What is unique about the H5N1 virus currently circulating in Asia, Africa, and Europe?
The H5N1 virus has been uniquely difficult to control in poultry flocks in affected continents. Despite the depopulation (euthanasia) of millions of domestic birds in affected countries, the virus continues to spread to other domestic birds and wild birds. In addition, the H5N1 virus spreading among birds in Asia, Africa, and Europe has caused human illness and deaths. The infection of humans with an H5 virus is rare; the influenza viruses that normally infect humans are H1 and H3 subtypes. Another unique aspect of the H5N1 (“bird flu”) virus is that it has caused deaths in wild birds. This is virtually unprecedented, and many scientific questions remain concerning the role of wild birds in the spread of the H5N1 “bird flu” virus. How have people gotten infected with the H5N1 virus? Infected birds shed large amounts of virus in their saliva, nasal secretions and feces. Human illness has resulted from direct contact with birds and their feces or with environments heavily contaminated wi