What is unique about the H5N1 virus currently circulating in Asia?
The H5N1 virus has been uniquely difficult to control in Southeast Asian poultry flocks. Despite the depopulation (euthanasia) and vaccination of millions of domestic birds in affected countries, the virus continues to spread to other domestic birds. In addition, the H5N1 virus spreading among birds in Asia has caused illness in over 272 people and resulted in 166 deaths (as of Feb. 2007). The infection of humans with an H5 virus is rare; the influenza viruses that normally infect humans are H1 and H3 subtypes, specifically H1N1, H1N2, and H3N2. Another unique aspect of the H5N1 (“bird flu”) virus is that it has caused wild bird mortality. This is unprecedented, and it is not known whether these infections are from wild bird contact with infected poultry or if it is actually being transmitted by wild birds. Numerous studies are ongoing to help answer this question.
The H5N1 virus has been uniquely difficult to control in Southeast Asian poultry flocks. Despite the depopulation (euthanasia) of millions of domestic birds in affected countries, the virus continues to spread to other domestic birds. In addition, the H5N1 virus spreading among birds in Asia has caused illness among 117 people and resulted in 60 human deaths (as of October 10, 2005). The infection of humans with an H5 virus is rare; the influenza viruses that normally infect humans are H1 and H3 subtypes, specifically H1N1, H1N2, and H3N2. Another unique aspect of the H5N1 (“bird flu”) virus is that it has caused wild bird mortality. This is unprecedented, and it is not known whether these infections are from wild bird contact with infected poultry or if it is actually being transmitted by wild birds. Numerous studies are ongoing to help answer this question.
