What other concerns are present?
Domestic ducks excrete large quantities of the highly pathogenic H5N1 virus without showing signs of illness, acting as silent reservoirs for the virus.
The H5N1 virus circulating now is more lethal in experimentally infected mice and ferrets when compared to the H5N1 from 1997 and 2004.
The H5N1 has expanded its hosts, infecting and killing mammalian species previously resistant, for example, tigers in the Bangkok Zoo who were fed raw ill birds.
The behavior of the virus in its natural reservoir, wild waterfowl, may be becoming more lethal causing a spring 2005 die-off of migratory birds in China.