany, China and Japan, reported outbreaks of H5N1 in domestic poultry and wild birds. WHO, which still says H5N1 poses a pandemic threat, documented 72 human cases, 32 of them fatal.The brunt of the outbreak, now entering its eighth year, is still in China and the developing countries of Southeast Asia. Indonesia boasts the greatest death toll last year –19 of the 32 H5N1 deaths; China recorded 5 deaths and Vietnam had 4.   The number of human deaths has been dropping since peaking at 79 in 2006. And fewer countries reported outbreaks in 2009 than in 2008.

Backyard Culling
At a recent meeting in Southeast Asia, scientists reported that carefully targeted culling can be just as effective as widespread culling, and less disruptive.

Others reported that reducing risk among those keeping backyard poultry has to be a community-wide effort, since changing the practices of individual farmers has proven difficult. There is also a 3-year-old regional surveillance network that is making progress in sorting out the role of wild birds. Some waterfowl initially thought to be spreading the virus, such as the Asian openbill stork, are now known to quickly succumb to H5N1 infection. But passerine species, or perching birds, are apparently carrying the virus without ill effects. He adds that there is a high correlation of outbreaks in poultry and passerine movements.

It remains unclear what is sustaining the outbreak, whether there is a natural reservoir for H5N1, and how the virus is passed between domestic and wild birds. But while that research continues, the most effective way to reduce the amount of virus in circulation is to control outbreaks in poultry, he says.

For a complete record of the H5N1 avian influenza virus outbreak from 2003 up to the present go to the WHO table of confirmed human cases of avian influenza A/(H1N1) as of 30 Dec 2009 at and the WHO timeline at

From December 2003 – December 2009 there have been 467 confirmed human cases and 282 deaths. Of the 5 countries reporting H5N1 cases in 2009 mortality was least in Egypt with 4 deaths among 39 cases and highest in Indonesia with 19 deaths among 20 cases, suggesting that surveillance and treatment procedures may be improving.

Science insider

ProMED Digest V2010 #26